VIETNAM PETRO Petro ietnam An Official Publication of The Vietnam National Oil and Gas Group Vol - 2011 ISSN-0866-854X Biofacies and sequence stratigraphy, Oligocene to Pliocene, Cuu Long and Nam Con Son Basins, Vietnam Te Giac Trang field: Geological features, reservoirs and field development concepts PETROVIETNAM JOURNAL IS PUBLISHED MONTHLY BY VIETNAM NATIONAL OIL AND GAS GROUP Editor-in-chief Dr.Sc Phung Dinh Thuc Deputy Editor-in-chief Dr Nguyen Van Minh Dr Phan Ngoc Trung Dr Vu Van Vien Editorial Board Members Dr Sc Lam Quang Chien Dr Hoang Ngoc Dang Dr Nguyen Minh Dao PETROVIETNAM Petro ietnam BSc Vu Khanh Dong Dr Nguyen Anh Duc MSc Tran Hung Hien MSc Dao Duy Khu Dr Vu Thi Bich Ngoc MSc Le Ngoc Son MSc Nguyen Van Tuan Dr Le Xuan Ve Dr Phan Tien Vien Dr Nguyen Tien Vinh Dr Nguyen Hoang Yen Secretary MSc Le Van Khoa BSc Vu Van Huan Contact Address 16 Floor, VPI Tower, Trung Kinh Street, Yen Hoa Ward, Cau Giay District, Ha Noi Tel: 84.04.37727108 Fax: 84.04.37727107 Email: tapchidk@vpi.pvn.vn Mobile: 0982288671 Designed by Le Hong Van Publishing Licences No 170/GP - BVHTT dated 24/04/2001; No 20/GP - SĐBS 01, dated 01/07/2008 Contents PETROLEUM EXPLORATION & PRODUCTION 24 31 The characteristics of Miocene sedimentary rocks in the Western Cuu Long Basin 49 CO2 management at Exxonmobil's labarge field, Wyoming, USA 60 A Sector Compositional Model for Hydrocarbon Gas Injection Study 67 Agricultural residues - generation feedstock for ethanol production in Vietnam 74 NEWS Advanced drilling in HPHT: The TOTAL experience on Elgin Franklin (North Sea - UK) 38 PETROLEUM PROCESSING Te Giac Trang field: Geological features, reservoirs and field development concepts Development of a Kinetic Model for the Aromatisation of Propane and Propene over H-ZSM-5 Catalyst under Deactivating Conditions 79 PVEP concludes a $200 million term loan facility with Vietinbank 80 PVFCCo launches a new fertilizer brand - Phu My NPK nd PETROVIETNAM Biofacies and sequence stratigraphy, Oligocene to Pliocene, Cuu Long and Nam Con Son Basins, Vietnam Jim Cole Tie-Point Geoscience Abstract Detailed biostratigraphical studies on wells from the Cuu Long and Nam Con Son Basins reveal five genetic 2nd order megacyclical tectonostratigraphical sequences bounded by regional flooding surfaces, dated as Late Oligocene, Early Miocene, Middle - earliest Late Miocene, Late Miocene and Plio-Pleistocene respectively The section in both basins is non-marine to marginal marine over the Oligocene to Middle Miocene, where palynology is the only viable microfossil group for age dating, though there are actually few good strict palynostratigraphical markers However stratigraphical resolution is considerably enhanced by the recognition of progressive and recurrent palynofacies to mark biofacies zones An attempt has been made at relating these zones to transgressive, highstand and lowstand system tracts, making use of the known palaeoenvironmental limits of certain palynomorph taxa whose analogues occur in modern environments In this way twenty-five regionally correlatable, possibly sea-level controlled, 3rd order cycles have been recognised within the five 2nd order cycles This scheme is in its infancy and is open to refinement as more wells are studied, but is currently complete enough for application to any new well drilled in either basin It has already led to some radically revised age assignments amongst legacy wells so far studied In addition, there are some important differences in sedimentary regime between the Cuu Long and Nam Con Son Basins, reflected in the palynofacies assemblages, particularly within the Late Oligocene and Early Miocene Age constraining of sedimentary units is particularly important in petroleum exploration of the Vietnam offshore The section has a plethora of repetitive clastic lithologies The characteristics of some of these intervals as potential migration zones or stratigraphical traps (as detectable from fluid inclusion studies), need to be accurately delineated within a workable regional sequence stratigraphical scheme Introduction The Cuu Long Basin lies just ofshore from the Eastern Sea coast of Southern Vietnam It is separated to the South by a basement high, the Con Son Swell, from a larger region of several sub-basins comprising the Nam Con Son Basin that straddles a large part of Vietnam’s territorial waters and partially overlaps into other basins in Malaysian and Indonesian waters (Fig 1) Basin initiation has been related to phases of extension associated with the collision of India and Asia causing ‘extrusion’ in SE Asia along major lineaments, (Tapponier, et al 1982) Movements in the Middle Miocene caused brief compression and basin inversion with a regionally recognised Middle Miocene unconformity The sedimentary sequence of the Cuu Long and Nam Con Son Basins largely comprise heterogeneous but PETROVIETNAM - JOURNAL VOL 6/2011 PETROLEUM EXPLORATION & PRODUCTION Though most are long ranging, palynomorphs are present in large numbers within most cuttings samples available from the Late Palaeogene - Early Neogene Many of them have analogues in the present day across a range of depositional settings making them valuable palaeoenvironmental markers This permits known palaeoecological controls to be taken back into the Tertiary in depositional environment analysis Fluctuations in the abundance and relative frequency of eco-speciic palynomorphs over a stratigraphical section are therefore a proxy of environmental change and position with respect to the global sea-level cycle Palynofacies and microfacies analysis (Fig 4) reveals a progressive overall trend of increasing and deepening marine inluence throughout the Tertiary in both the Cuu Long and Nam Con Son Basins For this reason sea-level change must be a prime underlying mechanism in sedimentation Morley (1991) has indicated that two of the principle controls on vegetation distribution are orogeny and climate, factors themselves that are part under the control of sea-level change Sequence stratigraphy provides a way of “… subdividing basin-ill into a series of time and spatially related units, which ofer a dynamic representation of lateral facies relationships Fig Cuu Long Basin - Con Son Swell - Nam Con Son Basin, Vietnam by tracing the evolution of depositional systems in response to transgressions and regresmonotonously alternating sandstones and mudstones sions forced by cycles of relative sea level change” that are diicult to constrain and correlate lithostrati(Courel et al 2008) graphically and by wireline logs Major limestone units are This paper investigates the opportunity of using present in the Nam Con Son Basin (Fig 2) biofacies trends at a more reined level in sequence Additional diiculties arise from the presence of few stratigraphical analysis Identiication of similar biofaage restricted microfossils for strict biostratigraphical age cies trends across a number of intra-basin wells should determination Much of the interval of exploration interest provide several additional correlation tie-points If such (Oligocene - Middle Miocene) is non-marine or marginal trends can be demonstrated to be sea-level controlled, marine, yielding only long ranging palynomorphs (Fig 3), their value as time synchronous cross-facies stratal surthough more open marine sections in the later Neogene faces can be validated In this way a number of suppleyield good micropalaeontological and calcareous nannomentary time-lines become available to add to the FAD’s fossil age markers Marine inluence commenced earlier and LAD’s (irst and last occurrence datums) from age and is more strongly evident in the biofacies of the Nam diagnostic biostratigraphical taxa alone A sea-level drivCon Son than the Cuu Long Basin PETROVIETNAM - JOURNAL VOL 6/2011 PETROVIETNAM en sequence stratigraphical model may also provide a means of inter-basin correlation between the Cuu Long and Nam Con Son Basins Morley (1991) used quantitative palynomorph zones in improved stratigraphical resolution in the SE Asian Tertiary and mentioned the elimination of non-stratigraphical quantitative events whose correlation lines cut across good biostratigraphical correlation datums A recommendation of a well minimum database for initiation of a quantitative local scheme within a basin was mentioned with a further wells, a total of therefore, suggested as the requirement for full elaboration and assembly of a scheme erected on a series of quantitative events for basin-wide predictive purposes Megasequences Five megasequences based on gross palynofacies characteristics have been recognised within the Tertiary sequence of ofshore Vietnam These have been given the suix V and are numbered stratigraphically, V0 - Late Oligocene; V1 - Early Miocene; V2 - Middle Miocene to earliest Late Miocene; V3 - Late Miocene and V4 - Plio-Pleistocene, (Fig 2) These megasequences encapsulate Geological Stages based on the Geologic Time Scale of Gradstein et al (2004), as revised from Haq et al (1988) and Hardenbol et al (1998) They are mostly placed at Sequence Boundaries (SB) in sequence stratigraphy parlance at the shift from highstand systems tract (HST) to lowstand systems tract (LST) These are dated at: 23.03 Ma - top Oligocene (Chattanian, Ch4/Aq1) 16.97 Ma - top Early Miocene (Aquitanian/Burdigalian, Bur5/ Lan 1) 11.61 Ma – top Middle Miocene (Langhian/Serravallian, Ser4/ Tor1) 5.33 Ma – top Late Miocene (Tortonian/Messinian) 0.05 Ma – top Plio-Pleistocene (Zanclean/Piacensian/Gelasian/ Pleistocene) Fig Sequence Stratigraphy Scheme, Cuu Long and Nam Con Son Basins Each of the megasequences V1 - V4 are marked at their base inception by a major increase in marine microfossils The actual biofacies boundary may then, be better deined using the scheme of Galloway (1989) that places PETROVIETNAM - JOURNAL VOL 6/2011 PETROLEUM EXPLORATION & PRODUCTION based on microfaunal and nannoplankton evidence The biozones of these marine microfossils are N16 and NN9 respectively (early Late Miocene) that are recognised to be present in the upper part of V2 megasequence Microfaunal and nannoloral evidence is not available at earlier stages than the Late Miocene due to the paucity of marine facies in the Vietnam basins A convenient major looding surface, post N16 for the V2 - V3 boundary occurs at 8.0Ma within the Tortonian Stage Megasequence V3 encapsulates the remainder of the Late Miocene, nannofossil zones NN10-NN11, (Late Tortonian - Messinian) with its upper boundary, as mentioned at a looding surface rather than sequence boundary, at 5.33Ma on the global scheme Megasequence V4 encompasses the Pliocene and Pleistocene Biofacies in sequence recognition This section examines some of the eco-speciic palynomorphs and palynofacies of the Vietnam Tertiary section and the way they might be expected to respond in within transgressive, highstand and lowstand systems tracts 3.1 Transgressive system tract (TST) Fig Palynofloral Zones, Cuu Long and Nam Con Son Basins sequence boundaries at looding surfaces This occurs slightly younger in the section, with the exception of the Miocene - Pliocene boundary (V3-V4) at 5.33 Ma that is already placed at a looding surface on the Geological Time Scale of Gradstein et al (2004) Megasequence boundaries at the initial transgressive surface of the next transgressive systems tract (TST) or maximum looding surface at the base of the ensuing high stand systems tract (HST), as used in this study are as follows: 22.3 Ma - Late Oligocene, V0 15.8 Ma - Early Miocene, V1 8.0 Ma - Middle Miocene - early Late Miocene, V2 5.33 Ma - Late Miocene, V3 0.05 Ma - Plio-Pleistocene, V4 Megasequence V2 is dated as Middle Miocene to early Late Miocene (Langhian, Serravallian and Early Tortonian) Age of the upper boundary of this megasequence is PETROVIETNAM - JOURNAL VOL 6/2011 Following lowstand sedimentation an initial looding surface marks commencement of deposition of the transgressive systems tract, with back-stepping retrogradational iner grained shelfal sediments Ravinement erosion of the underlying sediments may occur with the pene-contemporaneous reworking, making the boundary appear less clear cut in terms of its biofacies Rapid creation of accommodation space leads to a distinctive shallow marine microfauna if underlying open marine ingress into the basin is near and strong enough Mangrove pollen with marine dinocysts and other marine palynomorphs such as chitinous microforaminiferal linings may rapidly become an increasingly important component of each successive parasequence up through the sequence In more high angle beach settings, pollen of plants such as Casuarina, Marginipollis concinnus, Pandaniidites sp and Echiperiporites estelae are particularly evident If the basin remains in an interior continental setting or is distal with respect to the direction of marine ingress, raised base level will be manifest by an increase in lacustrine algae and pteridophyte spores of associated waterlogged terrain, such as Magnastriatites howardi PETROVIETNAM looding surfaces within the early phase of high stand sedimentation are suiciently open marine in the later phase of 2nd order thermal sag, they will yield correlatable microloral and microfaunal assemblages 3.3 Lowstand systems tract (LST) During falling stage sediment accommodation space is at a premium This efectively reduces the area available for deltaic and coastal plain sedimentation, leading to a reduction in mangrove and lowland freshwater pollen representation in the palynomorph assemblages Withdrawal of the sea from the shelf leads to incision as clastic detritus is conveyed to the slope and basin of the shelf edge Carbonate sedimentation on the shelf edge may be promoted Sediment by-pass of the shelf and upper slope may lead to non-sequences and higher Fig Microfacies Scheme, Cuu Long and Nam Con Son Basins energy of low as the ‘nick’ point erodes back over an increased al3.2 Highstand systems tract (HST) luvial gradient If sea-level does not fall below the existFollowing the R-inlection point of maximum rate of ing shelf sediments of the earlier highstand, then a shelf sea-level rise, with the maximum looding surface, sedimargin wedge systems tract may be produced mentation may continue over an area of plentiful accomWith either shelf margin wedge sedimentation or modation space, but it can become more regressive, proshelf incision, coarser clastic lithologies tend to predomigradational in aspect Palynoloral assemblages will be nate with the higher energy run-of alluvial low rates dominated by lowland freshwater pollen types and where The winnowing efect of the current leads to dispersal waterlogging persists in a non-marine setting, pteridoand destruction of organic material Palynomorph asphyte spores, including Magnastriatites howardi from the semblages tend to be quite poor, coinciding with coarser aquatic fern Ceratopteris clastic lithologies Where palynomorphs are present they Restricted basins or those distal to the open marine are dominated by a lower diversity of taxa and a greater realm may register continued high freshwater base level concentration of montane gymnosperm pollen such as from the earlier TST phase, recording raised lacustrine alPiceapollenites sp., Pinuspollenites sp Alnipollenites sp and gae in the biofacies as alluvial run-of tends to be trapped Zonalasporites sp and ponded within the basin Lowstand sedimentation coincides with glacial maxiThis is indicative of the highstand systems tract If ma, which in the tropics may lead to increased seasonality PETROVIETNAM - JOURNAL VOL 6/2011 PETROLEUM EXPLORATION & PRODUCTION with a more marked dry season Lowland everwet rainforest pollen types may be reduced in favour of shrub loras dominated by fern spores and savanna grassland with Monoporites annulatus Biofacies of megasequences In this section broad trends of environmentally signiicant taxa from a number of wells are examined in terms of their value as sea-level indicators for both basins This has permitted compilation of summary palynoloral biofacies (palynofacies) for the Cuu Long Basin, (Fig 5) and for the Nam Con Son Basin, (Fig 6) These diagrams provide a general summary of correlatable ‘bioevents’ for these two basins… 4.1 V0 Megasequence (Fig 7) Sediments of the Palaeogene, rift-ill V0 megasequence, Tra Tan Formation of the Cuu Long Basin are typically characterised by the Oligocene marker taxon Ver- rutricolporites pachydermus (an early morphotype within the Florschuetzia trilobata complex) with abundant freshwater algae Bosedinia sp., Pediastrum spp and Botryococcus spp., with a very distinctive lufy brown sapropelic organic matter (SOM) The latter is highly organic and hydrogen rich, typical of deposition in meromictic (stratiied) water bodies of lacustrine character Rare marine palynomorphs and marine microfauna occur, but they are probably caved This is a well known and a primary regional source rock of numerous back-arc, Pannonian and continental rift fracture basins around the periphery of the Sunda microplate of the Eastern Sea, Malaysia and Western Indonesia, (Cole & Crittenden, 1997) In the Nam Con Son Basin, studies to date have revealed very little of the Cau Formation section Samples that have been examined yield poor palynomorph recovery with V pachydermus and other freshwater pollen plus records of the lacustrine alga Pediastrum Samples yield common inertinitic kerogen derived from coal seams indicative of freshwater swamp deposition 4.1.1 Sequences The V0 sequence in the Cuu Long Basin reveals some marked downhole changes in abundance of the lacustrine algae Botryococcus, Bosedinia and Pediastrum in a few wells that have penetrated a good interval of the Late Oligocene There are also changes in the kerogen type It is uncertain that these changes can be related to sea-level efects within these continental rift basins Morley (1991) has noted that mangrove taxa of the Florschuetzia group and the back mangrove taxon Discoidites borneensis may have had a freshwater swamp origin in the Palaeogene Fig Palynofacies Defined Genetic Sequences, Cuu Long Basin, Vietnam PETROVIETNAM - JOURNAL VOL 6/2011 Sequences V0a, V0b and V0c have been tentatively recognised PETROVIETNAM pending further studies, but they may be more related to local changes in water conditions, though base level effects within non-marine settings are known, (Cole & Crittenden 1997; Cole et al 2005) Very little of this sequence has been seen in the Nam Con Son Basin, but its depositional facies is diferent from the Cuu Long Basin Lacustrine facies are present representing small ephemeral ponds and lagoons associated with peatswamps, not the deep stratiied semipermanent lakes of the Cuu Long Basin 4.2 V1 Megasequence (Fig 8) Early Miocene sediments are distinguished palynologically by the occurrence of Florschuetzia semilobata and F trilobata below the evolutionary appearance of F meridionalis The Bach Ho Formation of the Cuulong Basin records the irst occurrence of in situ marine microfossils This marine indication is only slight, in the form of rare dinocysts, chitinous foraminiferal linings in the palynomorph assemblage, plus locally common occurrences of the brackish marsh agglutinating foraminifera Jadammina cf macrescens and the gastropod Littorina spp in the microfaunal analysis There is an absence of open marine planktonic foraminifera and calcareous nannofossils In the palynomorph assemblage freshwater lacustrine algae remain very prominent, particularly Botryococcus spp and Pediastrum spp., but reduced occurrences of Bosedinia spp There is a diversity of freshwater pollen and spore taxa, particularly Magnastriatites howardi Kerogen assemblages yield common amorphous kerogen (AOM) though not the SOM rich component seen in the V0 megasequence Nonethe-less these lacustrine phases provide an important subsidiary source rock facies, though to a lesser degree than in the syn-rift section Fig Palynofacies Defined Genetic Sequences, Nam Con Son Basin, Vietnam Dua Formation assemblages from the Nam Con Son Basin yield an abundance of the lacustrine alga Pediastrum spp, but not records of Botryococcus spp, or Bosedinia sp., indicative of smaller, less permanent, ephemeral lakes that may have been subject to minor marine inundation Pteridophyte spores and gymnosperm pollen are comparatively common Marine palynomorphs are present in increasing numbers up through the megasequence and the microfaunal analysis reveals J cf macrescens plus Elphidium cf tikutoensis and rare ostracods PETROVIETNAM - JOURNAL VOL 6/2011 PETROLEUM PROCESSING structure The mechanism of steam explosion makes it extremely impact on lignin The decrease of lignin content plays an important role in the destruction of structural feedstock helping enzyme to attack cellulose easily in the next hydrolysis step 2.3 Enzymatic hydrolysis (saccharification) Fig Sugar concentration in pretreated solution Experimental results in the pretreatment step showed that: + Sulfuric acid method: The corncob feedstock gives highest sugar concentration, the next is bagasse and the lowest is rice straw It is shown that the lignocellulosic structure of bagasse is relatively stable, followed by that of rice straw while corncob‘s structure is less stable than the others Therefore, sulfuric acid pretreatment may be effective with corncob and bagasse; After the pretreatment step, the pretreated residues were hydrolyzed Several experiments were perfomed to choose the optimal conditions of the hydrolysis step using Vicozyme L and micro organism Biovina Main parameters investigated this step are as follows: + Pretreatment method + Enzyme weight percentage + Subtrate concentration + Hydrolysis time Table summarizes optimal conditions of the hydrolysis step for different feedstocks obtained from experimental results The obtained results of hydrolyzing pretreated residues with above optimal conditions are shown in Table + Steam explosion pretreatment is suitable for rice straw since the sugar concentration in pretreated solution is slightly higher than Table Optimal conditions in enzymatic hydrolysis ste that obtained by sulfuric acid method using the same feedstocks This is rationalized by the fact that rice straw has high lignin content while lignin destruction in the pretreatment step also affects the destruction of the hemicellulose and cellulose in lignocellulosic Table The experimental results of hydrolysis step 70 PETROVIETNAM - JOURNAL VOL 6/2011 PETROVIETNAM The experimental results (in Table 4) indicate that: Table The experimental results of fermentation step + Hydrolysis yield of biomass feedstocks is very low because of the space effect of their structure Although the materials were pretreated, structure of some species around cellulose still remain, like hemicelluloses and lignin, substances which are formed in pretreatment In addition, cellulose itself also has a complex structure There are many chemical bonds among cellulose molecules and its monomer (6 carbon sugar) The enzymes which were conducted in this study are not suitable with cellulosic materials; the enzymes for converting cellulose to sugar have not yet been commercialized, therefore, the result of the hydrolysis stage is eventually low When Biovina micro organism is used, the sugar concentration obtained from hydrolysis is much lower than that of Viscozyme L since Biovina has not been purified, contaminants removed and cellulase activity of the enzyme improved; + Pretreatment plays an important role in the ethanol production process using biomass feedstock because this step helps to increase the hydrolysis ability of feedstocks 2.4 Fermentation Products of the hydrolysis step and pretreating liquid were blended at a 1:1 ratio before fermentation The optimal conditions of the fermentation step were determined as follows: The fermentation results are shown in Table Analytical result of fermentation solution indicated that there are also other compounds apart from ethanol such as organic acids, methanol and acetone, but their quantity is negligible (Table 6) Table Composition of fermentation solution IV Discussion The results of this study indicate that three main chemical components of biomass are cellulose, hemicellulose and lignin The cellulose and hemicellulose content in corncobs and bagasse is high (cellulose: 42 44%, hemicelluloses: 21 - 30%), which is an advantage for the production of ethanol This content present in rice straw is low (36% cellulose, 24% hemicellulose) The lignin content in bagasse and rice straw (18 - 21%) is higher than that of corncobs (15%) Therefore, it is difficult to break down the bagasse and rice straw structure and hydrolyze cellulose into sugar For the pretreatment step, the use of dilute sulfuric acid of 1% wt at 1080C within hours is suitable for corncob and bagasse whereas steam explosion method at 2100C is suitable for rice straw Pretreatment plays an important role for converting biomass into ethanol since this process improves the cellulose hydrolysis efficiency to produce sugar, which greatly influences the conversion of agricultural residues to ethanol as well as the ethanol production cost For the hydrolysis step, hydrolysis yield is very low (< 50%) because the cellulosic structure of agricultural residues is very stable and complex For the fermentation step, ethanol concentration is very low (about 2% vol), the quantities of by-products PETROVIETNAM - JOURNAL VOL 6/2011 71 PETROLEUM PROCESSING such as methanol, acetone, acetic acid are much lower than those stipulated in the TCVN 7716:2007 standard for denatured ethanol fuel The low concentration of ethanol will strongly influence the production cost of the next steps (distillation and purification) The experimental results indicated that: Three factors affecting the ethanol production process (from agricultural residues) are feedstock, product and technology - Feedstock: Agricultural residue resources are available and meet the demand for ethanol production in Vietnam - Product: Ethanol from agricultural residues meets the TCVN 7716:2007 standard for the denatured fuel ethanol - Technology: Enzymes and yeast used in this study are not suitable due to low efficiency and need to be improved in order to increase ethanol yield and to reduce production cost The low efficiency makes ethanol production cost from biomass very high compared to those of gasoline and ethanol produced from the first generation feedstock (cassava, sugarcane,) As a result, technology has not commercialized up to now In the whole ethanol production process, pretreatment and hydrolysis are two important steps, which affect the current production cost: + Pretreatment: This step is necessary to break down the lignocellulosic structure and to increase the hydrolysis ability of cellulose With the applied methods, the main improvements are to combine processes, to optimize conditions and to reduce heat loss On the other hand, the biological pretreatment method should also be studied since this process is implemented in mild conditions and require less facility, which eventually could reduce the production cost + Hydrolysis: This is the process converting cellulose into sugars The cellulosic structure of agricultural residues is much more complex than that of the irst generation feedstock (sugar cane, starch ) Therefore, it requires speciic enzymes or micro organisms for agricultural residue conversion Currently, enzyme has not been commercialized yet Besides, reducing the hydrolysis time should be considered to lower the production cost 72 PETROVIETNAM - JOURNAL VOL 6/2011 In short, if the technological issues are solved, the production of ethanol from biomass feedstock (agricultural residues) in Vietnam will be promising V Conclusions and suggestions This is an initial study about agricultural residues as well as ethanol production technology from biomass feedstock in Vietnam The survey results showed that agricultural residues in Vietnam are abundant, which could be potential feedstocks for ethanol production The experimental results indicated that conversion yield of agricultural residues into ethanol is still low because technology, enzymes and yeast have not been commercialized yet As a result, the cost of ethanol production from 2nd generation feedstock is still very high For reducing the production cost, the authors suggest that several studies on ethanol production from biomass in Vietnam should be further pursued as follows: - Biochemical technology: + Pretreatment step: improve existing pretreatment methods and investigate the biological pretreatment method Consider the technical aspects to integrate the pretreatment process with the current ethanol production plant of Petrovietnam; + Hydrolysis step: Continue to collaborate with worldwide partners to obtain commercial enzyme for a larger scale study On the other hand, collaborate with a local partner to prepare micro organisms domestically; + Investigate Consolidated bioprocessing (CBP), which integrates the enzyme production, hydrolysis and fermentation into a single system to reduce the investment cost + After improvement of processes, it is necessary to conduct at a larger scale (pilot) project to fully assess the economic efficiency through the optimization of process, utilities, chemicals and utilization of by-products - Thermo-chemical technologies: in parallel with above studies, conduct study on liquid production (ethanol, biodiesel, chemicals, fuel) from agricultural residues through fast pyrolysis process combined with hydrodeoxygenation (HDO) or Fisher Tropsch pathway (biorefinery) PVJ PETROVIETNAM References Author Group of SriConsulting PEP Yearbook China s.l. : SriConsulting, 2008 pp 361-366 Hettenhaus, J., 2006 Achieving Sustainable Production of Agricultural Biomass for Biorefinery Feedstock Washington DC: Biotechnology Industry Organization B.C Saha, L.B Iten, M.A , 2005 Cotta and Y Victor Wu, Dilute Acid Pretreatment, Enzymatic sachariication and Fermentation of Rice Husk to Ethanol http://www.rauhoaquavietnam.vn/default.aspx?t abID=5&ID=20&LangID=1&NewsID=662&PageNum=19 Viet Nam fruits vegetables [Online] 11, 2007 Authors of Sacombank stock company Lam Son Joint stock company - Exceeding the year plan in the first month of year s.l. : Sacombank stock company, 07/2009 Food technology faculty Essay about handling molasses and application of products after treatment in life s.l. : Ha Noi University of Agriculture 1, Ha Noi, 2008 PETROVIETNAM - JOURNAL VOL 6/2011 73 PETROLEUM PROCESSING Development of a Kinetic Model for the Aromatisation of Propane and Propene over H-ZSM-5 Catalyst under Deactivating Conditions Nguyen Huu Luong Vietnam Petroleum Institute Dmitry B Lukyanov University of Bath, Department of Chemical Engineering Abstract A kinetic model has been developed for the aromatisation of propene and propane over fresh and deactivating catalyst at 500oC It was shown that under the same reaction conditions, propene is converted much faster than propane, and that the deactivation of catalyst in propene aromatisation is also much faster than that in propane aromatisation Analysis of the results of kinetic modelling together with the experimental data has indicated that C4+= alkenes are the species which are mainly responsible for the H-ZSM-5 catalyst deactivation in propene and propane aromatisation reactions Also, it has been shown that the catalyst deactivation rate depends strongly on the initial conversion of propane and propene, indicating the importance of the selection of the reaction conditions for testing catalyst deactivation associated with coke formation Introduction Stability of catalysts is of vital importance for their commercial applications Unfortunately, coke formation always occurs in processing hydrocarbons over solid acid catalysts [1] For example, in fluid catalytic cracking, the catalyst is partially deactivated only after a few seconds in the reactor In alkane dehydrogenation and aromatisation reactions, the deactivation proceeds during hours and days, respectively To enhance the catalyst performance, it is essential to understand the reasons for deactivation and to describe and predict the deactivation rate under different reaction conditions The conversion of light alkanes, as well as light alkenes, into aromatics is an important reaction from both the academic and industrial points of view Aromatisation of propane and/or n-butane leads to formation of the higher value aromatic hydrocarbons, which are valuable intermediates in the chemical and petrochemical industries The medium pore zeolite ZSM-5 appears to be the most 74 PETROVIETNAM - JOURNAL VOL 6/2011 PETROVIETNAM effective for this reaction [2] The reaction of light alkane aromatisation over ZSM-5 catalysts can be represented as a four-step process (Fig 1) The aim of this work is to develop a kinetic model to describe quantitatively the aromatisation of propane and propene over fresh and deactivating H-ZSM-5 catalyst at 500oC Experimental H-ZSM-5 zeolite with a SiO2/Al2O3 ratio of 240 was used as a catalyst in this work Kinetic studies of propene and propane reactions were performed at 500oC The reactions were carried out at atmospheric pressure in a continuous flow micro-reactor with a feed of 50 and 100wt% of propene, and propane, respectively (N2 was used in the experiments with propene) Prior to the catalytic experiments, the catalyst samples were activated under N2 flow (30ml/min) at 500oC for 4h Reaction products were analysed by on-line GC equipped with two detectors: TCD (analysis of H2) and FID (analysis of hydrocarbons) Different levels of conversions were obtained by performing experiments at different weight hour space velocities (WHSV) which have been checked for satisfaction of the reaction occurring in a kinetic regime In our investigated conditions, at a certain space velocity, changes in flow rate and catalyst amount not have any considerable effect on our experimental results, hence, mass transfer limitation can be ignored Result and Discussion Propane aromatisation is a complex heterogeneous reaction that involves many individual reaction species and many more chemical reactions To reduce the complexity of the reaction system, 13 components, which represent all reaction species involved in the aromatisation of light alkanes, were formed: alkanes (C1 – C6+) (subscript denotes the number of carbon atoms in the component molecule), alkenes (C2= – C6+=), aromatic component (A), and H2 (hydrogen) For numerical integration of the system of differential equations that describe the dependence of mass fractions of these components on contact time, the fourth-order Runge Kutta method was applied A detailed procedure of the estimation for rate constants of the reaction steps over fresh catalyst has been presented in our previous paper [2] 3.1 Propane and Propene Aromatisation over Fresh HZSM-5 at 500oC The agreement between the modelling results and experimental data is shown in Fig for the conversions of propane and propene over H-ZSM-5 at 5000C It can be seen that the kinetic model describes the experimental data quantitatively As expected, the conversion of propane or propene increases with contact time From Fig 2, it is shown that the conversion of propene is much faster than that of propane This can be understandable Fig Propane (a) and propene (b) aromatisation over fresh H-ZSM-5 at 500oC Experimental data (points) and calculated curves for the conversion as a function of 1/WHSV PETROVIETNAM - JOURNAL VOL 6/2011 75 PETROLEUM PROCESSING Fig Propane (a) and propene (b) aromatisation over fresh H-ZSM-5 at 500oC Experimental data (points) and calculated curves for the concentrations of C1-C4 alkanes, C2=-C4= alkenes, C5+ aliphatic hydrocarbons, and aromatics as functions of 1/WHSV because in the case of propene reaction, the availability of alkenes in the reaction mixture is much higher and alkenes are highly reactive species and directly participate in the alkene aromatisation steps [9-11] As a result, propene and other alkenes quickly react to form aromatics and by-products In our previous paper [2], it was shown that concentrations of alkenes are increasing with contact time at the beginning stage of the process, but are decreasing once aromatics are formed due to the consumption of alkenes in the alkene aromatisation steps This feature is also observed in propene aromatisation, even to a higher extent due to its higher reactivity of aromatic formation This is demonstrated in Fig It can be seen that the profile of concentrations of C2-4= alkenes peaks at very low contact time, and then decreases quickly with contact time In addition, it is worth noting that the percentage of alkanes formed as by-products of the reaction is considerable compared to the desirable product aromatics, leading to a low selectivity to aromatics These alkanes, excluding unreacted alkane feed and methane, are mainly formed from the hydrogen transfer steps in the stage of alkene aromatisation over acid sites [2, 10] This is one of the reasons leading to the limitation of aromatics selectivity for the reaction over H-ZSM-5 catalyst It can be explained that a higher extent of aromatisation in propene aromatisation concurrently results in a larger amount of alkanes formed, leading to a lower selectivity to aromatics 76 PETROVIETNAM - JOURNAL VOL 6/2011 3.2 Deactivation of H-ZSM-5 catalyst in Propane and Propene Reactions at 500oC To examine the deactivation of H-ZSM-5 catalyst we performed TOS experiments at different levels of initial propane and propene conversions The results obtained in these experiments were shown in Fig As expected, conversion of propane or propene is decreasing with time on stream due to coke formation It can be seen that the deactivation during propene aromatisation occurs much faster than during propane aromatisation This is understandable because in propene aromatisation, the availability of alkenes in the reaction mixture, which are considered to be coke precursor, is much higher than in propane aromatisation (Fig 3) Analysis of kinetic modelling results together with experimental data has also indicated that C4+= alkenes are the species, which are mainly responsible for catalyst deactivation in propene and propane aromatisation reactions In addition, C4= alkenes were also suggested to be coke precursors in the aromatisation of n-butane over Zn-modified MFI-type zeolite catalyst [5] It is worth noting the decrease in the extent of catalyst deactivation at high initial conversions, especially in propene aromatisation It is shown that the highest deactivation rate is observed at initial conversions around 50%, the deactivation rates at higher conversions (above 80%) are significantly lower This could be explained as follows At high conversions, most of the C4+= alkenes, PETROVIETNAM Fig Experimental data (points) and modelling curves for conversions of propane (a) and propene (b) as functions of TOS at different initial conversions (C4+= as coking species) Mass fraction (wt/wt) 80.0 40.0 Time on stream (h) Fig demonstrates that an excellent quantitative agreement has been obtained between the experimental and final kinetic modelling data on the deactivation of H-ZSM-5 catalyst in conversions of propane and propene This result is quite significant, since the catalyst deactivation in propene reaction is about 10 times faster than in the reaction of propane In spite of this difference, With propane as a feed, the highest deactivation rate is observed at initial conversions around 50%, the deactivation rates at higher conversions (above 80%) are significantly lower (5 - 10 times) Interestingly, practically no deactivation is observed for propane reaction during 50 hours on stream at the initial conversion around 6% In the case of propene reaction, situation is similar but not the same Indeed, the deactivation at the initial conversions around 50% is much faster than deactivation at higher conversions (80 - 90%) However, relatively rapid deactivation (with propene as a feed) is observed also for initial conversions as low as - 6%, and this is different from the results obtained with propane which are considered to be coking species, have been consumed to produce aromatics and other by-products As a result, coke formation is low at very high initial conversions It can be concluded that catalyst deactivation rate depends strongly on the initial conversion of propane and propene, and hence, indicating the importance of the choice of reaction conditions for testing catalyst deactivation associated with coke formation Fig Propene aromatisation over deactivated H-ZSM-5 at 500oC Effect of coke formation on the butenes concentrations at different initial conversions: 78wt% (solid bar) and 22wt% (blank bar) the deactivation curves for both reactions (and for different conversion levels) are described with the same values of the deactivation constants, indicating the validity of our approach to the development of the kinetic model for these reactions As a result of catalyst deactivation, conversion of the feed and concentrations of aromatics and alkanes decrease with TOS However, effect of the deactivation on concentrations of alkenes is more complicated Depending on the initial conversion of the alkane, the concentrations of alkenes may decrease or increase with TOS At lower PETROVIETNAM - JOURNAL VOL 6/2011 77 PETROLEUM PROCESSING initial conversions, these alkene concentrations decrease with time on stream due to the consumption of these species in the coke formation reactions However, at higher initial conversions, these concentrations increase with increasing time on stream It can be explained that due to the decrease of the catalytic activity of the coked catalyst, the consumption of these species in the alkene aromatisation steps, and in the coke formation step as well, decreases As a result, the concentrations of these species in the reaction mixture increase This feature is more pronounced for propene aromatisation than for propane aromatisation (Fig 5) Conclusions The aromatisation reactions of light alkanes and alkenes have been studied over H-ZSM-5 catalyst at 5000C, and the kinetic model has been developed for these reactions This model describes transformation of propene and propane over fresh and deactivating catalyst at 500oC for a wide range of reaction conditions (different feed compositions and space velocities) It was shown that under the same reaction conditions, propene is converted much faster than propane, and that the deactivation of catalyst in propene aromatisation is also much faster than that in propane aromatisation It is important to note that the model describes deactivation processes with significantly different characteristic times (hours and tens of hours for propene and propane reactions, respectively) Analysis of the kinetic modelling results together with the experimental data has indicated that C4+= alkenes are the species, which are mainly responsible for the H-ZSM-5 catalyst deactivation in propene and propane aromatisation reaction Also, it has been shown that the catalyst deactivation rate depends strongly on the initial conversion of propane and propene, indicating the importance of the choice of the reaction conditions for testing catalyst deactivation associated with coke formation n-Butane Aromatization over H-ZSM-5 Catalyst Chemical Engineering Science 61, 5881-5894 Fricke, R., Kosslick, H., Lischke, G., Richter, M., 2000 Incorporation of gallium into zeolites: syntheses, properties and catalytic application Chemical Reviews, 100, 2303-2405 Guo, J., Lou, H., Zhao, H., Zheng, L., Zheng, X., 2005 Dehydrogenation and aromatization of propane over rhenium-modified HZSM-5 catalyst Journal of Molecular Catalysis A: Chemical, 239(1-2), 222-227 Jana, A K., Rao, M S., 1994 Selective aromatisation of C3 and C4 paraffins over modified encilite catalysts Coking mechanism and deactivation kinetics of n-butane aromatisation Industrial and Engineering Chemistry Research, 33, 600-606 Choudhary, T V., Kinage, A., Banerjee, S., Choudhary, V R., 2006 Influence of Si/Ga and Si/Al ratios on propane aromatization over highly active H-GaAlMFI Catalysis Communications, 7(3), 166-169 Kwak, B S., Sachtler, W M H., Hagg, W O., 1994 Catalytic conversion of propane to aromatics: effects of adding Ga and/or Pt to HZSM-5 Journal of Catalysis, 149, 465-473 Li, W., Yu, Y., Meitzner, G D., Iglesia, E., 2001 Structure and properties of cobalt-exchanged H-ZSM-5 catalysts for dehydrogenation and dehydrocyclisation of alkenes Journal of Physical Chemistry B, 105, 1176-1184 Lukyanov, D B., Gnep, N S., Guisnet, M R., 1994 Kinetic modeling of ethene and propene aromatisation over HZSM-5 and GaHZSM-5 Industrial and Engineering Chemistry Research, 33, 223-234 10 Lukyanov, D B., Gnep, N S., Guisnet, M R., 1995 Kinetic modeling of propane aromatisation reaction over HZSM-5 and GaHZSM-5 Industrial and Engineering Chemistry Research, 34, 516-523 Karge, H G., 2001 Chapter 16: coke formation on zeolites In: van Bekkum, H., Flanigen, E M., Jacobs, P A., Jansen, J C (Eds.), Introduction to Zeolite Science and Practice, 2nd Completely Revised and Expanded Edition, Studies in Surface Science and Catalysis, 137, 707-746 11 Lukyanov, D B., 1999 Development of kinetic models for reactions of light hydrocarbons over ZSM-5 catalysts Experimental studies and kinetic modelling of ethene transformation and deactivation of HZSM-5 catalyst In: Froment, G F., Waugh, K C (Eds.), Reaction Kinetics and the Development of Catalytic Processes, Studies in Surface Science and Catalysis, 122, 299-306 Nguyen, L H., Vazhnova, T., Kolaczkowski, S T., and Lukyanov, D B., 2006 Combined Experimental and Kinetic Modelling Studies of the Pathways of Propane and 12 Buchanan, J S., Santiesteban, J G., Hagg, W O., 1996 Mechanistic considerations in acid-catalyzed cracking of olefins Journal of Catalysis, 158, 279-287 References 78 PETROVIETNAM - JOURNAL VOL 6/2011 PETROVIETNAM PETROVIETNAM NEWS PVEP concludes a $200 million term loan facility with Vietinbank oice The facility was signed by PVEP President & CEO Mr Nguyen Vu Truong Son and Vietinbank Ha Noi branch General Director Mr Nguyen Van Thang According to the signed agreement, Vietinbank commits to extend a year term loan of US$200 million to inance the second phase of Dai Hung ield development Project, run by Petrovietnam Domestic Exploration Production Operating Company (PVEP POC) Vietinbank commits to extend a year term loan of $200 million to finance the second phase of Dai Hung field development Project Photo: Manh Thang O n 24 May 2011, Petrovietnam Exploration Production Corporation (PVEP) and Vietnam Joint Stock Commercial Bank for Industry and Trade (Vietinbank) - Ha Noi Branch coorganize a signing ceremony for a US$200 million term loan facility at Petrovietnam’s head- Dai Hung ield belongs to Block 05-1(a) in Nam Con Son Basin, ofshore the continental shelf of Southern Viet Nam The plan to develop the Dai Hung ield Phase II has been approved by Vietnamese Prime Minister based on its reserves and economic eiciency as well as the national energy security strategy This project is expected to contribute substantially to PVEP in particular and Petrovietnam in general in accomplishing their production targets in  years ahead Huong Thu Petrovietnam chooses US consulting irm for power project T he US-based Black & Veatch will provide project management and design services for the 1,200 MW Long Phu Power Plant in southern Soc Trang Province, its contractor, Petrovietnam Technical Services Corporation (PTSC), said on 26 May 2011 “Apart from engineering and project management consulting experience, Black & Veatch has experience as an EPC (Engineering, Procurement and Construction) contractor in the power sector, which is of great importance in assisting PTSC with the engineering and construction of the power plant” - Nguyen Tran Toan, Deputy General Director of PTSC, said PTSC is a subsidiary of Petrovietnam, the investor, and is the engineering, procurement, and construction contractor for the plant Petrovietnam POWER Corporation (PV Power), another subsidiary, will operate the plant “PTSC’s strong technical capabilities and their leadership in oil and gas combined with Black & Veatch’s design and implementation knowledge is an example of how international partnerships can deliver innovative, quality solutions to meet Viet Nam’s growing power needs” - Mr Gary Morrow, the US irm’s Vice President and Director of Power Generation Services said Long Phu will be a coal-fueled facility and use the highly eicient super-critical technology Super-critical technology achieves lower carbon and other emissions than sub-critical plants of the same power output because it enables plant operators to use less fuel per unit of electricity generated The plant will also install wet scrubbers and electrostatic precipitators for controlling emissions The facility will consist of two 600 MW units It will be the irst of three planned power plants at the Long Phu Power Center which will have a total capacity of 4,400 MW The Government has announced plans to build about 90 coal-ired plants by 2025 at a cost of US$83 billion and a combined capacity of 106,000MW Petrovietnam plans to add 9,000MW of power generation capacity by 2015 Ha Phong PETROVIETNAM - JOURNAL VOL 6/2011 79 NEWS PVEP to participate in Block 39 License Contract in Peru R ecently, in Lima, the Republic of Peru, Petrovietnam Exploration Production Corporation (PVEP) and Burlington Resources Peru Limited, Sucursal Peruana, a subsidiary of ConocoPhillips, jointly celebrated the signing of the Asset Sale and Purchase Agreement relating to Block 39 License Contract, which was concluded on 24 March 2011 By signing this ASPA, Burlington Resources Peru Limited, Sucursal Peruana shall transfer all of its interests in respect to Block 39 to PVEP The transaction is still subject to Peru governmental approvals, which are expected to be obtained in the coming weeks This is the third exploration project of PVEP so far in Peru Block 39 is located in Marañon Basin, covering an area of 8,868 km2 across the Maynas province, in Peru The License Contract for this block was initially signed by Peruvian national oil company PeruPetro and Repsol Exploración Peru, sucursal del Peru as the operator Reliance Exploration & Production DMCC, Sucursal del Peru also participates, in addition to Repsol Exploración Peru, sucursal del Peru and Burlington Resources Peru, Sucursal Peruana Leaders from the contractual parties at the ceremony Photo: PVEP The conclusion of this agreement would be a signiicant step for PVEP to approach South America petroleum market, in an efort to expand the operation internationally toward implementing its development strategy By entering into this deal, PVEP also hope to contribute substantially to the development of cooperation relationship between the two countries, Vietnam and Peru Thu Huong PVFCCo launches a new fertilizer brand - Phu My NPK tionwide and organizing workshops to introduce this new product to its sales agents and farmers This new product launching visualizes the company’s product diversiication strategy and contributes efort to decrease the lack of high quality NPK products in the market Workshop on “Introduction and implementation of Phu My NPK sale program” Photo: Thai Son P etrovietnam Fertilizer and Chemicals Corporation (PVFCCo) has launched a new product line - NPK synthetic fertilizer beside the core existing Phu My urea “Phu My NPK” was produced at Japan Vietnam Fertilizer Company under the order of PVFCCo Phu My NPK will be distributed to the domestic market from the middle of June 2011 with initial estimated market consumption of 36,500 tons from now to the end of this year PVFCCo has been taking many experimental models on rice, industrial, fruit trees with 16-16-8-13S “Phu My NPK” used na80 PETROVIETNAM - JOURNAL VOL 6/2011 The launch of 16-16-8-13S “Phu My NPK” is also the irst step of the pre-marketing process for the future NPK product range of Phu My NPK plant invested by PVFCCo at Phu My industrial zone, next to Phu My Urea plant Phu My NPK plant has a production capacity of 400,000 tons/year and a total investment of about US$ 63 million The plant will use advanced technology to produce high quality one-grained NPK PVFCCo plans to kick of the project in the 3rd quarterly of this year and complete the construction in 2013 Thuy Nguyen The new fertilizer brand “Phu My NPK” with its formula of 16-16-8-13S is packaged in 50kg/unit and produced with modern technology It was a white crystalline solid containing chemical elements including nitrogen (N), phosphorus (P), potassium (K), and an additional sulfur (S) in each unit This formula is more preeminent than that of mixing mentioned elements separately, normally called “3 color NPK” PETROVIETNAM OIL & GAS GLOBAL MARKET Global Oil supply increased again in May, jumping by 337,000 barrels per day to average 88.8 million b/d, according to PIW’s preminary While supply in the first half of 2011 looks to have been sufficient to meet demand, serious concerns raise over the shape of balances for the remainder of the year PIW estimates that global supply and global demand virtually neck and neck between January and May at roughly 88.67 million b/d For the last seven months of 2011, the balance will obviously depend on the situation in Libya, and how effective Saudi Arabia and its allies in OPEC compensate the lost Libyan barrels Last month’s jump in output reflected an increase in supply from both OPEC and non-OPEC producers, despite the ongoing disruption in Libya and the start of seasonal maintenance work in the North Sea and North America Crude oil prices (from Apr.18 to Jun.8, 2011-$/barrel) Sources: PIW Reuters PETROVIETNAM - JOURNAL VOL 6/2011 81 NEWS Oil products prices * First 10 days; Sources: Reuter, PIW LPG prices (US$/ton) * Notes: CP = Contract Price; Sources: LPGW Asia Pacific LNG prices (US$/mm BTU) Note: cif corrected; Sources: WGI 82 PETROVIETNAM - JOURNAL VOL 6/2011 PETROVIETNAM Natural gas prices (US$/mm BTU) ICE-London Nymex-New York Sources WGI Offshore Facilities and Equipment Market Oil import freight cost (US$ = USD) Drewry Shipping Consultants Ltd OGJ LPG Shipping rates Spot (US$/ton) PETROVIETNAM - JOURNAL VOL 6/2011 83 NEWS (US$1000/cal.month) - EA Gibson - LPGW Supply Vessels rates in the North Sea – (Pound/day) Source: Seabrokers Stavanger Supply Vessels rates in the Offshore West Africa - (US$/day) Source: Chart Shipping Barcelona Mai Trang (collected and edited) 84 PETROVIETNAM - JOURNAL VOL 6/2011 ... kaolinite 40 PETROVIETNAM - JOURNAL VOL 6 /2011 PETROVIETNAM Plate Sample 1 6-1 -B, at the interval of 2830m (croseds-nicols) Plate Sample 1 6-1 -B, at the interval of 2958.24m (croseds-nicols) Medium... poorly sorted and non-shaded zones as moderately sorted sands) Track - Electrofacies and Track 10 - Lithology 18 PETROVIETNAM - JOURNAL VOL 6 /2011 PETROVIETNAM Mud rip-up clast-rich sandstones (MCSt):... rock permeability PETROVIETNAM - JOURNAL VOL 6 /2011 39 PETROLEUM EXPLORATION & PRODUCTION Plate Sample 1 6-1 -B, at the interval of 2325.00m (crossed-nicols) Plate Sample 1 6-1 -A, at the interval