1 MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF MINING AND GEOLOGY Nguyen Tran Tuan STUDY ON THE RESONABLE HORIZONTAL DRILLING TECHNOLOGY TO RECOVER METHANE GAS IN MAO KHE UNDERGROUND COAL MINE Major: Petroleum Engineering Code: 62.52.06.04 SUMMARY OF DOCTORAL THESIS IN ENGINEERING HANOI - 2014 2 The research has been accomplished at Department of Drilling and Production, Faculty of Oil and Gas, Hanoi University of Mining and Geology Supervisors: 1. Assoc.Prof. Dr. Tran Dinh Kien 2. Dr. Nguyen Xuan Thao Examiner 1: Assoc.Prof.Dr Truong Bien Vietnam Aschnology Examiner 2: Dr Khuou Huu Bo University of Transport and Communications Examiner 3: Dr Nguyen Xuan Toan Vietnam National Oil and Gas Group This thesis is going to be defended at the committee of doctorate thesis examiners of Hanoi University of Mining and Geology on date month year 2014 This thesis can be found at Hanoi National Library or Library of Hanoi University of Mining and Geology 3 Introduction 1. The necessity of thesis In recent years, a number of mines in Quang Ninh has occurred the large gas explosion causing percussionage to people and property such as Mao Khe Coal Company in 1999 which killed 19 people, two consecutive gas explosion at Khe Cham II coal Enterprise and 909 coal exploitation Enterprise in 2002 that killed 13 people. March 2006, the Thong Nhat coal Company had happened coal methane explosion that killed 8 people and the most recent gas explosion at Khe Cham Coal Company December 9, 2008 in which there were 11 deaths. Along with the application of traditional methods of ventilation to reduce the concentration of methane gas in the mine to a safe level; Mao Khe mine has also started to apply the methods of drilling boreholes in different directions to remove methane in the coal seams in the mining production areas as well as in cover stone. In fact, drilling long horizontal boreholes are low effect and it is not reach to the design length, the reasons are mainly due to lack of choice of drilling method and drilling technology which is suitable with the purpose of removing mine methane. Therefore, the study in the choice of drilling method, appropriate horizontal drilling technology to remove gas through the boreholes in Mao Khe mine in accordance with the geological and exploitation conditions in the mine to ensure the safety of Mao Khe, pollution reduction is needed with scientific and practical to meet the production demand of Mao Khe mine in particularly as well as in other mines in Vietnam. 2. The purpose of this study 4 The study is the research in methods and choice of horizontal drilling technology to remove methane in Mao Khe mine to ensure safety in production operating. The results of this study will be scientific and practical basic application in remove gas in other coal mine in Vietnam. 3. The objects and margin for research - The object of study: selection in horizontal drilling technology of rotary – percussion drilling equipment RPD-130SL- F2W and the kits of sample threading drilling PS-89 to drill horizontal boreholes for removing gas in accordance with geological and exploitation conditions in Mao Khe coal mine. - The sphere of study: study in the characterization of horizontal drilling technology; rotary – percussion drilling technology in the geological conditions of the Mao Khe coal mine, the influence of these technologies to drilling rate. 4. Detail of the study - Study from the technical documents which relate to global and domestic drilling for remove gas. - Study on the characterizations of horizontal and rotary – percussion by sample threading drilling technology for horizontal boreholes for methane removing in coal pit mines. - Testing of rotary – percussion drilling of horizontal boreholes in actual conditions of the Mao Khe mine. Base on the theoretical and testing results to select the appropriate value of parameters in horizaontal rotary – percussion drilling for methane removing as well as define the efficiency of this method in the Mao Khe coal mine. 5 5. Research methods - Collect, research, and analysis of data related to the field of study; - Experiment in real conditions; monitoring and collecting real data about rotary - percussion drilling technology in horizontal drilling for gas escape in Mao Khe mining conditions; - Application of statistical mathematic methods to analysis the actual monitoring data for selection of appropriate horizontal drilling technology. 6. Scientific and practical meaning - Scientific meaning: The study on application of rotary – percussion drilling technology using RPD -130SL – F2W drilling equipment and the kit of sample threading drilling tool PS -89 to drilling horizontal boreholes for gas off in Mao Khe coal mine is not only overcome the disadvantages of rotary drilling methods but also improve the drilling rate and the gas removable. The results are the scientific basic as well as justification for the selection of gas removing technology in coal pit mine in Quang Ninh. - Practical meaning: the selection of appropriate drilling parameters in horizontal drilling using RPD – 130SL – F2W and PS – 89 for in Mao Khe mine that increase the efficiency of rotary drilling and gas removing are necessary and respond promptly to the current demand in methane remove. 7. The new conclusion of thesis The study proposed the application of horizontal drilling technology to remove methane in pit coal mines in Mao Khe by rotary – percussion drilling method and sample threading pipe drilling technology instead of conventional rotary drilling. 6 Experiment in production conditions, selection of reasonable the rotary – percussion drilling parameters to drill horizontal boreholes for removing methane in Mao Khe mining conditions. 8. The protective contentions - Application of rotary - percussion drilling technology by RPD-130SL-F2W and kits of sample threading drilling pipe PS-89 to remove gas from horizontal boreholes in Mao Khe mine is reasonable and it is suitable with the geological conditions as well as the current demand of gas removed. - Horizontal drilling with rotary – percussion drilling equipment - RPD-130SL-F2W and kits of sample threading drilling pipe PS-89 has the average speed of a mechanical increasing from 1.45 times to 1.7 times and reducing the energy for rock destroyed from 70% to 51% in cooperation to rotary drilling method in the same conditions. 9. The database of thesis The thesis bases on the final report documents the geological exploration and the coal production documents of Mao Khe Coal Company, Vietnam Coal and Minerals Group as well as the member companies. The study also uses the technical documents which relate to the content of research as well as the articles and scientific studies of the authors published in the domestic and international journals. 10. The content and structure of thesis The thesis consists of an introduction, four chapters study the content, conclusions, recommendations and a list of publish articles of author and the references. The entire contents of the thesis is presented in 138 pages of A4, font size of 14 in Time New Roman, Unicode, including 58 figures, 27 tables and appendices. 7 CHAPTER 1 OVERVIEW OF GAS REMOVE IN PIT COAL MINE TECHNOLOGY IN OVER THE WORLD AND IN VIETNAM 1.1. The requirement of methane recovery from pit coal mine in over the world. Today, science has confirmed the released methane gas from coal mines entering the atmosphere is one of the main causes the environmental pollution and the greenhouse effect. However, in positive perspective, the methane itself is energy resource for human, for the chemical industry, boilers, and industrial furnaces, used for production power. Thus, in the coal mining industry, if the technology of methane recovery is suitable methane will be a precious energy resource, and the recovery of methane released during mining will contribute actively eliminate fire hazards and minimize mining causing environmental pollution. 1.2. The technology of methane removable drilling in the pit coal mine in over the world. Today, there are two technology mainly used for removing and recovery methane from the coal mine: through the boreholes which is drilled from the surface and through the boreholes drilled from the pit mine. 1.3. The status of research and application of methane removing drilling technology. The research and application of methane removing drilling technology in Vietnam in general and in Khe Cham, Mao Khe in particular is just in beginning period, there is no scientific work published. Thus, the study of selection appropriate drilling technology for gas removing in Mao Khe geological conditions as 8 well as other mines in Quang Ninh province is necessary in science and practical. CHAPTER 2 GEOLOGICAL CHARACTERIZATIONS, MINING STATUS AND POTENTIAL FOR METHANE GAS IN MAO KHE COAL MINE 2.1. Geology, physic and chemical characterizations 2.1.1. Geology structure. Geology structure of Mao Khe coal mine is in Quang Ninh sedimentary strata and divided into two clearly block North – South by a fault [15]. 2.1.2. Constructive characterization and faults system. The constructive characterization of the mine is rips and faults. There are totally 18 faults along the direction of the mine and some of them in South West direction 2.1.3. Physical characterization of rocks. The research of strata has showed that the geological structure of the Mao Khe is quite similar with Quang Ninh mine area. The magma is distributed in right general layers. Coal, claystone and siltstone near the coal reservoir form walls, coal pillars. On the other side, sandstone and others are far from the reservoir. 2.2. Characteristic and the nature of Mao Khe coal mine. The coal seams in Mao Khe coal mine were highly degenerated and the color of coal change between black and dark grey. Coal is relatively hard, and the hardness in drilling levels from III-V; hardness f-level is usually greater than 2; density from 1.55 to 1.70 g/cm3. Common minerals in coal samples are arghilit, silica oxit. 9 2.3. Current status of coal exploitation and the potential of methane in Mao Khe. 2.3.1. Current status in exploitation of Mao Khe. Today, Mao Khe is in production from two wings which includes 9b West, level -80/25, V8 West, level -80/+30, V8 East, level -150/-80, V7 Đ.TR, level -80/-25; V6 W level -80/-25; V6 Đ.TR level -80/-25; V6 ĐMR level -80/-25 in the North side and 8CN-ĐN II, level -80/LV; V.8 CB-ĐN I, level -80/+25 in the South. 2.3.2. Methane potential in Mao Khe coal mine. According to the results from the research of experts [1, 4, 12, 22, 35, 36], the classification of gas existing in coal seams and side walls depends on the forming conditions of the mine as below: - Gas in free form exists in the fractures, pores of the reservoir - Gas exists in the form of adhesion, sustainability chemical and physical link and usually coming out from the coal when under external force such as beating, crushing, etc. - Gas exists in connate water in the reservoir. 2.3.3. Safety solutions to prevent methane appearance in pit. In the current period, along with the application of appropriate ventilation system, Mao Khe mine has been studying the application of drilling technology to remove methane from coal seams, or areas containing methane and other toxic gases. Chapter 3 Study in selection of appropriate technology of horizontal drilling to remove methane in Mao Khe coal mine 10 3.1. Characteristic of horizontal drilling 3.1.1. The lost of axial load on rock destroying Figure 3.1 Shape of drilling pipe is compressed in drilling horizontal boreholes The axial load on drill bit is actually defined as below: P k = P o - P c - P t (3.4) Where: P k : actual axial load on drill bit, N; P o : maximum allowance load of drilling head, depends on technical characteristic of drilling machine, N; P c : weight of drilling pipe, N. 3.2.1. Curving and oblique of horizontal boreholes. 3.1.3. Difficulties in horizontal drilling. o Figure 3.4. Curving borehole due to eccentric drilling equipment Figure 3.5. Direction of curving borehole Figure 3.6. Ability of borehole deflected when meet rock in different hardness Figure 3.7. Deflection of borehole when drilling in coal zone [...]... of bits 3.2.3 The selection of drilling method and technology for gas removing in Mao Khe 3.2.3.1 The selection drilling method Base on the characteristic of horizontal drilling as well as the requirement of gas removing in Mao Khe; this study has the selection of rotary – percussion drilling technology for methane of in Mao Khe coal mine The equipment will be used for drilling is RPD – 130SL – F2W... diagram in borehole is described as in Figure 3.10 1 a 2 Figure 3.10 Grooving diagram in horizontal borehole Figure 3.11 The effect of drilling pipe on the lower side of borehole while drilling 3.2 Study on the appropriate selection of horizontal drilling technology for removing methane in Mao Khe mine 3.2.1 Status of methane removing drilling in Mao Khe Base on the development plan as well as the potential... Sandstone IXX, Ps= 5000 7000 MPa 4.4 The effective of drilling for gas off in 9 East swing level – 80 According to the results of monitoring methane concentrations appear in the ventilation of the longwall before removing gas 9D at the highest of 1.62 % , averaging 0.73 %, and the lowest at 0.54 % , often exceeded the warning level, power interruptions After removing gas by horizontal drilling holes, the. .. reduce stopping times for warnings or power, that increases production of longwall mining up to 33.4 % At the same time, the 23 costs for longwall ventilation decreased 30.4 % compared to the non application of the system for gas removing [6, 7] CONCLUSION AND RECOMMENDATION CONCLUSION According to the results of the study, I am going for some below conclusion: 1 Stratigraphy of Mao Khe coal mine is sedimentary... permeability and the characteristic of gas storage in coal seams as well as in the rock surrounding Therefore, the choice of appropriate research methods to remove gas with the geological conditions, the mine operation conditions in Mao Khe to ensure safety in mining and environmental protection is necessary, with scientific meaningful and practices 2 The selection of rotary – percussion drilling technology. .. system for gas off RECOMMENDATION Recommendation of application of rotary – percussion drilling technology and sample threading drilling as well as the results of this study to drilling horizontal boreholes for methane off in some pit mine need removing methane which has the same conditions with Mao Khe In application process, it need to research to complete rotary – percussion drilling technology, ...11 In general, the difficulties in horizontal drilling are similar with vertical drilling Boreholes in horizontal drilling do not actually have water column and rarely using clay based mud in drilling It therefore always prone to collapsing along the upper boreholes Figure 3.8 Shape of upper boreholes Figure 3.9 Cover rock status in in horizontal drilling in fracture zone horizontal drilling boreholes... transmit to drill bit from 7000 – 9000 with rotary rate = ; percussion frequency 3 The efficiency of methane remove in longwall mines 9Đ Mao Khe mine by drilling horizontal holes is averagely at 36.2% Thus increasing efficiency production time from 5% - 10%, resulting in production in longwall has increased to 33.4% And the costs for longwall ventilation decreased 30.4% compared to the non application of the. .. Position of the holes in preparation for mining at 9Đ seam Figure 3.13: Boreholes structure for gas recovery in 9Đ seam The number of the boreholes in production area will be defined as below: n Q Q MT (3.19) Q: volume of gas in production area of longwall QMT: volume of recovery methane flow at the long wall, 3 m /month 14 3.2.2 The basis of horizontal drilling technology for methane removing in Mao Khe. .. Proceeding of the 20th Scientific & Engineering mining, Vung Tau, pp.182-186 4 Nguyen Xuan Thao, Nguyen Tran Tuan (2004), Study on the gas drainage drilling technology to recovery Methane gas and prevention of explosion in Quang Ninh underground coal mines,Bulletine of Mining Science and Technology, Vol 7, Ha Noi, pp.22-25 5 Nguyen Xuan Thao, Nguyen Tran Tuan, Nguyen Tu Vinh (2004), Study on the water . OF EDUCATION AND TRAINING HANOI UNIVERSITY OF MINING AND GEOLOGY Nguyen Tran Tuan STUDY ON THE RESONABLE HORIZONTAL DRILLING TECHNOLOGY TO RECOVER METHANE GAS IN MAO. Quang Ninh province is necessary in science and practical. CHAPTER 2 GEOLOGICAL CHARACTERIZATIONS, MINING STATUS AND POTENTIAL FOR METHANE GAS IN MAO KHE COAL MINE 2.1. Geology, physic and. Nguyen Xuan Toan Vietnam National Oil and Gas Group This thesis is going to be defended at the committee of doctorate thesis examiners of Hanoi University of Mining and Geology