TẬP ĐOÀN DẦU KHÍ VIỆT NAM TRƯỜNG ĐẠI HỌC DẦU KHÍ VIỆT NAM Drilling Problems Seminar on April Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Outline Problems • Pipe Sticking • Pipe Failure • Borehole Instability • Lost Circulation • Hole Deviation • Formation Damage • Mud Contamination • Equipment & Personnel Related • Abnormal High Pressure Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Pipe Sticking • Definition: pipe is called stuck if it can not be freed or pulled out of the hole with out damaging and exceeding the rig’s maximum allowable hook load.(is the situation when drilling string become stuck due to either mechenical problems or differential-pressure pipe sticking) • Classification: There are two types of pipe sticking • Differential-pressure pipe sticking • Mechanical pipe sticking Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Differential Pipe Sticking • Differential pipe sticking: occurs when a portion of drillstring become embedded in a mud-cake • Causes: • The mud pressure, Pm, which acts on outside wall of the pipe, is greater than the formation-fluid pressure, Pff, Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Differential Pipe Sticking • Causes • Long or oversized drill collar strings • Deviated hole • Poor mud quality • Interruption of pipe movement, circulation Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Differential Pipe Sticking • Solution • Precaution • Maintain the lowest continuous fluid loss • Maintain the lowest level of drilled solids in the mud system or remove all drilled solid • Use the lowest differecial pressure with allowance of swab and surge pressures during tripping operation • Select a mud system will yield a smooth mudcake ( low coefficient of friction) • Maintain drillstring rotation at all time if possible • If sticking does occur • The driller first tries to free pipe by jarring with a jar in drillstring • Freeing stuck pipe include mud-hydrostatic-pressure reduction in annulus, oil spotting around the stuck and washing over stuckpipe Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Machanical Pipe Sticking • Machanical pipe sticking: caused by inadequate re- moval of drilled-cuttings from the annulus, borehole instabilities such as hole caving, sloughing or collapse, plastic shale or salt sections creeping, key seating. • Drilled-cuttings • Borehole instabilities • Keyseat • Causes: Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Mechanical Pipe Sticking Drilled cuttings Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Mechanical Pipe Sticking Pipe Sticking Pipe Failure Lost Circulation Borehole Instability Hole Deviation Mud Contamination Formation Damage Abnormal High Pressure Equipment & Personnel… Mechanical Pipe Sticking Borehole Instability [...]... drillstring, and inherently sloughing shale Problems associated with hole enlargement are an increase in cementing difficulty, potential hole deviation, hydraulic equipment for effective hole cleaning and potential problem during logging operations • Fracturing: occurs when the wellbore drilling- fluid pressure exceeds the formation fracture pressure The associated problems are lost circulation and possible... caused by fluid circulation, chemical caused by interaction of borehole fluid with formation • Types and associated problems: There are 4 types of bore hole instability: hole closure, hole enlargement, fracturing, collapse • Hole closure or narrowing: occurs in shale or salt section Associated problems are an increase in torque and drag, potential pipe sticking, difficulty of casing landing Borehole Instability... formation fracture pressure The associated problems are lost circulation and possible kick occurrence • Collapse Borehole collapse occurs when the drilling- fluid pressure is too low to maintain the structural integrity of the drilled hole The associated problems are pipe sticking and possible loss of well Borehole Instability Pipe Sticking Pipe Failure Borehole Instability Lost Circulation Hole Deviation... Circulation Hole Deviation Formation Damage Mud Contamination Abnormal High Pressure Equipment & Personnel… • Fishing tools use to retrieve fishes or junks which break off and fall down the well during drilling Bore Hole Instability Pipe Sticking Pipe Failure Borehole Instability Lost Circulation Hole Deviation Formation Damage Mud Contamination Abnormal High Pressure Equipment & Personnel… • Definition:... gradients Lost Circulation Pipe Sticking Pipe Failure Borehole Instability Lost Circulation Hole Deviation Formation Damage Mud Contamination Abnormal High Pressure Equipment & Personnel… • Solution • • Keep drilling if the geological condition allow In the case of severe lost circulations, use lostcirculation materials (LCMs) (video) Hole Deviation Pipe Sticking Pipe Failure Borehole Instability Lost Circulation... Failure Borehole Instability Lost Circulation Hole Deviation Formation Damage Mud Contamination Abnormal High Pressure Equipment & Personnel… • Causes of formation damage: • Contact with a foreign fluid ( Drilling mud, Clean completion fluid or work-over fluid, Well testing fluid ) • Sometimes even the reservoir fluid itself if the original characteristics are altered Formation Damage Pipe Sticking Pipe... Solids Contamination • Definition: solids are materials that are added to make up a mud system and materials that are drilled • Causes: • Excess solids of any type are the most undesirable contaminant to drilling fluids • They affect all mud properties Mud Contamination Pipe Sticking Pipe Failure Borehole Instability Lost Circulation Hole Deviation Formation Damage Mud Contamination Abnormal High Pressure... centrifuges • Shakers remove solids in the size of cuttings (approximately 140μ or larger) • Desanders remove solids in the size of sand (down to 50μ) • Desilters remove solids in the size of silt (down to 20 μ) Mud Contamination Pipe Sticking Pipe Failure Borehole Instability Lost Circulation Hole Deviation Formation Damage Mud Contamination Abnormal High Pressure Equipment & Personnel… Mud Contamination . wellbore drilling- fluid pressure exceeds the formation fracture pressure. The associated problems are lost circulation and possible kick occurrence • Collapse. Borehole collapse occurs when the drilling- fluid. exceeding the rig’s maximum allowable hook load.(is the situation when drilling string become stuck due to either mechenical problems or differential-pressure pipe sticking) • Classification: There. associated problems: There are 4 types of bore hole instability: hole closure, hole enlargement, fracturing, collapse. • Hole closure or narrowing: occurs in shale or salt section. Associated problems