10 horizontal drilling

Well Drilling Engineering Horizontal Drilling Dr DO QUANG KHANH Horizontal Drilling        Why Drill Horizontal Wells? Relative Production Rates Relative Costs Types of Horizontal Wells Drilling Problems & Solutions How Popular is Horizontal Drilling? Examples Why Drill Horizontal Wells?  Increase Reserves  Increase Production Rates  Control Water Production  Control Gas Production Why Drill Horizontal Wells?  Control Sand Production  Produce From Thin Reservoirs  Connect Vertical Fractures  Produce Methane from Coal Seams  Increase Injectivity - (steam, water, polymers, etc.) 10 Summary • Horizontal wells may produce at 3-5 times the rate of vertical wells in the same area (… as much as 20 times higher in special cases) • Horizontal wells typically cost 1.5-3 times as much as vertical wells in the same area • Horizontal wells are often very attractive in formations with extensive vertical fractures 22 Summary • The use of horizontal wells has been growing - worldwide • Horizontal wells has increased our recoverable reserves • In the U.S one rig in ten is drilling horizontal wells (1994) (1998) • Today ~ one rig in fifteen is drilling horizontal wells (2002) 23 24 25 Long - Radius Wells • Used for achieving large horizontal displacements from platforms or drilling pads • Used for achieving very long horizontal sections (to 6,000 ft +) Build Rate: ~ 2-6 degrees/100 ft Build Radius: ~ 1,000-3,000 ft Length of Horiz Section: 1,000 - 8,000 ft (1995) 26 Method: • Use conventional directional drilling technology • Use rigid bottom hole assemblies, motors & bent subs, stabilizers • or Use Navigation drilling systems with “steerable” drilling motors 27 Medium - Radius Wells Build Rate: ~ - 20 degrees/100 ft (up to 40 deg/100 ft in some cases) Build Radius: ~ 300 - 700 ft Length of Horiz Section: 1,000-6,000 ft 28 Method: • Use modified long-radius drilling technology • Use different motors for Angle Build and Angle Hold sections • Use a “Tangent Section” between the two build sections • Use compressive service drillpipe through the curve if Build Rate > 15 deg./100 ft (CS drillpipe has integral wear knots every ~ 10 ft) 29 Short-Radius Wells Build Rate: Build Radius: ~ - degrees/ft ~ 20 - 40 ft Length of Horiz Section: 200 - 1,000 ft 30 Method:  Two downhole motor designs are available  Drill vertical “rathole” to identify horizon  Build angle with special curve-drilling assembly with a non-rotating shell that gives curvature to the tool  After building angle to horizontal, use a special angle-hold assembly: this consists of two undergauge stabilizers behind the bit, and flexible drillpipe 31 32 Horizontal Well Pair 33 Horizontal Well Pair 34 Vertical Injection Wells and Horizontal Production Well 35 36