PETROLEUM ENGINEERING 405 * Well Drilling Engineering Surge and Swab Pressures Dr DO QUANG KHANH * 15 Surge and Swab Pressures Surge and Swab Pressures Closed Pipe Fully Open Pipe Pipe with Bit Exampl[.]
Well Drilling Engineering Surge and Swab Pressures Dr DO QUANG KHANH 15 - Surge and Swab Pressures Surge and Swab Pressures Closed Pipe Fully Open Pipe Pipe with Bit Example General Case (complex geometry, etc.) Example READ: APPLIED DRILLING ENGINEERING Chapter HW # ADE # 4.52, 4.53, 4.54 Surge Pressure due to Pipe Movement When a string of pipe is being lowered into the wellbore, drilling fluid is being displaced and forced out of the wellbore The pressure required to force the displaced fluid out of the wellbore is called the surge pressure Surge Pressure due to Pipe Movement An excessively high surge pressure can result in breakdown of a formation When pipe is being withdrawn a similar reduction is pressure is experienced This is called a swab pressure, and may be high enough to suck fluids into the wellbore, resulting in a kick For fixed v pipe , Psurge Pswab v ae v a K c v p Surge Pressure - Closed Pipe Newtonian The velocity profile developed for the slot approximation is valid for the flow conditions in the annulus; but the boundary conditions are different, because the pipe is moving: y dp f y V c1 c2 dL V=0 V = -Vp y dp f y v c1 c 2μ dL μ When y = 0, v = - vp , When y = h, v = 0, At Hole Wall Substituting for c1 and c2: At Drillpipe Wall c v p h dp f h c1 v p 2μ dL μ v pμ h dp f c1 dL h dp f y v hy y v p 2μ dL h Velocity profile in the slot dp f y v hy y v p 2μ dL h h W q dq vdA vWdy h y v p W (1 )dy h v p Wh Wh dp f q 12μ dL Changing from SLOT to ANNULAR notation 2 A = Wh = π r r h r2 r1 v q ( r2 Substitute in: r1 ) v p Wh Wh dp f q 12μ dL 10