| The characteristics of the desert margin reservoir in Tarim basin,such as deep burial,complex and changeable lithology,and great variation of formation pressure system,lead to the emergence of construction:?.During the directional construction,the friction and torque are large,the supporting pressure is serious,and the well trajectory is difficult to control;?.In the oblique section affected by bending stress,it is easy to cause fatigue damage of the drill;?.The annular air pressure is large,and the water conservancy parameters are difficult to optimize at the maximum;?.The borehole wall is unstable,the mudstone is easy to hydrate,and the performance of the drilling fluid is unstable.The rapid down-conversion of the bottom hole pressure and the flooding of the main oil layer resulted in short life and rapid decline in production,which seriously affected the development benefit of the old well.The side-drilling horizontal well of the desert edge of the Tarim Oilfield is an effective means for raising oil and gas production in the old block.The reason is that it is relatively easy to drill new wells and adjust wells,which can greatly save development costs and achieve good development results.Aiming at the problems of long open hole section,difficult trajectory design and control,and complicated geological conditions of high temperature and high pressure in the desert edge area of Tarim Basin,this paper has carried out the research on deep sidetracking horizontal well technology in this area.The technology of sidetracking horizontal wells is formed which is suitable for deep well depth and complex geological conditions of high ground temperature in this area.Based on the 3D rigid rod friction torque calculation model of drill string,the friction torque distribution of drill string under different hole trajectory conditions is compared and analyzed,and the hole trajectory of sidetracking horizontal well is selected.By comparing and analyzing the cumulative friction and torque of different drill string structures under various working conditions,the optimum drilling tool combination suitable for ultra-deep sidetracking horizontal wells is determined;Aiming at the characteristics of small annulus clearance,eccentric drilling string and large annulus friction during the casing window sidetracking in small bore hole,the hydraulic parameters suitable for slim hole are optimized,and the performance of the existing drilling fluid system is evaluated in laboratory according to the geological characteristics and the exploitation situation in the old area,and the formulation of the anti-high temperature and high lubricating drilling fluid system is improved.The results show that the barefoot laterally drilling horizontal well at the edge of Tarim Desert can choose the 20°/30m?25°/30m build-up rate,according to the vertical depth of the target area and the selected build-up rate,side tracking point is determined by the single arc slanting section,and the side tracking point depth is larger than the ?177.8mm casing shoe depth.When the horizontal displacement and vertical depth are the same and the borehole curvature is 20°/30m?25°/30m,the friction and torque change little;the drill string will be buckling in the drilling process under the ultra deep casing sidetracking,and the contact force between the drill string and the wellbore becomes larger,and the axial friction and circumferential friction are increased;The frictional torque of drill string is closer to the real value considering the buckling of drill string,and the calculation of pump pressure is in good agreement with the measured pump pressure when considering the joint.The difference of less than 1MPa,the error is less than 5%,in the case of nominal pump pressure unchanged,the higher the displacement,the shorter the limit extension length of the horizontal section;When the displacement is constant and the pump pressure is larger,the limit extension length is larger;Through the optimization of the treatment agent,the formula for the high temperature-lubricated drilling fluid is obtained:4%bentonite+0.3%KPAM+0.2%NPAM+1.5%SMP-1+1.5%SMP-2+1?2%SPNH+2%YK-H+ crude oil+1%emulsifier+1?2%lubricant+2%QS-2.By optimizing the design of ultra-deep sidetracking horizontal wells at the desert edge of the Tarim Basin,we will vigorously promote the construction of small coupling drill pipes in the ultra-deep sidetracking horizontal wells in the desert edge of the Tarim Basin.In 2017,the ultra-deep sidetracking horizontal wells in the desert edge of the Tarim Basin will be drilled.Compared with previous years,there has been a significant improvement. |
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