特低渗透油田高含水期提压增注技术研究——以鄯善油田为例

The technical study of the increasing pressure and water injection well stimulation in Shanshan Oilfield

鄯善油田是埋藏深度3 018 m的特低渗透油田,主要产层为侏罗系三间房组砂岩,平均有效孔隙度12.8%,空气渗透率6.2×10-3μm2,具有非达西渗流特征。高含水期启动压力上升,难以形成有效压力驱替场,储层吸水及供液能力下降,层间矛盾加剧。应用泊松比法和水力压裂经验法研究破裂压力界限,从超破压注水和形成有效驱替压力梯度两方面论证了提压下限;通过理论计算、试井分析及现场试验确定了井层合理注水强度,确定了建立有效驱替压力梯度的合理压力。提压后,吸水剖面得到改善,对应采油井大面积见效。这为同类型油田开发后期注水结构调整提供依据,补充完善了特低渗透油田注水开发配套技术。

The burial depth in Shanshan extra-low permeabile Oilfield was 3 000 meters, Jurassic Sanjianfang reservoir is the main oil pay and the Physical properties of the reservoir is not good and has the character of non-Darcy flow. For raised the injection threshold pressure in the high water-cut stage, it is difficult to form the effective displacement field, furthermore the capacity of supply fluid is coming down in the reservoir and the difference among the reservoir beds is the experiential expressions of the hydraulic fracturing the becoming serious. Using the Poisson＇s ratio and breakdown pressure radius was studied and the least of increase pressure was demonstrated through the way of the abnormal fracturing pressure and the effective pressure gradient; confirmed the optimal water intake per unit thickness and formed the logical pressure that can make the effective displacement pressure gradient through the theoretic calculation, the well test analysis and field test. After increasing pressure, the water intake per unit thickness was become better and the fluid of the oil well was enhanced in great degree . It can provide reference for the same oil field in the late development stage and perfect the matched techniques of the water injection stage in the extra-low permeability oil field .