钻井液浸泡时间对返排效果的影响模拟研究

EXPERIMENTAL STUDY ON INFLUENCE OF SOAKING TIME IN DRILL-IN FLUIDS FILTRATE ON RETURN EFFECTIVENESS OF RESERVOIRS

室内钻井液动态损害评价实验往往在较短时间内完成,与现场实际钻井过程不符。利用高温高压动态损害评价仪,模拟现场实际钻井过程,将被钻井液损害后的岩芯浸泡在钻井液滤液中一定时间后取出返排,评价不同浸泡时间对返排效果的影响程度。实验结果表明:随着钻井液滤液浸泡时间的增加,油基钻井液体系的返排恢复率变化不大,水基聚合醇体系的返排恢复率有下降的趋势;短时间浸泡时变化不大,长时间浸泡后返排效果明显变差;无固相体系的总体趋势是增加的。钻井液滤液浸泡时间对返排效果的影响主要与钻井液性质、储层特征、储层损害机理等因素有关。

The dynamic damage experiment of drill-in fluids in the laboratory is often completed in a short time,which does not correspond with actual drilling process.The article utilizes HTHP dynamic evaluation instrumentto simulate the actual drilling process.We soak the core which is damaged by drill-in fluids into drill-in fluidfiltrate for certain time,and bring it out to evaluate the affecting degree of different soaking time on reservoir returneffectiveness.The experimental results show that,with the increasing of soaking time in the dill-in fluids filtrate,thereturn effectiveness of oil-based drill-in fluid have few variation,and the return effectiveness of polymeric alcoholdrill-in fluid trend to decline;there is few variation in the process of soaking in a short time.On the contrast,thereturn effectiveness tends to decrease after a long time,and clay-free drill-in fluid trend to decrease.The influenceof soaking time in drill-in fluids filtrate on return effectiveness is relative to the characteristic of drill-in fluids,reservoir characteristics,reservoir damage mechanisms and etc.