凝析气藏压裂测试新技术

NEW FRACTURING AND TESTING TECHNIQUES FOR THE GAS CONDENSATE RESERVOIRS

为解决川西坳陷GM构造上的沙溪庙组气藏储层破裂压力异常高,施工压力高,排液过程中压力下降快、产凝析油、自然返排率较低等问题,采用酸预处理降低了破裂压力和施工压力,采用优化压裂液配方避免了压裂液乳化和黏土膨胀。通过PVT实验确定露点压力,并创新性提出了控压返排措施,压后返排率由前期的平均35.5%提高至60.1%,施工成功率从75%提高至100%,压后天然气测试产量从措施前平均1.69×10~4 m^3/d提高至3.87×10~4 m^3/d。控压返排制度结合防膨防乳化压裂液技术大幅提高了凝析气藏的压后返排率和压后效果。

In order to solve the following problems of Shaximiao-Formation gas reservoirs in West-Sichuan GM De- pression Structure： abnormally high fracture pressure, high operation pressure, rapid pressure drop in the process of the liquid discharge, oil eondensate production, rather lower natural flowback rate and so on, with the help of the acid pretreatment, the breakdown and construction pressures are reduced ; the optimization of the fracturing flu- id formulation avoids the fracturing fluid emulsion and clay swelling; by means of the PVT experiments, the dew point pressure is determined, and moreover the innovative proposed measures are presented to control the pressure and flowback, the average flowbaek rate after the fracturing increases from 35.5% to 60. 1%, the success rate of the eonstruction improves from 75% to 100%, and furthermore the gas production test has increased from 1.69 ×104 m3/d averagely before the simulation to 3.87 × 104 m3/d after the fracturing. In a word, the measure combined with the fracturing technique of preventing the fraeturing fluid emulsion and clay swelling has greatly enhanced the post-frac flowback rate and effects.