酸损伤射孔井储集层破裂压力预测模型

A model for predicting reservoir fracturing pressure of perforated wells after acid damage

酸损伤是解决深层、致密、低渗透砂岩油气藏储集层改造(压裂或者酸化压裂等)过程中高破裂压力难题的有效措施之一。结合损伤力学、断裂力学和有限元基本理论,建立了酸损伤射孔井储集层破裂压力的定量预测模型,模型综合考虑了岩石矿物组成、酸类型、酸用量、温度等对破裂压力的影响。利用所建模型对川西酸损伤射孔井DY1井储集层的损伤变量和破裂压力进行了定量预测,结果表明酸液浓度越高,岩石损伤变量越大,岩石强度降低幅度越大,越有助于降低破裂压力。使用优选出的主体酸液15%HCl+3%HF进行酸损伤施工,使破裂压力降低了6.5MPa,保证了后续网络裂缝酸化施工的顺利实施。矿场结果与理论模型预测结果吻合程度高,验证了模型的可靠性。

Acid damage is an effective technology to solve the problem of high fracturing pressure for the deep,tight,low-permeability sandstone reservoirs during fracturing or acid fracturing.A model for quantitatively predicting reservoir fracturing pressure of perforated wells with acid damage was established combining with damage mechanics,fracture mechanics and the finite element theory.The model considered the effects of rock mineral composition,acid type,acid amount and temperature on fracturing pressure.The model was used to quantitatively predict the damage variable and fracturing pressure of the acid damaged formation in the Well DY1 in west Sichuan.The results showed that the higher the acid concentration,the higher the rock damage variable and the larger the rock strength reduction,and it will be more favorable for reducing fracturing pressure.The optimal 15%HCl＋3%HF acid was applied and the fracture pressure was reduced by 6.5 MPa successfully,which ensured the following ＂fracture network＂ acidation implementation.Field application results agreed with the prediction results,which verified the reliability of the model.