欠平衡钻井随钻预测储层压力的理论与实用方法研究

Theory and Practical Method on Forecasting Fluid Pressure in Reservoirs While Under-balanced Drilling

欠平衡钻井过程中,真实地了解所钻地层的多种信息对于安全钻进、钻井液密度控制、井口回压控制及复杂事故处理都非常重要,但凭借钻前邻井资料预测和随钻录井分析获得的储层压力往往与实际相差较大,造成了欠平衡压力控制的误差和滞后。为求得较准确的储层压力,在原有压力恢复试井理论基础上,推导出了欠平衡钻井随钻储层压力恢复试井数学模型,并提出了相应的简化的实用方法随钻储层压力恢复试井法。同时,结合2口井的欠平衡钻井实例数据,利用该方法进行了分析,结果与实际储层压力的误差较小,从而验证了该方法的可行性。

It is important for drilling security, controlling density of drilling fluid and choke pressure, and dealing with complex accidents that knowing well multi-information of drilled formations while UBD. In fact, the formation pressure in UBD was only acquired by right of the datum of offset wells before drilling and analyze of well loging during drilling, but these outputs always differ from the reality, and result in error and lag of the pressure controlling in UBD. In order to predict fluid pressure in reservoirs more accurately, this paper deduces a novel mathematical model based on conventional well test, and presents accordingly simplified practical methods named fluid pressure recover in reservoirs. In addition, the new method is applied to 2 wells. The results of the formation pressure computed by the new method are compared with the field true data, and there is little differences between them. It is shown that the new method is reliable.