一种利用注水井关井压力曲线计算地层超压值的新方法

A new method for calculating formation overpressure value by using shut-in pressure curves of injection wells

PL油田是渤海最大的陆相多层砂岩油藏,断裂系统复杂,平面被分割成多个断块,含油井段长,单井钻遇油层厚度大,采用一套层系多层合注合采,历经十多年的注水开发,油田进入中高含水期,开发矛盾突出,防砂油井受微粒运移影响,造成纵向上各油组压力差异较大,超压和亏压程度不一,准确地判断地层超压情况对油田注水安全管理、新钻井和措施的实施非常重要。通过对油田大量注水井关井井口压力曲线(ISIP)形态分析,结合注水井压力变化微观机理,总结出三种超压地层的压力定量计算模式,创新地提出一套多层砂岩油藏超压层压力预测新方法。现场应用表明,该方法所预测的压力与随钻测压结果符合程度高达90%以上,说明该方法具有较强的适用性。

The PL Oilfield is the largest continental multilayer sandstone reservoir in the Bohai Sea with a complex fracture system,the plane is divided into multiple fault blocks,a long oil-bearing well section,a large thickness of oil layer drilled for a single well,using multilayer co-injection and co-production for a set of layers,after more than a decade of water injection and development,the oilfield has entered the medium-high water-cut stage,the contradiction of development is prominent,and sand control oil wells are affected by the particle migration.As a result,the pressure difference of each oil group in the vertical direction is large,and the degree of overpressure and pressure loss is different.It is essential to accurately judge the overpressure situation of the formation for the safe management of water injection,the implementation of new drilling wells,and measures.Based on the morphological analysis of the shut-in wellhead pressure curve(ISIP)of many water injection wells and the micro-mechanism of pressure change in water injection wells,three quantitative calculation models of pressure in overpressure formations are summarized.A new method for pressure prediction of overpressure formations in multi-layered sandstone reservoirs is innovatively put forward.The field application shows that the predicted pressure of this method is more than 90%consistent with the pressure measurement results while drilling,which indicates that this method has strong applicability.