页岩地层的破裂压力地震预测方法

在油气勘探开发过程中,地层破裂压力的有效预测对于评价井壁稳定性、设计安全钻井方案、压裂施工等方面有着重要作用。探讨了页岩地层的破裂压力地震预测方法:首先针对页岩地层具有强各向异性的特点,基于黄荣樽地层破裂压力预测模型,利用各向异性应力耦合因子,建立了更为全面的页岩各向异性破裂压力预测模型;其次根据岩石强度参数计算模型,利用反演得到的弹性参数和物性参数估算地层的抗压强度和抗张强度;采用基于波阻抗的地层压力预测方法获得地层的孔隙压力和上覆岩层压力;最后基于页岩各向异性破裂压力预测模型实现了页岩地层的破裂压力地震预测。将该方法应用于我国西部某页岩工区实际资料处理,得到了整个工区连续的地层破裂压力预测剖面,为该区面向靶区的钻井和水平井设计及压裂施工提供了可靠的参考依据。

In the exploration and development of oil and gas resources,the effective prediction of the pressure required for fracture formation plays an important role in evaluating wellbore stability,designing safe drilling schemes,and fracturing construction.This paper discusses a method for predicting the pressure required for fracture formation on the basis of seismic data.In this method,accounting for the strong anisotropy of the shale formation,and based on Huangrongzuns model for predicting the pressure of fracture formation,an anisotropic stress coupling factor is firstly introduced to establish an anisotropic fracture pressure prediction model for shale formation.Subsequently,based on a numerical model for calculating rock strength parameters,the elastic and physical parameters obtained by inversion are used to estimate the compressive and tensile strengths of the formation.Meanwhile,pore pressures and overburden pressures in the formation are obtained by the prediction method of formation pressure based on wave impedance.Finally,based on the shale anisotropic fracture pressure prediction model,the pressure for fracture formation in the shale formation can be predicted.The application to a real case showed that the proposed method can provide a continuous pressure profile in the whole working area,thereby supplying a reliable basis and useful advice for drilling and horizontal well design,and thus for hydraulic fracturing in the target area.

国家科技重大专项(2017ZX05036005-010)资助。