声波远场三维成像测井技术及应用

Acoustic far-field three-dimensional imaging logging technology and its application

西北地区深层油气多富集在缝洞储层,大缝洞精细评价和小缝洞有效探测是缝洞型碳酸岩油气藏勘探亟待解决的关键问题。声反射法可对井周地层成像,传统单极反射纵波成像方法可对井周约20 m范围内的异常体成像。偶极横波远探测方法具有发射频率低、探测深度大的显著优势,但具有180◦方位不确定性。该研究在前期研制的远场偶极横波远探测测井仪基础上,采用该仪器结构和非对称组合接收的方位区分方法分别对有无反射界面的地层模型开展有限差分模拟。对裂缝、溶洞、孔洞三种典型缝洞地质模型进行正反演,获得了典型缝洞模型的远探测响应特征和成像结果并升级了远探测处理解释软件,应用于西北地区某井。通过对缝洞型地质异常体的远探测测井、常规测井、电成像测井、地震资料等综合分析,形成近井到远井地质异常体形态及发育情况的精细刻画,实现多尺度、全方位和高精度的缝洞体描述与解释。

Oil and gas in the deep formations of northwest areas are mostly enriched in the fracture-cave reservoirs.Fine evaluation of large-scale fracture-cave and effective investigation of small-scale fracture-cave are the key issues to be tackled in the exploration of fracture-cave type carbonate reservoirs.Acoustic re-flection method is able to image the formation around the well.Traditional monopole P wave reflection method enable near-borehole structure imaging within about 20 meters.Dipole S wave remote detection has the re-markable advantages of low emission frequency and larger investigation depth,but it has 180 degrees azimuthal ambiguity.This study is based on previously developed farfield dipole S wave remote detection tool.The instrumental structure and azimuthal differentiation method of asymmetric combination reception is adopted and thefinite-difference simulation of the formation model with and without reflective interface is carried out.Forward modeling and inversion are implemented on three representative geological models such as fractures,caves,and holes.Responsive characteristics and imaging results are obtained for representative fracture-cave formations and remote detection processing and interpretation software is updated.These are applied on a well in the northwestern area.Through the comprehensive analysis of remote logging,conventional logging,electri-cal imaging logging and seismic data of the fracture-cave geological anomalies,afine image of the morphology and development of the geological anomalies from the near wellbore to the far end is obtained.Multi-scale,all-round and high-precision description and interpretation of fracture-cave reservoir is achieved.