泥浆侵入地层感应测井响应的有限元计算  

FEM Modelling of Induction Responses to Mud—filtrate Invaded Formation

作　　者：刘振华[1] 胡启 张建华[1] 

机构地区：[1]西安石油学院

出　　处：《测井技术》1993年第6期442-446,共5页Well Logging Technology

基　　金：国家自然科学基金; 中国石油天然气总公司科技发展局

摘　　要：淡水泥浆滤液侵入孔隙性和渗透性地层时,其侵入过程远非传统的阶跃模型所描述的那样呈阶梯状突变,而是沿径向呈复杂的分布,同时还是一个与时间有关的动态过程。因此,研究侵入条件下感应测井的响应,必须考虑时间因素。作者利用多相渗流理论研究了侵入条件下地层流体参数和电性参数的分布特征,根据电磁场理论,建立了求解感应测井响应的有限元计算模型。结果表明,在动态侵入条件下,感应测井电阻率响应不仅与地层参数、流体性质有关,而且还与测井时间有关,使得深、中感应测井响应之差(R_(ID)—R_(IM))随侵入时间的增加呈现正、负交替的变化。与几何因子理论计算的结果相比,由有限元方法得到的感应测井响应随时间变化的幅度要小,并且(R_(ID)—R_(IM))的峰值对应的时间以及 R_(ID)和 R_(IM)的交会时间迟于几何因子理论的结果。When fresh water mud-filtrate invades porous and permeable formation,the invaded zone doesn't have a perfect piston-like profile as described in the″step profile″model,but has a com- plex radial distribution.The invasion process is a dynamic one which relates to the invaded time. Therefore,the effect of the invaded time on induction response must be considered.In this paper, distribution properties of formation fluid and electric parameters were studied in light of the theory of multi-phase fluid flow in porous media while the invasion occurred.The FEM modelling was made to solve induction responses according to the theory of electromagnetic field.The result shows that induction response relates to not only the properties of formation and fluid,but also the time when the well logging was performed.The difference between deep and medium induction responses(R_(ID)-R_(IM))varies from positive to negative alternatively with the increase of invasion time.Variations of induction responses with invaded time obtained by FEM are much less than that obtained from the computation in light of the theory of geometric factor.And the time corre- sponding to the peak value of the difference of R_(ID) and R_(IM)(R_(ID)-R_(IM))as well as the time at the cross point of R_(ID) and R_(IM) are later than the results from the theory of geometric factor.

关 键 词：电测井 计算 泥浆 地层 感应测井 

分 类 号：P631.811[天文地球—地质矿产勘探]