Comparison between double caliper,imaging logs,and array sonic log for determining the in-situ stress direction:A case study from the ultra-deep fractured tight sandstone reservoirs,the Cretaceous Bashijiqike Formation in Keshen8 region of Kuqa depress  

作　　者：Song Wang Gui-Wen Wang Dong Li Xing-Neng Wu Xu Chen Qi-Qi Wang Jun-Tao Cao Yi-Lin Zhang 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum Beijing,Beijing,102249,China [2]College of Geosciences,China University of Petroleum Beijing,Beijing,102249,China [3]Research Institute of Petroleum Exploration and Development,Tarim Oilfield Company,CNPC,Korla,841000,Xinjiang,China [4]Department of Geological Sciences,University of Texas at Austin,2275 Speedway Stop C9000,Austin,TX,78712,USA

出　　处：《Petroleum Science》2022年第6期2601-2617,共17页石油科学（英文版）

基　　金：financial support for this work comes from the Science Foundation of CUPB(No.2462017YJRC023);supported by the Exploration and Development Research Institute of Petro China Tarim Oilfield Branch Company

摘　　要：The tight sandstone in the Tarim Basin has the characteristics of large burial depth and development of nature fractures due to concentrated in-situ stress. Identifying the present-day in-situ stress orientation is important in hydrocarbon exploration and development, but also a key scientific question in understanding naturally fractured reservoirs. This paper presents a case study where we integrate various methods using wireline and image-log data, to identify present-day in-situ stress direction of ultra-deep fractured tight sandstone reservoirs, in the Kuqa depression. We discuss the formation mechanism of the elliptical borehole, compares the advantages and applicable conditions of the double caliper method,resistivity image logs and array sonic logs method. The well borehole diameter is measured orthogonally,then the ellipse is fitted, and the in-situ stress orientation is identified by the azimuth of the short-axis borehole, but it fails in the borehole expansion section, the fracture development section and the borehole collapse section. The micro-resistivity image logs method reveals the borehole breakouts azimuth, and also the strike of induced fractures, which are used to determine the orientation of in-situ stress. However, under water-based mud conditions, it’s hard to distinguish natural fractures from induced fractures by image logs. Under oil-based mud conditions, the induced fractures are difficult to identify due to the compromised image quality. As for the sonic log, shear waves will split when passing through an anisotropic formation, shear waves will split during propagation, and the azimuth of fast shear waves is consistent with the orientation of in-situ stress. However, it is usually affected by the anisotropy caused by the excessively fast rotation of the well log tools, so that the azimuth of fast shear wave cannot effectively reflect the orientation of the in-situ stress. Based on comprehensive assessment and comparison, in this paper we propose a method integrating various logging d

关 键 词：Fractured tight sandstone In-situ stress Orientation Well logs 

分 类 号：TE151[石油与天然气工程—油气勘探]