Title

Sweet-spot prediction and aided design for drilling engineering: Application to deep shale gas reservoirs in the Sichuan Basin

单位

(1.中国石油化工股份有限公司西南油气分公司,四川成都610041;2.电子科技大学资源与环境学院,四川成都611731;3.成都理工大学“油气藏地质及开发工程”国家重点实验室,四川成都610059;4.成都理工大学“地球探测与信息技术”教育部重点实验室,四川成都610059;5.中国石油化工股份有限公司西南油气分公司勘探开发研究院,四川成都610041)

Organization

(1.Southwest Oil and Gas Branch Company,SINOPEC,Chengdu 610041,China;2.School of Resources and Environment,University of Electronic Science and Technology of China,Chengdu 611731,China;3.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of Technology,Chengdu 610059,China;4.Key Lab of Earth Exploration & Information Techniques of Ministry of Education,Chengdu University of Technology,Chengdu 610059,China;5.Exploration＆ Production Ｒesearch Institute,SINOPEC Southwest Oil ＆ Gas Company,Chengdu 610041,China)

摘要

四川盆地优质页岩储层受埋藏深、厚度薄、致密化程度高等复杂条件的制约,页岩气勘探开发难度大。经过近8年的勘探开发研究与实践,形成了四川盆地深层页岩气“甜点”预测与钻井工程辅助设计技术,具体如下:①综合利用大偏移距、宽方位、高覆盖次数、小面元的三维地震资料和地质、测井、岩石物理等信息,在有利沉积相带分析和构造解释的基础上,采用岩石物理敏感参数分析、弹性参数反演和有机碳含量(TOC)反演等方法,获得页岩储层有利沉积相带、构造、埋深、岩性、物性、脆性、生烃能力、含气量、裂缝、孔隙流体压力和地应力差异等“甜点”要素,实现地质与工程“甜点”综合评价与逐级分类;②将Ⅰ类和Ⅱ类“甜点”列为重点开发目标,利用地质、地球物理、工程一体化水平井轨道设计、跟踪与动态调整及压裂数值模拟等方法,实现深层页岩气钻井工程地球物理辅助设计与现场支撑。该技术在威远、荣县、永川、井研—犍为、丁山、赤水等页岩气探区的勘探开发中发挥了重要作用,实现了四川盆地深层页岩气的高效勘探与商业化开发。

Abstract

The exploration and development of deep shale gas in the Sichuan Basin is very difficult because of the complex conditions in which high-quality shale reservoirs occur.In fact,they are usually found in thin and deeply-buried layers with a high degree of densification.Summarizing approximately eight years of exploration and practice,this paper illustrates a method for sweet-spot prediction and aided design for drilling engineering.The first step of the method consists of obtaining relevant information for sweet-spot prediction by performing a sensitivity analysis of petrophysical parameters together with the inversion of elastic parameters and total organic carbon content profiles.In addition,structural interpretations using multiple large-offset,wide-azimuth,small-bin three-dimensional seismic data need to be performed in addition to extensive geological,logging and petrophysical characterization.Such a comprehensive geological and engineering investigation can greatly help identify favorable sedimentary facies belt,structure,burial depth,lithology,porosity,brittleness,hydrocarbon generation ability,gas content,fracture networks,pore fluid pressures,and geostress differences in deep shale reservoirs.The so-identified sweet spots are then grouped into classes,with those falling into classes I and II being regarded as the key development objectives.The next step entails the implementation of a number of engineering methods to support drilling operations in the field,namely:horizontal well trajectory design,tracking and dynamic adjustment,and numerical simulation of fracturing.This aided design has played a key role in Weiyuan,Rongxian,Yongchuan,Jingyan—Qianwei,Dingshan,Chishui,and other deep shale gas exploration areas,thereby promoting the efficient seismic exploration and commercial development of deep shale gas in the Sichuan Basin.

关键词：

深层页岩气; 地质与工程“ 甜点” 地震; 岩石物理; 测井; 钻井工程; 辅助设计;

Keywords:

deep shal gas;; geological and engineering “Sweet spot”;; seismic;; rock physics;; well logging;; drilling engineering;; aided design;

基金项目

国家自然科学基金面上项目“基于各向异性介质弹性参数的页岩TOC及脆性预测方法”(41574099)和四川省科技创新人才项目“页岩储层智能化含气性预测方法”(2020JDRC0013)共同资助。

DOI

10.3969/j.issn.1000-1441.2021.03.014