川西致密砂岩气藏现今地应力剖面评价软件编制

【摘要】： The research of earth stress has been widely used in many petroleum engineering areas, and it has become a necessary basic data in which the oil and gas reservoir engineering, the oil and gas exploration, the drilling and completion wells and the program design of oil and gas production engineering, and it is important to various aspects which the evaluation of wellbore stability during drilling well, the prediction of burst pressure, and the prediction and prevention of damaged oil and water well casing. Furthermore, with the rapid increase of gas requirements, many countries have attached importance to the exploration and development in compact sandstone gas reservoir. It was base on the research of earth stress that the wellbore instability, hydraulic fracture and other technology often happened in compact sandstone gas reservoir. In this thesis, we take the Xujiahe Formation of Xinchang area in Western Sichuan depression as an example. According to theories and methods in many kinds of subjects as petroleum geology, structural geology, geophysical well logging, reservoir geology, rock mechanics, drilling engineering and so on, begin with an analysis on character of rock mechanics, we carry out many researches such as the rock mechanics trial, interpretation of earth stress, establishment of three major stress, prediction of fracture pressure and collapse pressure. However, researches on the earth stress software design are scare in higher education institutions in China. Therefore, according the theories above all, we developed the earth stress interpretation visual windows software on Visual C++6.0 platform. This software not only integrated a large number of achievements of the former research, but also provided different mathematical methods for users to create new model for different实曲线,发现研究区深层须家河组存在异常高压,从而得到正常压实趋势线,这为利用各种方法计算地层孔隙压力提供了可靠的基础,并反演获得压实指数;利用伊顿经验公式法计算地层孔隙压力,然后运用BP神经网络对研究区各单井地层孔隙压力进行预测,并与伊顿经验公式法计算地层孔隙压力进行对比分析,认为两种方法计算精度都较高,但BP神经网络预测结果优于伊顿经验公式法,有较好的应用前景;在获得各项参数的基础上,系统研究了研究区地应力大小计算方法,并通过对声发射法、压裂法以及国内前人在测井估算法上的研究成果上进行深入学习,选择ADS法计算研究区各单井地应力,用分层累加上覆岩层重量计算代替对密度函数进行积分从而获得垂向地应力值,并得到各单井应力计算剖面。最终通过计算结果确定地层坍塌压力和破裂压力大小,分析获得适合研究区的安全泥浆密度窗口。 本研究基于Visual C++6.0为平台利用MFC进行可视化程序设计,开发了一套评价方法较全面的地应力剖面评价软件。该软件由参数求取模块,地应力研究模块和单井剖面建立模块组成。参数求取模块实现纵横波提取,其集成了Eberhart-Philips(1989),甘利灯(1990),李庆忠(1992),周文(2009)等建立的较成熟的八个经验公式,并且提供建立适合研究区模型建立的软件功能;常用测井方法解释的泥质含量计算功能;岩石弹性参数即泊松比、杨氏模量、剪切模量、体积模量、地层压缩系数、骨架压缩系数的计算;软件通过继承Miller和Deere、McNally (1987)、周文(1998)、Horsrud (2001)、王渊等(2005)等研究的计算模型提供岩石强度参数即抗张强度、抗压强度、抗剪强度计算功能,并通过软件提供的数学模型建立了适合该区域的强度参数计算模型,并集成动静校正转换功能模块。软件集成常用的伊顿经验公式法实现地层孔隙压力计算模块、地应力计算模块、坍塌压力预测模块和破裂压力预测模块,该软件提供8个常用地应力计算模型,2个坍塌压力计算模型和13个破裂压力计算模型。最后,单井剖面通过与专业曲线绘制软件接口连接实现单井剖面的绘制,从而最终获得一套系统、全面的地应力评价软件。