深水高温高压井钻采过程中密闭环空压力预测和套管柱力学研究

With the growth of energy demand and the improvement of deepwater oil and gas exploration and development technology, china pays more and more attention to the deepwater oil and gas drilling and development. But at present, a lot of deepwater wells are encountered the phenomenon of annular pressure buildup, tubular failure and cement leak. These problems seriously restrict the deepwater oil and gas exploration and development in China. This project focuses on the deepwater high temperature and high pressure wells, studies on the temperature distribution rule, sealed annulus pressure prediction, deepwater tubular mechanical behavior and prediction method of cement strength using the theoretical analysis and numerical simulation methods. This project will bring scientific basis and technical measures for solving the encountered problems in the deepwater oil and gas exploration and development, such as annular pressure buildup, tubular failure and so on. Through the studies, the temperature and pressure distribution rules will be gotten, the prediction model of sealed annulus pressure will be built up, and the tubular and cement failure mechanism and mechanical behavior under complex load will be analyzed. In the end, the prediction method of sealed annulus pressure and optimization theories of casing design which are suitable for deepwater environment will be built.

随着我国能源需求的增长以及深水油气勘探开发技术的不断进步，人们越来越重视深水油气资源的钻探与开发。但是目前，我国深水油气资源开发过程中面临着一系列的问题，例如环空带压、管柱变形破坏、水泥环失效等，这些问题严重制约了我国深水油气资源勘探开发的步伐。本项目主要针对我国深水高温高压井的特点以及钻完井过程中遇到的问题，综合运用理论分析和数值模拟的方法，着重研究深水井井筒温度动态分布规律、深水井密闭环空压力预测、深水井复杂载荷下的套管和水泥环受力，为解决深水油气资源勘探开发中遇到的环空带压、管柱破坏等难题提供科学依据和技术对策。通过本项研究，得到深水井井筒温度和压力剖面，建立深水井密闭环空压力预测模型，分析复杂载荷条件下深水管柱的力学行为，最终形成一套适合我国深水井的环空压力预测以及管柱优化设计理论方法。

随着我国能源需求的增长以及深水油气勘探开发技术的不断进步，人们越来越重视深水油气资源的钻探与开发。但是目前，我国深水油气资源开发过程中面临着一系列的问题，例如环空带压、管柱变形破坏等，这些问题严重制约了我国深水油气资源勘探开发的步伐。本项目主要针对我国深水的特点以及钻完井过程中遇到的问题，综合运用理论分析和数值模拟的方法，着重研究深水井井筒温度分布规律、深水井密闭环空压力预测、深水井管柱受力，为解决深水油气资源勘探开发中遇到的环空带压、管柱破坏等难题提供科学依据和技术对策。基于弹性力学，建立了套管-水泥环-地层系统环空圈闭压力计算方法，分别考虑了套管自由段和封固段变形，得到环空体积变化对圈闭压力影响；结合环空流体热物性参数测试值建立环空圈闭压力计算方法；采用牛顿迭代求解方法进行计算，得到井筒不同环空圈闭压力值。同时对环空圈闭压力计算模型进行敏感因素分析，分析了温度、钻井液热物性参数、套管参数、水泥环和地层参数、压力释放等都对圈闭压力的影响。采用Visual Basic语言，开发了一套环空圈闭压力计算软件，该软件通过导入井筒温度剖面，默认计算或软件界面输入流体热物性参数，根据建立的环空圈闭压力模型，从而计算各个环空圈闭压力值。根据圈闭压力的影响因素，将环空圈闭压力防治技术按照防治原理分为压力释放、增加结构强度、增加环空流体可压缩性和隔热四种。通过研究得到的成果，为今后深水高温高压井环空带压的预测及防治技术提供了科学依据。