基于多源信息的实时井筒压力预测及井下状况识别方法

With the continuous development of oil and gas exploration in deep sea and stratum, the formation conditions and downhole environment are more and more complex. How to predict the downhole condition in real time according to the gradually diversified and sophisticated monitoring information has become one of the key issues in the field of drilling engineering. The project presents a research method of real-time prediction of wellbore pressure and downhole condition using multi-source information such as wellhead overflow characteristics and other related drilling parameters. By studying the key scientific problems of the response rules and identification method of the wellhead overflow characteristics and other related drilling parameters to the downhole fluid invasion conditions, and based on the combination of theoretical analysis, numerical simulation and experiment, the wellbore pressure and ECD real-time accurate calculation method will be established. Meanwhile, the variation law of wellbore pressure under different conditions of wellhead overflow characteristics and downhole fluid invasion will be proved. It aims to reveal the response rules and differences between the wellhead overflow characteristics and other related drilling parameters and the complex downhole conditions such as gas kick, overflow, leak and borehole ballooning and breathing. At the same time, the method of identifying formation permeability by using multi-source information such as stop-drilling test data will be proposed. Finally, a set of real-time wellbore pressure prediction and downhole condition identification method based on multi-source information will be provided, which provides the theoretical basis for the effective control of well bore pressure and the aversion of downhole engineering risk.

随着油气勘探开发向深海深地领域的不断深入，钻井施工过程中所面临的地层条件和井下环境越来越复杂，如何依据逐步多元化和精细化的监测信息实时预测井下状况成为钻井工程领域普遍关注和重点研究的关键问题之一。该项目提出了一种利用井口溢流特征及相关钻井参数等多源信息实时预测井筒压力和井下状况的研究思路。通过重点研究井口溢流特征及相关钻井参数与井下流体侵入状况的响应规律及其识别方法这一关键科学问题，采用理论、数模和实验相结合的方法，建立井筒压力及ECD实时精确计算方法，探明不同井口溢流特征及井下流体侵入条件下井筒压力的变化规律，揭示井口溢流特征及相关钻井参数与气侵、溢流、井漏和呼吸效应等井下复杂情况的响应规律及差异特征，同时提出利用停钻测试数据等多源信息识别地层渗透特征的方法，形成一套基于多源信息的实时井筒压力预测及井下状况识别方法，为深井复杂地层的井筒压力高效控制与井下工程风险规避提供理论依据。

本项目针对深海、深地钻井中井口溢流特征及相关钻井参数与井下流体侵入状况的响应规律及其识别方法这一关键科学问题，采用理论、数模和实验相结合的方法，探明不同井口溢流特征及井下流体侵入条件下井筒压力的变化规律，揭示井口溢流特征及相关钻井参数与气侵、溢流、井漏和呼吸效应等井下复杂情况的响应规律及差异特征，形成一套基于多源信息的实时井筒压力预测及井下状况识别方法。.通过开展上述研究获得的主要结论如下：.1）针对深水深地钻井工况，综合考虑海水温度场（地温梯度）、井筒换热、气侵、流变模式、钻杆偏心、转速、钻杆接头、起下钻波动压力等因素的影响，建立了钻井井筒压力及ECD的精确计算模型及修正方法，并利用我国南海陵水某深水井的三个井段进行了对比分析，模型计算ECD与PWD实测值的相对误差均小于1%。.2）引入BP-Dematel模型建立了钻井过程中井下复杂情况响应因素分析方法。通过BP神经网络计算多源信息（钻井、录井参数）与井下工况（气侵、溢流、井漏、卡钻等）之间的权值，基于复杂网络理论对Dematel算法进行改进。结合四川盆地某气田的实例分析，探明了随钻测井、录井和钻井参数与井下复杂情况之间的响应关系，模型分析结果与工程实际基本吻合。.3）基于流固耦合理论和相场方法，建立了模拟井筒呼吸效应的压力场-应力场-相场耦合的数学模型。分析了不同井筒压力变化引起的裂缝起裂、扩展和闭合过程中，流体压力和漏失体积随时间的变化规律，探明了引起井筒呼吸效应的井筒压力波动的上下限，为现场判别井筒呼吸效应提供了理论和判别依据。.4）形成了一套基于多源信息的实时井筒压力精确预测及井下状况识别方法，该方法在精确计算井筒压力及ECD的基础上，通过建立钻井、录井、随钻测井等多源化监测数据与井下复杂情况之间的响应关系，以及井筒呼吸效应的判别方法，提高了深水深层钻井井下状况的识别精度和可靠度，为实现深井复杂地层的井筒压力高效控制与井下工程风险规避提供了理论基础和技术支撑。

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