海洋深水钻井

?随着世界各国对能源需求的增加及陆上和海水浅水区发现难度的增大，深水油气勘探不断升温。

在深水水平井钻井过程中井控技术是深水油气开发的核心技术之一，环空多相流流动规律研究则是井控理论的重要组成部分。

由于深水的存在使得环空多相流的流动特征与陆上相比更加复杂。

因此，进行深水水平井井控技术研究，对深水安全钻井具有重要意义。

????本文以传热学和热力学理论为基础，推导了深水钻井及压井过程温度分布模型，计算了深水井井筒温度场随井深和时间的变化关系；以气体分别在水中和油中的溶解度模型为基础，建立了气体在钻井液中的溶解度计算模型，计算得到了不同温度、压力下气体在钻井液中的溶解度。

在深入研究国内外多相流理论基础上，基于质量守恒、动量守恒原理，建立了适合于深水水平井的地层——井筒——隔水管——地面系统压力传递数学模型，并给出相应的边界条件，应用有限差分方法进行了数值求解，编制了模拟深水水平井溢流发生及压井分析的软件，分析了出气量、钻井液排量和钻井液体系等对环空压力和持液率等参数的影响规律。

考虑井底压差对地层渗流过程的影响，模拟计算了溢流发生过程中井底压力随时间变化关系，对影响溢流的敏感性因素及其影响规律进行了模拟分析。

对比分析了深水与陆上水平井压井过程，分析了节流管线长度、节流管内径和水平段长度对压井过程中立管压力和节流阀压力的影响，得到了立管压力和节流阀压力随时间的变化关系。

????模拟计算表明：出气量、排量和钻井液体系等因素对环空流动参数影响较大。

深水水平井的水平段越长井底压力降低越快，当气体快到井口时，井底压力几乎呈直线下降。

通过模拟深水水平井压井过程发现：节流管线越长，节流管内径越小，节流阀压力越大；水平段长度对深水水平井压井过程中立管压力和节流阀压力影响不大。

????本文研究成果可用于预测深水水平井环空循环温度场分布，气体在钻井液中的溶解度，结合上述模型可得到深水水平井溢流发展过程，为制定合理的压井施工措施提供理论支持。

? Deep-water petroleum exploration has been given more and more focus with the increasing demand for energy all over the world and the difficulties for finding oil and gas in land and shallow water. The well control is one of the core technologies during the deep drilling operations and multiphase flowing in annuals is an important part of well control theory. The characteristics of multiphase flowing in annuals become more complicate than the land because of the deep water. Therefore, take research on well control of horizontal well in deep water has great significance for the safety of deep-water drilling.
????Based on the heat and thermodynamics theory, the temperature distribution model for drilling and well control in deep water is derived and the temperature changing results with the depth of well and the change of time is calculated. The solubility of gas in the drilling fluid model is established according to the solubility of gas in oil and water model. Then the solubility of gas under different temperature and pressure conditions is calculated. Based on investigate multiphase flowing theory of aboard and home, and mass and momentum conservation, a model for formation -wellbore- riser -ground pressure transmission system of deep water horizontal well is established. With the boundary condition and application of finite difference numerical method, a kind of software was programmed to simulate overflow of horizontal well in deep water and doing the well control analysis. The effect of gas production, displacement of drilling fluid and drilling fluid system on annual pressure and liquid hold ratio is analyzed. By considering the effect of bottom-hole pressure difference on seepage process, the pressure change with time during overflow is simulated. The sensitivity factors and influence laws of overflow is analyzed. With the comparison
study of the horizontal well on deepwater and land, analysis the effect of the length and inner radius of throttle pipeline and horizontal length of well on the stand pipe pressure and throttle pressure during well control, the stand pipe pressure and throttle pressure changes over time is obtained.
????The calculation results showed that subsystem, displacement and drilling fluid system have grate effect on annual flow parameters. The longer of horizontal length of well in deepwater, the faster of pressure dropdown. The pressure drops as almost a straight-line when gas nearly gets to the wellhead. According to the well control of horizontal well in deepwater simulation, the longer throttle pipeline and the smaller of inner radius of throttle pipe, the higher of throttle pressure. The horizontal length of well in deepwater has small effects on the stand pipe and throttle pressure.
????The research can be used to predict annual temperature distribution of horizontal well in deep-water and the solubility of gas in the drilling fluid. The deep horizontal overflow can simulate by combining models. It provides theoretical support for formulate reasonable well control measures. ?。