摘要
为了提升注空心球变梯度控压钻井中井下分离器的分离效率,并准确掌握井筒压力的分布规律,研制了以球形过滤塞和金属过滤网为核心结构的新型井下过滤分离器,对其总体结构和工作原理进行了阐述;以多孔介质模型对过滤结构进行模拟,并引入欧拉多相流模型对钻井液和空心球混合流体的流动过程进行数值模拟研究,分析了不同注入速度或空心球体积分数对过滤分离器分离效率的影响规律;基于自主研制的变梯度控压钻井室内模拟试验系统,开展了过滤分离器分离效率的敏感性试验,研究了泵排量、空心球体积分数、密度和直径对分离效率的影响;依据数值模拟和室内试验研究所得分离效率,并考虑井筒与地层间能量交换、井筒温度和压力对流体物性参数的影响,建立了深水变梯度控压钻井单相流条件下瞬态井筒温压耦合模型。利用有限差分和高斯赛德尔迭代方法分别对模型进行离散和求解,对不同变梯度参数(如分离器位置、数量、空心球体积分数或密度等)条件下的井筒压力分布规律进行了敏感性分析。研究结果表明:过滤分离器可以显著提升分离效率,最高可以达到98.5%;环空压力在过滤分离器位置处存在明显的拐点,总体呈折线形分布且拐点位置、数量与分离器的位置和数量同步变化;井筒压力与分离器数量、分离器距离井口的深度以及空心球体积分数呈负相关,与空心球密度和排量呈正相关。该研究可以为深水变梯度控压钻井方法的进一步发展提供一定的理论参考。
In order to improve the separation efficiency of the downhole separator in injecting the hollow glass spheres(Referred to as HGS) for variable gradient managed pressure drilling(Referred to as MPD), and accurately grasp the distribution law of wellbore pressure, the new type of downhole filter separator with spherical filter plug and metal filter screen as the core structure were developed in this paper, and its overall structure and working principle were expounded. The filter structure was simulated by the porous media model, and Euler multiphase flow model was used to simulate the flow process of the mixed fluid of drilling fluid and HGS in wellbore, and then the influence of injection rates of different fluid or volume fraction of HGS on the separation efficiency of the filter separator was analyzed by numerical simulation. The sensitivity experiment of the separation efficiency of the filter separator was carried out under different influencing factors, such as pump flow rate, density, volume fraction and diameter of HGS based on the self-developed laboratory simulation experiment system for variable gradient MPD. According to the separation efficiency obtained from numerical simulation and laboratory experiments, and considering the energy exchange between the wellbore and the formation as well as the influence of the wellbore temperature and pressure on the physical parameters of the fluid, a transient model of the coupled wellbore temperature-pressure under the single-phase flow condition for variable gradient managed pressure drilling in deep water was established. The finite difference and Gauss-Seidel iteration methods were used to discretize and solve the model respectively, and the sensitivity analysis of distribution law for the wellbore pressure under the condition of HGS volume fraction or density, the position or number of the filter separator was carried out. The study results showed that the new downhole filter separator can significantly improve the separation efficiency, of which the maximum
作者
张锐尧
李军
柳贡慧
ZHANG Ruiyao;LI Jun;LIU Gonghui(College of Petroleum Engineering,China University of Petroleum-Beijing,Beijiing 102200,China;College of Petroleum Engineering,China University of Petroleum-Beijing at Karamay,Karamay 840000,China;Beijing University of Technology,Beijing 100022,China)
出处
《石油科学通报》
2022年第4期564-575,共12页
Petroleum Science Bulletin
基金
国家自然科学基金“深水油气钻采井筒压力控制基础研究”(编号:51734010)资助。
关键词
变梯度钻井
过滤分离器
分离效率
压力预测
variable gradient drilling
filter separator
separation efficiency
pressure prediction
