【作者】 孙辉；

【导师】 李兆敏；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2008， 博士

【摘要】 国内外疏松砂岩油藏生产中广泛存在着出砂问题,出砂是此类油藏开采中遇到的难题之一,它已成为制约油田进一步开发的重要因素。目前对疏松砂岩油藏的出砂机理及预测研究还不够深入,防砂技术也没有和疏松砂岩油藏特点有机结合,工艺的选择存在一定的盲目性和随意性。本文立足于油藏出砂机理研究,将岩石受力变形和地层流体渗流结合起来,开发出砂管理技术;并加强防砂工艺技术适应性评价研究,为防砂工艺的优化选择和进步提供支持。采用岩石力学理论和方法,试验测试了典型疏松砂岩油藏的岩石变形破坏规律和强度参数,其应力应变是非线性关系,本构方程应该选择Druck-Prager准则处理;同时实验研究了不同含水情况下岩芯力学特性和出砂量、出砂指数的变化规律,为不同含水阶段出砂预测研究提供了基础。应用有效应力定律和连续介质力学理论,考虑了流体渗流、储层变形或破坏、液化砂粒运移等众多因素,建立了基于流固耦合形式的动态定量出砂预测模型。出砂机制主要有储层结构破坏产生粗砂和储层剥蚀产生细砂这两类,出砂过程分为两部分:第一部分主要包括孔隙性岩层骨架的变形或破坏作用,第二部分包括流体的流动和砂粒的运移。在理论研究的基础上开发了软件系统,应用顺序Galerkin有限元进行了求解验证,重点模拟分析了油藏、地层、生产参数对出砂趋势的影响和主要防砂工艺下近井地带地质力学参数的时空演化情况。结果表明:随着地层破坏和出砂,炮眼和井筒周围应力会重新分布,地层参数的变化受出砂和应力作用的复杂影响,出砂量是一个波动变化的过程——这一现象与现场和室内的观测是基本一致的。稠油油藏原油黏度高一般采用注蒸汽开采,本文考虑了热对流的影响,建立了蒸汽注入条件下对地层压力、变形和有效应力评价的热-流-固耦合数学模型,采用FEPG软件对注蒸汽井进行了数值模拟。计算结果表明,由于地层流体高温膨胀引起的高压力,会导致位移、变形,甚至地层结构破裂;这说明了油藏热-流-固耦合研究的重要性。在对胜利油区出砂地层岩石结构特征及粒级模型研究的基础上,采用实尺寸防砂方法评价大型物理模拟实验装置,开展了机械防砂工艺适应性评价,主要包括滤砂管与砾石充填防砂试验、挤压与非挤压充填防砂试验、地层粘土稳定与地层填砂后砾石充填防砂试验、砾石充填防砂影响因素试验等。对挤压砾石充填防砂工艺进行了优化研究,在现场应用中取得了良好的效果。更多还原

【Abstract】 Sanding issue can be widely found in weakly consolidated sandstone reservoirs around the world, and which is one of the main factors that restricts further development of the oilfields. The sanding mechanism and prediction research is not very deeply and sand control technology is not effectively combined with the features of the reservoirs which leads to aimlessness and randomness to some extent in sand control method selection.Based on the study of sanding theory, it is necessary to consider the coupled stress and seepage fields and develop sand management technique, and, enhance the adaptability research of sand control technology and support the optimization and improvement of sand control methods.Adopted with the theory and methods of rock mechanics, the deformation and failure laws and strength parameters of the typical unconsolidated sandstone cores were tested, and the results indicate that the relationship of stress and strain is nonlinear, and the Druck-Prager damage criteria is recommended. The changes of rock properties, sand volume and sand index in different water saturation are studied, which can be used to guide sand prediction in different water cut periods.Considering the principle of effective stress and continuum mechanics theory, a coupled fluid-solid model corresponding to fluid seepage, deformation or failure of stratum and fluidized sand movement, etc, is developed to dynamically and quantitatively predict sand production. There are two kinds of sanding mechanisms, which are coarse sand model due to structural failure and fine sand model due to erosion, and the sanding process is mainly includes deformation or failure of stratum and movement of fluid or sand. And then, a software system with the sequential iterative Galerkin finite element method is developed to solve and validate the model. The problems such as sanding trend under different reservoir, stratum, production parameters and near-wellbore variation of geomechanics parameters in time and space with different sand control methods, etc. are simulated and investigated. The results show that stress around the wellbore and perforation tunnels will redistribute along with failure of the formation and sand production; the reservoir parameters are influenced by the complex sanding and stress changes; the volume of sand production will fluctuate and this phenomenon is consistent with field and laboratory observation.In order to solve the high viscosity problem of crude oil, the steam stimulation technology is generally adopted in heavy oil reservoir exploitation. An improved heat-fluid-solid coupling model considering the influence of heat convection is established to evaluate the formation pressure, deformation and effective stress under steam injection conditions, and it is simulated with the finite element program FEPG. The results show that the high pressure caused by the higher thermal expansion of fluid may lead to displacement, deformation or even failure of structure, which show the important ole of heat-fluid-solid coupling during heavy oil recovery.On the basis of size classification research of the main sanding blocks of Shengli oilfield, the evaluation study of mechanical sand control technology is proceeded with the full-size sand control method selection and evaluation apparatus. The experiments mainly include screen liner sand control tests, conventional wire wrapped screen gravel pack tests, high-pressure gravel pack tests, clay stabilization and formation gravel pack tests, the influence tests of fluid viscosity, size of wire wrapped screen and gravel, screen gauge, etc. Then, the high-pressure gravel pack sand control technology is studied and optimized and has good effects in field application.更多还原