【作者】 王海静；

【导师】 高存法；

【作者基本信息】 南京航空航天大学 ， 固体力学， 2012， 博士

【摘要】 水平井技术是一项高效的油田开发、挖潜、提高采收率技术，近年来在油气勘探与开发中得到了广泛的应用。水平井注采过程中，井筒与油藏互为边界条件，相互影响，相互制约，构成了一个复杂的井筒-油藏耦合动力学系统。开展水平井井筒-油藏耦合问题的理论及试验研究，对于认清井筒、油藏耦合机制，预测注采动态，优化注采方案，提高水平井开发效果具有十分重要的意义。本文重点开展了以下几方面工作：1、从井筒、油藏流动特征及耦合机理出发，基于固体力学、流体力学、渗流力学、传热学等相关理论，采用连续介质力学方法建立了一个综合的水平井井筒-油藏耦合数学模型。其中，井筒自由流采用Navier-Stokes（NS）方程描述，油藏多孔介质渗流采用Darcy定律（DL）描述。该模型在考虑井筒管流与油藏渗流耦合的同时，还考虑了流场与温度场以及岩体变形场之间的耦合，为水平井井筒-油藏系统动态特性研究提供了理论依据。2、利用Brinkman（BR）方程描述井筒自由流与油藏多孔介质渗流之间的近井过渡流，建立了基于NS-BR-DL耦合的井筒管流与油藏渗流耦合方法，为井筒管流与油藏渗流耦合过程的准确描述以及耦合机制的深入研究提供了新的途径。其中，NS方程和BR方程采用稳定化Galerkin最小二乘有限元离散，DL方程采用标准Galerkin有限元离散，三类方程同时联立求解。在前人研究的基础上，考虑井筒在不同流动形态下径向流入/流出对其沿程压力损失的影响，提出了改进的等效渗流模型及方法，为油田级大尺度井筒管流与油藏渗流耦合数值模拟提供了有效途径。3、在改进等效渗流法基础上，针对热-流-变形耦合条件下的水平井井筒-油藏双重耦合问题，提出了基于Galerkin有限元空间离散技术和二阶向后差分时间离散技术的迭代求解方案。热对流扩散方程采用稳定化人工粘性方法求解，避免了对流占优条件下标准Galerkin有限元法的伪数值震荡问题。定量分析了水平井注汽和采油过程中井筒-油藏系统的温度、压力、应力、孔渗特性时空变化规律和动态耦合关系。4、基于源函数思想和势的叠加原理，建立了渗流-变形弱耦合条件下均质各向同性油藏水平井井筒-油藏耦合问题的半解析方法，并通过坐标变换和非均质性定量表征等一系列手段将该方法推广到大斜度井和非均质、各向异性油藏，为水平井注采动态的快速预测提供了有效的途径。定量分析了井斜角、渗透率非均质性和各向异性对水平井流入动态及流量/压力剖面的影响。5、基于势的叠加原理，将定量表征孔眼汇聚流及近井地层损害的经验表皮系数法与源函数法相结合，实现了射孔水平井井筒-油藏耦合问题的半解析求解。在此基础上，提出了通过变孔深、变孔密射孔调整非均质油藏水平井产液剖面的新方法，为水平井射孔方案设计提供了理论依据。定量分析了套管尺寸和近井非均质性对水平井变参数射孔的影响。6、基于流动相似理论，开展了射孔水平井井筒-油藏耦合的地面小比例模型试验。通过不同射孔方案下射孔井段的流量数据对比，验证了水平井变参数射孔方法的调剖效果，并提出了相关应用建议。在此基础上，采用Visual Basic编程语言开发了配套的水平井射孔优化设计软件，对油田现场10口水平井的射孔方案进行优化设计，通过优化前后生产数据测试结果对比，进一步检验了变参数射孔调剖方法的应用效果。更多还原

【Abstract】 Horizontal well technology is an efficient oilfield developing and potential tapping technology,which enhances oil recovery and has been widely used in oil and gas exploration and development inrecent years. During injection and production processes, wellbore and reservoir influence and restricteach other, constituting a complex wellbore-reservoir coupling dynamical system. Theoretical andexperimental studies on wellbore-reservoir coupling for horizontal wells are significant for therecognition of coupling mechanism and the prediction of injection/production performances. Theresults can also guide the optimization of injection/production programs and improve the developmenteffect of horizontal wells.In this paper, the main works are as follows:1. Considering the flow characteristics and coupling mechanism of wellbore and reservoir, acomprehensive wellbore-reservoir coupling model is developed by using continuum mechanicsapproach, based on the theories of solid mechanics, fluid mechanics, seepage mechanics and heattransfer. In this model, the free flow in wellbore is described by Navier-Stokes equation (NS), and theporous media flow in reservoir is described by Darcy Law (DL). Not only the coupling of wellboreflow and reservoir flow, but also the coupling of fluid flow, heat transfer and rock deformation, aretaken into account in this model, which provides a theoretical basis for the dynamic characteristicstudy of wellbore-reservoir system.2. By using Brinkman equation (BR) to describe the near-well transitional flow between the freeflow in wellbore and the porous media flow in reservoir, a NS-BR-DL-based approach to couplewellbore flow and reservoir flow is established, which provides a new way for more accuratedescription of the coupling process and further study of the coupling mechanism. In addition, theNavies-Stokes and Brinkman equations discretized by Galerkin/least-squares finite element method,along with the Darcy Equation discretized by standard Galerkin finite element method are solvedsimultaneously. On the basis of previous research, an improved equivalent permeability model andmethod is developed, considering the influence of radial inflow/outflow on the pressure loss along thewellbore under different flow patterns. The results can provide an effective way for the oilfield-level,large-scale numerical simulation of coupled wellbore flow and reservoir flow.3. Based on the improved equivalent permeability method, an iterative solution method isestablished for double coupled wellbore-reservoir problems under the thermal-hydro-mechanicalcoupling conditions. This method uses standard Galerkin finite element method for spatial discretization and second order backward difference method for temporal discretization. The thermalconvection diffusion equation is solved by using stabilized artificial viscosity method, which avoidsspurious oscillations of standard Galerkin finite element method under convection dominatedconditions. Considering the wellbore-reservoir system in both steam injection and oil productionprocesses, temporal/spatial variations and dynamic coupling relationships of temperature, pressure,stress, porosity and permeability characteristics are analyzed quantitatively.4. Based on the idea of source function and the principle of potential superposition, asemi-analytical method for wellbore-reservoir coupling problems is developed for horizontal wells inhomogeneous isotropic reservoirs under weak hydro-mechanical coupling conditions. Extended by aseries of measures, such as coordinate transformation and heterogeneity quantitative characterization,this method can also apply to highly deviated wells and heterogeneous, anisotropic reservoirs,providing an effective way for quick prediction of injection/production performances of horizontalwells.. The effects of deviation angle, heterogeneity and anisotropy on the inflow performance andflow/pressure profiles of horizontal wells are studied quantitatively.5. Based on the principle of potential superposition, empirical skin factor method for quantitativecharacterization of perforation convergence and near-well formation damage is combined with sourcefunction method for the semi-analytical solution of wellbore-reservoir coupling problems ofperforated horizontal wells. On this basis, a new method for adjusting production profiles ofhorizontal wells in heterogeneous reservoirs through variable-depth and variable-density perforatingis proposed, which provides a theoretical basis for the design of perforating program of horizontalwells. The effects of casing size and near-well heterogeneity on variable-parameter perforating areanalyzed quantitatively.6. Based on the theory of flow similarity, ground small-scale model tests of perforatedhorizontal-well wellbore-reservoir coupling are carried out. Comparing flow data of perforatedsegments under different perforating programs, the effect of adjusting production profiles of thevariable-parameter perforating method is verified and some related recommendations for applicationare given. On this basis, a perforation optimization software for horizontal wells is developed inVisual Basic, by which the perforation programs of10horizontal wells in oil field are optimized.Through comparison of production data before and after optimization, the effects of thevariable-parameter perforating method are further examined.更多还原