缝洞型碳酸盐岩油藏流体流动表征方法探讨

Description of Fluid Flow Characteristics for Fracture-cave Carbonate Reservoirs

塔里木盆地缝洞型碳酸盐岩油藏储集空间尺度差异大、流动复杂,很多学者认为渗流理论不能解决其流动表征问题,应该用管流理论解决。为厘清这一问题,从管流与渗流的概念、单相流流动特征及数学表征方法、油水两相流流动特征及数学表征方法3方面,研究了管流与渗流的关系,在此基础上,分析了管流方程描述缝洞型碳酸盐岩油藏流体流动的可行性,并对缝洞型碳酸盐岩油藏流体流动的表征方法进行了探讨。结果表明,从研究的角度,渗流可视为小尺度复杂管道管流;单相流时,管流存在层流、紊流两种流态,渗流也存在层流、紊流两种流态,层流状态,描述管流与渗流的方程是统一的,紊流状态,二者的描述方程不一致,但都是考虑惯性力的影响;两相流时,管流存在多种流型,渗流因尺度小、流型简单,管流基于流型建立了不同的流动表征模型,渗流利用相渗曲线解决两相流问题。说明,管流与渗流并不“冲突”,渗流即是小尺度复杂管道管流,只是由于学科不同、研究对象不同,对流体流动采用了不同的表征方法。缝洞型碳酸盐岩油藏描述不确定大,受油藏描述精度和研究范围的制约,现有管流的处理方法并不适用描述缝洞型碳酸盐岩油藏流体的流动。缝洞型碳酸盐岩油藏的流体流动表征问题应该在渗流力学的架构内,部分借鉴管流的处理方法来解决。

Many scholars believe that the seepage theory can not describe the fluid flow in fracture-vuggy carbonate reservoirs in Tarim Basin which have complex flow and are different in pore scale and pipe flow theory can solve the problem.In order to clarify this problem,the relationship between pipe flow and seepage is studied from three aspects:the concept of pipe flow and seepage,single-phase flow characteristics and mathematical characterization methods,oil-water two-phase flow characteristics and mathematical characterization methods.On this basis,the feasibility of using pipe flow equation to describe fluid flow in fracture-vuggy reservoirs is analyzed,and the characterization methods of fluid flow in fracture-vuggy reservoirs are discussed.The results show that,the seepage can be regarded as small-scale complex pipeline flow;In case of single-phase flow,there are two flow patterns in pipe flow:laminar flow and turbulent flow,and there are also two flow patterns in seepage flow:laminar flow and turbulent flow.The equations describing pipe flow and seepage flow are unified,while the equations describing turbulent flow are inconsistent,but both consider the influence of inertial force.In two-phase flow,there are many flow patterns in pipe flow.The seepage flow is small in scale and simple in flow pattern.Different characterization models are established for pipe flow according to flow patterns,and relative permeability curve is used to solve the two phase flow problem in seepage flow.It shows that there is no“conflict”between pipe flow and seepage flow.Seepage flow is small-scale complex pipe flow,but due to different disciplines and different research objects,different characterization methods are used for fluid flow.Restricted by the accuracy of reservoir description and the scope of research,the existing pipe flow description methods are not suitable for describing fluid flow in fracture-vuggy reservoirs.The characterization of fluid flow in fracture-vuggy reservoirs should be solved within the framework of seepage mechanics,with reference to the description method of pipe flow.