论储层评价中的五性关系

储层空隙空间结构(孔隙、裂缝和溶洞)十分复杂,完全破坏了传统的储层四性关系,在储层评价中暴露出越来越多的矛盾,严重地阻碍了该技术的发展。为此,从展示这些矛盾的根源入手,进行了大量的实例研究,并提出了解决方案。研究表明,复杂空隙结构储层中常见孔隙度与渗透率、孔隙度与含水饱和度、绝对渗透率与有效渗透率、电性与含油气性的矛盾,其孔隙的类型、孔喉大小、裂缝产状等因素是造成这些矛盾的主要原因。在此基础上提出了储层空隙空间几何特性的概念,并分别探讨了定量或定性描述孔隙、裂缝、溶洞几何特性的方法:①孔隙。孔、喉大小与岩石结构和物性、含流体性质的关系;孔隙类型与含流体性质及测井响应特性的关系。②裂缝。产状与孔隙结构指数(m)的关系;径向延伸与深浅探测电阻率的关系;张开度与裂缝渗透率的关系;产状与储层基质岩块含水饱和度的关系;发育指数与岩性的关系。③溶洞。大小、连通状况与m值和3种测井(中子、密度、声波)孔隙度的关系;充填程度与测井响应特性的关系。所建立的储层空隙空间几何特性与岩性、物性、含流体性和电性的五性关系,从根本上提高了复杂储层(如碳酸盐岩等)评价的水平。

A discussion on the relationships between five properties in reservoir evaluation

Reservoir pore spaces (pores, fractures and vugs) are too complex to be predicted by use of the traditional relationships between the four properties of reservoirs, thus more and more contradictions occur in reservoir evaluation. A great number of case studies were performed to reveal the causes of these contradictions and the corresponding solutions were also proposed. For the reservoirs with complex pore spaces, we found four common types of contradictions between porosity and permeability, porosity and water saturation, absolute permeability and effective permeability, and electric property and hydrocarbon-bearing property Those contradictions are mainly caused by pore types, pore throat size and fracture occurrence. On this basis, the concept of reservoir pore space geometry feature was presented and methods were discussed for qualitatively or quantitatively describing the geometrical features of pores, fractures and vugs. The following findings were concluded. (1) For pores, two relationships were established between pores & throat sizes and rock textures, physical properties & fluid-bearing properties, and between pore types and fluid-bearing properties & logging responses. (2) For fractures, five relationships were established between occurrence and pore texture index (m), radial extension and deep/shallow borehole resistivity, openness and fracture permeability, occurrence with matrix water saturation, and between development index and lithology. (3) For vugs, two relationships were established between size & connectivity and m value & three types of logging porosities (neutron, density and sonic), and filling degree and logging responses. These five relationships of reservoir pore space geometrical features with lithology, physical property, fluid-bearing property and electrical property can significantly improve the evaluation of complex reservoirs such as carbonates.