GROUPING AND DETERMINING OIL RESERVOIRS IN CARBONATE RESERVOIRS BY THEIR PRODUCTIVITY AT THE STAGE OF GEOLOGICAL EXPLORATION

Abstract

The relevance of the study is caused by the need to assess the productivity of fields in the Volga-Ural oil and gas province which are composed of a carbonate reservoir at the stage of project documents compiling with the aim of determining the profitability and development strategy of these facilities, as significant oil reserves are concentrated there and they are classified as hard-to-recover. Solving this problem allows us to expand the resource base of the region and minimize risks in making management decisions. The purpose of the research is to group objects in carbonate reservoirs with the creation of a methodology for classifying objects going out from exploration into the category of high or low productivity applying indirect data. Objects: oil deposits in carbonate reservoirs of the Volga-Ural oil and gas province. Methods. The method of geological field analysis, some types of factor analysis were used when grouping. Results. It was found that the boundary value of the oil deposits productivity index in carbonate reservoirs, referring the fields into high- and low-productivity, is a value equal to 10 t/day/MPa. It is shown that the separation of deposits by productivity is determined by the reservoir-filtration and thickness properties of the reservoir rocks, as well as the bedding conditions and the reservoir fluids properties. On average, these parameters are higher for highly productive facilities. Low-productivity objects, on average, have high reservoir oil viscosity and density values. It is impossible to clearly match the boundary value of the productivity coefficient to the boundary value of any parameter, since the productivity of the deposits is characterized by a complex of values of the reservoir parameters and the fluids saturating it, and only a set of these values makes it possible to evaluate it. A method was created for differentiating development facilities in Volga-Ural oil and gas province carbonate reservoirs by productivity index basing on indirect data to solve the problems of identifying production facilities in multi-layer fields; comparison of the facilities while conducting the development analysis, etc.

Keywords

• productivity index
• oil
• carbonate reservoirs
• development efficiency
• geological and physical properties of rocks