A Dynamic Classification Method of the Sinian Dengying Formation Heterogeneous Carbonate Reservoir

Abstract

The Sinian Dengying Formation carbonate reservoir dominated by matrix pores and vugs in the Gaoshiti-Moxi area is characterized by strong heterogeneity. Such reservoirs with their tight matrix is identified as low-porosity and low-permeability, and yet with naturally-occurring fractures and dissolution vugs. To improve the reservoir exploitation, optimal production parameters specific to each type of gas wells are required. This paper summarized the geological and production indexes of this reservoir, classified the gas well into varied types based on the pressure build-up well testing, modern production decline analysis and reservoir geological data analysis, and also concluded the identification method of the gas well type. The gas wells in this reservoir were divided into four types, which respectively present the fluid flow characteristics of drilling through the large fracture-vug system, drilling through the fracture-vug with connectivity to the surrounding, drilling through the isolated fracture-vug and at last drilling through the reservoir matrix. The dynamic reserves of different types of gas wells vary considerably, while a positive correlation is seen between the dynamic reserves and effective reservoir thickness in terms a specific type of gas wells. This research carried out classification of the gas well, and correspondingly proposed the identification method, on the basis of the analysis on the geological and production data of the gas reservoir, which lays down the foundation for further production parameter optimization for the production well in the Sinian gas reservoir of this area and accelerates the production capacity building progress of the reservoir in a scientific manner.