Application of Digital Rock Technology in Carbonate Tight Gas Development

With the continuous development of unconventional oil resources such as tight oil and gas in China, it is becoming increasingly more important to understand the microscopic characteristics and flow mechanism of tight oil and gas reservoirs through lab studies. It is both time consuming and costly to perform core flow tests in the very low permeability rock samples for field development. This paper described the application of high-resolution digital rock technology performed in North America in the microscopic description and flow mechanism study of the Dengsi carbonate tight gas formation in the central Sichuan area. The study mainly includes: (1) The design and application of multi-scale, multi-resolution different imaging techniques to re-construct a full-diameter digital rock model to realize the three-dimensional characterization of the microscopic pores, vugs and fractures distribution of different reservoir types in the tight matrix; (2) Constructing digital rock models of different resolution and digital fluid models based on field sample and data; (3) Characterizing the permeability and porosity of digital rock models of different resolution and benchmarked against lab measurements to determine the best combination of imaging techniques; (4) Simulation of gas-water relative permeability and recovery from primary depletion at reservoir conditions. Comparing the digital core analysis with experimental results shows that the digital rock technology can be used for the evaluation of tight gas formations and flow mechanisms with high resolution, low cost, and much reduced time. Digital rock models can also be reused which most time is not possible in the lab.