Prediction of coalbed methane reservoir brittleness index driven by rock physics model

Abstract

The brittleness index (BI) of coalbed methane (CBM) reservoirs is an important reference data for fracturing zone selection and sweet spot prediction, and also an important parameter for CBM reservoir evaluation. Therefore, the research on the brittleness of CBM reservoirs plays a vital role in the exploitation and utilization of CBM reservoirs. Firstly, combined with the mineral composition of coal samples from the actual work area, the rock physics modeling of CBM reservoirs was carried out, and the rock physics template of porosity, mineral composition and brittleness index was constructed Then, the rock physics template is analyzed to obtain the influence of porosity and mineral composition on elastic properties and brittleness characteristics. On this basis, several brittleness index formulas are compared with the reference formulas, and the suitable reservoir brittleness index formula is selected. Finally, based on the actual seismic data, the pre-stack simultaneous inversion is carried out, and the brittleness index of the CBM reservoir is predicted. The comparison between the predicted results and the actual gas production results in the work area shows that the rock physics modeling process and the selection of the brittleness formula in this paper have a good indication for the prediction of the brittleness index of the CBM reservoir. Note: This paper was accepted into the Technical Program but was not presented at IMAGE 2022 in Houston, Texas.