Exploration and application of deep coalbed methane test fracturing technology in Tongxu

Abstract

Deep coal seams are developed in the Shanxi Formation of Tongxu Block, with high gas content, rich free gas, and developed cleat fractures compared to shallow coalbed methane. During fracturing construction, there is large filtration, short fractures are easy to form, and sand addition is difficult. In the early stage, conventional fracturing technology for shallow coalbed methane was used, resulting in high fracturing pressure, difficult sand addition, and unsatisfactory results after fracturing. Aiming at the characteristics of deep coal seam reservoirs and the difficulties in their transformation, pressure drop and in-situ stress tests were carried out before injecting gas pressure into deep coal seams to obtain coal seam parameters and provide a basis for optimizing fracturing design parameters; At the same time, through indoor experiments and numerical simulation research, the saturated sand fracturing technology was explored and tested. On site, the design concept of “large displacement, large-scale, and saturated sand” volume fracturing was adopted for Well Hill 1 Coal Seam A to complete the fracturing construction. The maximum construction displacement was 20 m3 / min, the amount of liquid injected into the ground was 4 315 m3, and the amount of sand added was 347 m3, which was 7 times the strength of conventional fracturing sand addition. The maximum daily gas production after fracturing was 7 299 m3, and the cumulative gas production was 71 509 m3, with significant results. The successful test of this technology provides technical guidance for deep coal seam pneumatic fracturing. © 2023 Well Testing. All rights reserved.