Research on Laboratory Evaluation of Coalbed Methane Reservoir Water Blocking Damage Removal in Hancheng Block

Abstract

Owing to factors such as production system change, pump shutdown and workover, there was sudden drop in formation fluid velocity of coalbed methane well in Hancheng block, resulting in water blocking damage, the gas production plunged after the well was reopened. In order to remove the water blocking damage of coalbed methane reservoir, this paper integrated extensive survey, initially selected two nonionic surfactants (B4-B5) and three anionic surfactants (B1-B3) as the experimental subjects. The results showed that the mixed effect of B3 and B5 is the best. In order to further improve the formula system, the experimental study on the selection of auxiliaries was conducted, the results showed that under the premise of meeting environmental protection, ethanol could play a good role in reducing surface tension and defoaming, and the effect was best when the addition amount was 3%. The formula of coal seam water blocking agent PT was determined through the laboratory water-blocking evaluation experiment, and laid the foundation for the subsequent field test.

Development scheme screening considering reservoir damage based on the AHP model

“…The chemical solutions of two nonionic surfactants and three anionic surfactants are obtained. The results show that ethanol has good surface tension and defoaming effect, and the best addition amount was 3% [14].There still is a lack of research examples of reservoir evaluation for specific blocks because different blocks have different geological conditions. Making and adjusting a development plan through research results on reservoir damage can improve the oil recovery and reduce the economic cost.…”