New approach of evaluating fracturing interference based on wellhead pressure monitoring data: a case study from the well group-A of Fuling shale gas field

Abstract

Well pattern infilling has become an effective means for improving the development effect of gas reservoirs in unconventional gas reservoirs. The hydraulic fracturing of infill wells causes widespread fracturing interference between new and old wells. Because fracturing interference has a significant influence on the production of old wells, it is urgent to evaluate the degree of fracturing interference. This paper proposes a new approach to evaluating fracturing interference between new and old wells, which is based on a systematic analysis of the variation pattern of old well wellhead fracturing during the fracturing process of new wells. This new approach not only provides a semi-quantitative evaluation for the degree of fracturing interference between fracture sections of new and old wells but also achieves inter-well connectivity evaluation between new and old wells. This new approach is applied in well group A of the Fuling gas field to demonstrate its analysis process. The results show the different types of fracturing interference result in different levels of pressure response between each fracturing section and the old wells. For example, The pressure rise of old well A7-1 is more obvious in the fracturing process of the 2nd, 14th, and 13th sections of new well A68-5, and the old well A7-2 has significant fracturing interference with the 1st, 2nd, 3rd, 4th, and 6th sections. This achieves a semi-quantitative characterization of fracturing interference between new and old wells. The degree of fracturing interference between the old well A7-2 and the new well A68-5 is the strongest in well group A, which is the effect of compression fracture interference. The old wells A7-3 and A15-3 are the least impacted by fracturing interference, and follow the old wells A15-2 and A7-1. This result has implications for assessing the degree of fracturing interference and inter-well connectivity in unconventional gas reservoirs.