A combined stimulation technology for coalbed methane wells: Part 2. Application

Based on the theory and technology of combined stimulation, this paper, the second of a two-part series, presents an application of the combined stimulation technology to a low-deliverability CBM well in the Sunan Syncline, Anhui Province, China. During the stimulation, a low-damage fracturing fluid was adopted. Based on the laboratory test results, the property of the low-damage fracturing fluid is analyzed. Additionally, the stimulation effect is evaluated according to the calculation of the reservoir permeability and the drainage conditions. Results show that the low-damage fracturing fluid has good compatibility with the reservoirs, and can effectively prevent the reservoir to be damaged by water sensitivity, water blocking effect and flow rate sensitivity, and decrease the migration resistance of fracturing fluid in both tubing and reservoir fractures. The calculated reservoir permeability during the stimulation indicates good fracturing results for different kinds of reservoirs. The reservoir permeability at the early drainage stage after the combined stimulation is 3.4 times of the reservoir permeability after the first stimulation of this well. After conducted the combined stimulation, the daily gas production of the well has excessed 1000 m3/d since 21st December 2017 which indicates a successful application of this technology.