Successful Multistage Hydraulic Fracturing in V-Shape Well as a Method for the Development of Coal Bed Methane in China

摘要

There is a rich coal bed methane reserve in the southeast margin of ordos basin. Hydraulic fracturing stimulation is the primary completion method to coal bed methane wellbores for many years in this area. Recently, V-Shape wells, which are complex architecture wells composed of a vertical well and two horizontal wells, are in order to improve recovery of CBM. Two horizontal wells intersect with vertical well in same depth, and the included angle between two well tracks of the plan projection is about 44 degree. Multistage hydraulic fracturing technology was treated two horizontal wells to create fracture network and induce nature fractures. Then, the vertical well was used to drainage to decrease bottom pressure. Based on the geologic parameters, a total of eight stages were placed on two horizontal sections. One had three fractures, the other had five fractures. According to wellbore condition, pump bridge plug technology was used to execute multistage fracturing treatments. During field operation, 7200 m~3 active water was mixed with quartz sand (492m~3) and pumped down two wells together. The averaged proppant concentration was 14%. Because of included angle, the number of sand changed with stage increasing to avoid interference among fractures within two wells. And in the final stage, the treatment deployed 100m~3 sand, and proppant loading reached to about 41750 Kg/m of net coal. This created a new Chinese record of proppant loading in coal bed methane. Consequently, the first V-Shap well group was successfully treated in china. This work can research the application of special technology well in CBM, evaluate the effect of multi stimulation treatments, and confirm the gas content. It also provides the reliable guidance for the reasonable development of CBM reserve in the future.