Abstract:
With the large-scale construction and production of deep coalbed methane horizontal wells, the problem of inter-well frac hit has become more and more obvious, which seriously affects the normal production of neighboring wells. In order to avoid and slow down the occurrence of inter-well frac hit and promote the efficient recovery of tampered wells, we systematically carry out the evaluation of inter-well frac hit by taking the deep coalbed methane horizontal wells of Daning-Jixian block in the eastern edge of Ordos Basin as the research object. Firstly, based on the production and experimental parameters such as gas production, liquid production and chloride ion concentration before and after the pressure frac hit, the quantitative indexes of the influence degree of the pressure frac hit between wells were established, and the influence degree of the pressure frac hit was classified into three grades from weak to strong, which were Ⅰ (weak interference), Ⅱ (medium interference) and Ⅲ (strong interference) in the order of the degree of influence of the pressure frac hit. Then, based on the objective geological conditions of Daning-Jixian block and the understanding of development and production practice, using the multi-factor gray correlation analysis method, we evaluated four categories and nine sub-factors of influencing factors, such as development and deployment (distance between wells, location of horizontal section, vertical depth), geology (strength of natural fracture), engineering (average scale of single-cluster fluid, number of perforation clusters, scale of single-section fluid, and construction displacement), and drainage and extraction (production time of the parent well), the distance between wells, production time of the parent well, average single-cluster fluid size, and natural fracture were identified as the main control factors for the pressure frac hit of deep-seated coalbed methane horizontal wells in Daning-Jixian block, and corresponding preventive countermeasures were developed based on these factors. Finally, based on the analysis of the strength of the influence degree of pressure frac hit between wells and the main controlling factors of pressure frac hit, four types of high-efficiency production recovery measures, such as conventional drainage, strong drainage measures, oil-linked segmental drainage, and replacement of gas extraction process, are formed in a targeted and differentiated manner according to the drainage needs of pressure frac hit wells from weak to strong. The field test shows that the research results are of great significance for reducing the pressure frac hit between wells and efficient production recovery in Daning-Jixian block.