Adaptability Of Horizontal Wells In Qinnan Coalbed Methane Field

The high-rank coal reservoir in the south of Qinshui Basin is a very low permeability reservoir with low porosity,low permeability and strong heterogeneity.Development practice shows that horizontal well development technology is an effective way to improve CBM production speed and development efficiency.The study area began to develop on a large scale in 2006.However,the development performance of horizontal wells in different blocks and different types of wells shows great difference in development effect,high proportion of low production wells,and great difficulty to deal with.Therefore,it is necessary to study the development characteristics of horizontal wells,clarify the main control factors of single well production,guide the optimization design and stimulation of horizontal wells in the study area to adapt to geological characteristics,so as to achieve high-efficiency development,and provide theoretical basis and practical experience for the popularization and application of horizontal wells.This paper analyzes the development status of horizontal wells in the study area,summarizes the development effect and characteristics,carries out the research of high-rank coal reservoir characteristics,and makes clear that gas-bearing,permeability,local microstructure,coal structure,In-situ stress and other factors are the main controlling geological factors of single well production with the combination of the development characteristics.The geological adaptability of horizontal wells under different reservoir conditions was analyzed,and the stimulation technology of low production wells was studied.The stimulation technology of wellbore reentry,hydraulic fracturing for casing horizontal wells,fishbone shape horizontal wells and nitrogen fracturing technology for screen horizontal wells were put forward.Good stimulation effect has been seen after application,and some experience has been provided for other Coalbed Methane fields to optimize the initial development mode and comprehensive treatment in the later period.The results show that open hole multi-branch horizontal wells are suitable for the Coalbed Methane development areas with simple structure,good reservoir property and primary structure.Single screen horizontal Wells are suitable for high or relatively high permeability Wells.Casing fracturing horizontal Wells can effectively solve the difficulty of reserve production in low permeability reservoirs and difficulty of fracturing for straight wells in structural coal development zones,but the technology still needs optimizing.For the development of high-rank CBM,it is the only way to improve the gas production of single well by increasing the control area of single well,while the constant optimization of the casing fracturing horizontal well technology is the only way for the healthy and efficient development of high-rank CBM horizontal Wells.The results show that open hole multi-branch horizontal Wells are suitable for coal development areas with simple structure,good reservoir property and primary structure.Single screen horizontal Wells are suitable for high or high permeability Wells.Casing fracturing horizontal Wells can effectively solve the problems of difficult reserve production in low permeability reservoirs and difficult fracture production in straight Wells in structural coal development zones,but the process still needs to be optimized.For the development of high-order coal CBM,it is the only way to improve the gas production capacity of single well by increasing the control area of single well,while the constant optimization of the casing fracturing horizontal well technology is the only way for the healthy and efficient development of high-order coal CBM horizontal Wells.