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为了提高沁水盆地南部煤层气压裂、排采技术适应性,采用数值模拟和动态分析方法,研究了压裂裂缝形态与产能的关系、不同排采阶段控制机理与要点、煤层气井产水特征及其对产气的影响,建立了复杂裂缝条件下产能分析方法、煤层可动水及外来水侵评价方法.认为地质条件及压裂工艺控制裂缝发育形态,在低渗煤层中形成一条高导流的压裂主裂缝至关重要.研究结果表明:在渗透率为0.1~1.0mD低渗煤层中形成一条高导流的主裂缝越长,产气效果越好.排采方面,单相水流阶段应以降低应力敏感伤害、扩大压降为主,该阶段排采时间6~10个月以上、降液速度2~5m/d、可动水排出30%以上、压降半径大于120m(已产生井间干扰)的井易高产;两相流初期上产阶段应控制好动液面、套压和气体瞬时流速,保证气、水稳定产出,降低不稳定流动造成的附加伤害.煤层气井产水特征、产水量大小及煤层中水的采出程度决定后期产气效果,而煤层中原始可动水量大小、外来水体规模及侵入程度控制产水量及压降,据此可指导排采管控.
In order to improve the adaptability of CBM fracturing and discharge technology in the southern Qinshui Basin, numerical simulation and dynamic analysis are used to study the relationship between fracturing fractures and productivity, control mechanism and key points in different drainage stages, water production characteristics of CBM wells And its influence on gas production, a method of productivity analysis under complicated fractures, a method of evaluating movable water and external water invasion of coal seam are established.It is considered that geological conditions and fracturing process control the development pattern of fractures, and a high conductance The main fractures of the flow are very important.The results show that the longer the main fractures forming a high flow in the low permeability coal with the permeability of 0.1 ~ 1.0mD, the better the gas production is.As for the discharge, the single-phase flow Stage should be to reduce the stress-sensitive injury, expanding the main pressure drop, the stage of mining time 6 to 10 months or more, the rate of liquid down 2 ~ 5m / d, movable water discharge more than 30%, pressure drop radius greater than 120m Producing cross-well interference) is easy to produce high yield; the initial stage of two-phase flow should control the good liquid level, nesting pressure and gas instantaneous flow rate to ensure stable output of gas and water and reduce the additional damage caused by unstable flow. Water production characteristics, production The amount of water and the degree of recovery of the water in the coal seam determine the effect of gas production in the later period. However, the original amount of movable water in the coal seam, the size of the external water body and the degree of invasion control the water yield and pressure drop, which can guide the discharge control.