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煤储层压力是影响煤层气开发地质条件评价和钻完井、增产改造技术工艺设计以及排采制度制定的重要参数,获得可靠的煤储层压力参数并认识其区域分布规律,对于指导煤层气高效开发至关重要。以沁水盆地中南段潞安矿区山西组3~#煤层为对象,分析发现前期煤储层压力数值可靠性不足,改进并应用大时长关井注入压降套管试井方法,完成了潞安矿区34口煤层气井的储层参数测试和压力特征的系统研究。结果表明:(1)大时长关井压降套管试井是潞安低渗透低压储层矿区获得可靠储层压力参数的先进技术和方法;(2)山西组3~#煤层为低压和超低压储层,在800m埋深以浅,平均储层压力梯度为4.2kPa/m,这远低于本世纪初期关于潞安矿区储层压力(6~7kPa/m)的水平;(3)3~#煤层的低压特征与煤层埋深和底板高程线性相关,其区域性分布规律的控制性地质因素是地下水流场和辛安泉域的地面排泄;(4)潞安矿区3~#煤层的低压和超低压储层的保护性增产改造技术工艺亟待开发,这包括压裂液体系,压裂泵注程序、压裂后返排,及时排采施工,以及排采制度的设计和实施;(5)潞安矿区山西组3~#煤层低压—超低压现象的发现对重新认识沁水盆地煤储层压力规律具有重要启发和借鉴。
The pressure of coal reservoir is an important parameter that influences the evaluation of geological conditions of CBM development and drilling and completion, the technological process design of stimulation technology and the development of drainage system. It can obtain the reliable pressure parameters of coal reservoir and recognize its regional distribution rules. Efficient development is crucial. Taking the No.3 coal seam of Shanxi Formation in Lu’an mining area in the middle and southern part of Qinshui Basin as an example, it is found that there is not enough reliability of the numerical value of coal reservoir pressure in the early stage. By improving and applying the well test method of casing injection pressure drop in large duration, Systematic Study on Reservoir Parameters Testing and Pressure Characteristics of 34 Coalbed Methane Wells. The results show that: (1) Well testing and well logging pressure-lowering casing testing is an advanced technique and method for obtaining reliable reservoir pressure parameters in Luan low-permeability and low-pressure reservoir mining area; (2) The low pressure reservoir is shallow at depth of 800m and the average reservoir pressure gradient is 4.2kPa / m, which is much lower than the reservoir pressure (6 ~ 7kPa / m) in Lu’an mining area in the beginning of this century. (3) The low pressure characteristics of the coal seam are linearly related to the depth of the coal seam and the elevation of the bottom plate. The controlled geological factors of the regional distribution are the groundwater flow field and ground drainage of the Xin’an spring area. (4) The technology of low-pressure reservoir protection and stimulation for production increase urgently need to be developed, which includes the fracturing fluid system, the program of the fracturing pump, the return flow after the fracturing, the timely discharge construction, and the design and implementation of the discharge system. (5) The discovery of 3 ~ # coal seam low pressure-ultra-low pressure in Shanxi area of An ore district has important inspiration and reference to re-understand the pressure regulation of coal reservoir in Qinshui Basin.