贵州省织金地区煤层气多层合采层位优选

贵州省织金地区龙潭组煤层具有多、薄特点。与单一厚层状煤层相比，多煤层合采存在合采兼容性问题，易发生层间干扰，影响合采效果及资源动用程度。为了发挥煤层气井生产潜力，提高开发效益，亟需开展合采层位优选，建立多煤层开发序列。在研究织金区块地质特征的基础上，开展了多煤层地质条件差异研究，结合排采实践及解吸理论，探讨了织金地区多煤层合采影响因素，优选了合采层位。多煤层合采主要受解吸液面高度、纵向跨度、压力梯度、供液能力、渗透率差异影响。织金区块上二叠统龙潭组主力煤层地层供液能力、压力梯度、渗透率差异较小，对合采效果影响较小。层间跨度和解吸液面高度差异是影响区块合层开采的关键因素，16，17，20，23，27，30号煤层90 m跨度可作为一个开发组合，大井组优选此6层煤合采获得2 000 m³/d稳定产量，证实合采层位优选方法正确。

Optimization of multi-layer commingled coalbed methane production in Zhijin area,Guizhou province

Coal seams of the Longtan Formation in the Zhijin area of Guizhou province present the characteristics of multiple layers and small individual thickness.Compared with single thick-layered coal seam,multiple coal seams have differences in reservoir pressure gradient,formation liquid supply capacity,permeability and desorption pressure,which affect the efficiency of combined mining and the degree of resource utilization.In order to enahance the production potential of coalbed methane and improve the economics,it is valuable to optimize commingled production and establish a multi-seam development sequence.In view of these problems,this paper carried out a study on the differences of geological conditions of multiple coal seams.Combined with drainage practice and desorption theory,the influencing factors of multi-layer commingled production in the Zhijin area were discussed,and the production strategy was optimized.The results showed that desorption liquid level height,longitudinal span,pressure gradient,liquid supply capacity and permeability difference are the key factors affecting multi-layer commingled production.The main coal seams in the Upper Permian Longtan Formation in the study area have small differences in liquid supply capacity,pressure gradient and permeability,hence these have less impact on commingled production.The differences in longitudinal span and desorption liquid level height are the key factors affecting commingled production in the study area.A 90 m span can be used as a development combination for coal seams no.16/17/20/23/27/30.A practice in large well group obtained a stable production of 2000 m 3/d,proving that commingled production is viable.