水城矿区煤层气储层特征及压裂改造工艺研究

Analysis of coalbed methane reservoir characteristics and reconstruction process in Shuicheng Mining Area

为了系统评价六盘水煤田水城矿区煤层气资源富集与开发条件,探索与薄-中厚煤层群发育条件相匹配的煤储层改造与合层排采工艺,基于该矿区内施工的3口煤层气井资料,分析了矿区煤储层物性、含气性等特征,并结合工程实践探索了与地质条件相匹配的储层改造工艺。研究表明:上二叠统龙潭组5-2煤、7煤、13-2煤具有单层厚度大、分布稳定、煤体结构完整、含气量及资源丰度高、是区内煤层气开发的主力层位。在正常-超压储层压力条件下,这些煤层含气饱和度高、孔渗性较好,适宜对储层改造后进行煤层气开发。在采用分层射孔条件下,以活性水为压裂液、细-中粒石英砂为支撑剂,采用光套管泵注+可钻式桥塞封隔方式及"大排量、分段阶梯式加砂、多级段塞"工艺实施分层水力压裂,煤储层可取得良好的改造效果。

In order to promote the coalbed methane development of Shuicheng Mining Area in Liupanshui Coalfield,coal reservoir characteristics and geological conditions were analyzed based on materials of three coalbed methane wells. Coal reservoir reconstruction and multi-layer drainage process match with thin and medium thickness coal seams condition were developed from engineering practices.The results showed that No.5-2,7 and 13-2coals of Longtan Formation were main coalbed methane development layers with characteristics of large single layer thickness,stable distribution,complete coal structure,high gas content and high resource abundance. Under normal-overpressure reservoir pressure,these coal seams which have high gas saturation and good permeability are suitable for coalbed methane development after reservoir reconstruction. Coal reservoir reconstruction effect can be improved by using active water and finemedium grain quartz sand as fracturing fluid and proppant for layered perforation process,using light casing pump injection combined with drillable bridge plug as sealing method,using large flow rate,stepwise sand add,multi-stage slug duringmulti-layer hydraulic fracturing processes.