GW-CP194-80M型煤层气双保压取心工具研制及现场试验

在煤层气取心过程中,煤心经过压力释放和取样操作,含气量与渗透率发生重大变化,测量数据失真,严重影响煤层气开发方案的制订。为获取覆压下原始状态煤心,减少因地层环境改变引起的煤心测试误差,研制了GW-CP194-80M型煤层气双保压取心工具。工具采用气液压力补偿技术和复合式胶筒保压内筒,可使岩心保持原始地层压力和适当围压,防止微裂缝的形成,还可实现地面带压拆卸,直接进行渗透率测试及临界解吸压力特征观测等后续测试实验。通过室内实验和现场试验表明,GW-CP194-80M型煤层气双保压取心工具性能可靠,技术可行,能有效保护岩心结构,达到双保压设计要求。该工具的成功研制,将为煤层气合理制订开发方案及精确计算含气储量提供重要的技术支持。

Development and Field Test of GW-CP194-80M CBM Dual Pressure Coring Tool

During the CBM coring process, there is a great variation for the gas content and permeability due to pressure release and sampling operation, which will distort the corresponding test data and seriously influence the formulation of CBM development program. the GW-CP194-80M CBM dual-pressure coring tool was developed to obtain the original core sample under overburden pressure and reduce the test error caused from the formation condition variation. Gas-liquid pressure compensation and a compound rubber pressure-holding cylinder were used to hold the original formation pressure and proper confining pressure to prevent the creation of micro fractures. The sample can be directly used to permeability, critical desorption pressure and other subsequent tests through disassembly under pressure eon the ground. Laboratory field tests indicates that the GW-CP194-80M CBM dual-pressure coring tool is characterized by reliable performance, technical feasibility, effective maintenance of sample structure and favorable dual-pressure performance. This coring tool could provide certain technical reference for the reasonable formulation of CBM development program and accurately determine reserves.