郑庄区块高阶煤层气低效产能区耦合盘活技术

高阶煤层气井低产低效区的普遍存在,已成为制约我国煤层气产业发展的主要瓶颈之一。沁水盆地郑庄区块有2/3的矿井属于低效井,区块整体经济效益差,以郑庄区块为例,剖析造成高阶煤煤层气低效开发问题的影响因素,提出了低效区盘活技术策略和模型。建立了井网部署方式、储层改造适应性技术、高效排采管控方式3个方面的优化技术,形成了适用于高阶煤储层煤层气井增产的技术系列:一是基于开发动态分析和数值模拟的开发井型井网优化技术和水平井耦合降压盘活直井技术;二是基于煤储层特征及煤层气开发机理分析的高阶煤储层疏导式储层改造技术;三是基于煤储层气-水赋存机理和微裂隙气-水流动机理的高效排采管控技术。在此基础上,提出了郑庄区块低效产能带耦合盘活的工艺技术思路:以资源有效动用为核心,通过调整井网井型,采取疏导式储层改造技术和高效排采管控模式,实现低效区带整体协同降压,新井高效开发,老井稳定增产,达到区块整体盘活的效果。建立了低效区整体盘活工艺技术模型,并在郑庄区块进行了现场试验。为期3 a的现场试验取得了显著的开发效果:44口直井平均单井日产气量2 400 m~3,是周围老井峰值产气量的3.6倍;22口水平井盘活试验井产量是调整前水平井的4.2倍,耦合降压使得周围低产直井平均单井日产气量提高了435 m~3,试验区采气速度由调整前的1.8%提高为目前的7.6%,提高了区域煤层气储量动用程度和采气速度,使区块开发经济效益转亏为盈。该项技术的研发成功,为国内类似地质条件煤层气低效区盘活提供了示范和借鉴。

Coupled activation technology for low-efficiency productivity zones of high rank coalbed methane in Zhengzhuang block,Shanxi,China

The prevalence of low yield and low efficiency areas in high rank coalbed methane wells has become one of the main bottlenecks restricting the development of coalbed methane industry in China.In Zhengzhuang block of Qinshui Basin,two thirds of wells are low efficiency wells,the economic benefit of the block is poor,therefore,the influence factors causing the low efficiency development of high rank CBM wells of Zhengzhuang block were analyzed to study the technical measures of activating the low efficiency blocks.Through the research of the well pattern type,reservoir reconstruction adaptability,and high efficiency drainage and production control mode,a series of technologies,including development well type and well pattern optimization technology and vertical well activating technology with horizontal well coupling depressurization based on the dynamic analysis and numerical simulation,high rank coal reservoir reconstruction technology based on the analysis of the coal reservoir characteristics and the CBM development mechanism and high efficiency drainage and production control technology based on gas water occurrence mechanism of coal reservoir and micro fracture gas water flow mechanism,suitable for the wells of high rank coal reservoir stimulation had been developed.On this basis,the idea of coupling and activating technology for low yield and low efficiency area was put forward to take effective use of resources by adjusting the pattern and well type,applying reservoir reconstruction technology and high efficiency drainage and production control technology.Then an activation model of low efficiency block was established to achieve the effect of overall activation of the block with the pressure declining synergistically,the new wells efficient development and the gas production steady improvement of old wells.Three years field experiments in Zhengzhuang block have achieved significant development results,such as,the average daily gas production of 44 wells is 2 400 m3,which is 3.6 times that of the peak daily gas production of the surrounding old wells,the daily gas production of 22 experiment horizontal wells is 4.2 times that of the pre adjustment horizontal wells,and the gas production rate increases from 1.8% to 7.6%,which have greatly improved the degree of producing reserves recovery and the gas production rate,as a result,the economic benefit of the block has been turned from loss to profit.The successful research and development of the technologies provide good references for activating other low efficiency blocks with similar geological characteristics.