扇面水力喷砂定向射孔压裂技术在煤层气井中的应用

APPLICATION OF ORIENTED SECTOR PERFORATION FRACTURING WITH HYDRAULIC SAND BLASTING IN CBM WELLS

煤储层具有低压、低渗、低饱和的特点,其力学特性具有杨氏模量较低、上下隔层应力差小、天然割理裂缝发育等特点。目前煤层气井采用的射孔方式绝大多数为电缆射孔,压裂工艺采用大排量大规模活性水压裂,在压裂施工中不易控制裂缝形态,尤其是裂缝高度。为此,研发了扇面水力喷砂定向射孔压裂技术。该技术是集扇面定向射孔、压裂一体化技术。工艺目的是减小煤层裂缝的复杂形态,在煤层内易形成较长且简单的支撑裂缝以及起到储层防护的作用。该技术主要通过对喷枪水力参数的设计和水力试验,优化喷射器的结构参数,解决了喷砂器精确定位、定向射孔压裂和水力冲蚀等问题,并在现场顺利完成试验应用,压后排采效果比较明显。

Coal reservoir is characterized by low pressure,low permeability and low saturation. Its mechanical properties are low Young modulus,small stress difference between upper and lower layers,and development of natural cleat fractures. At present,most of the perforation methods used in CBM wells are cable perforation. The fracturing technology used is large displacement large scale active water fracturing. And it is difficult to control the fracture pattern during frac,especially the fracture height. Therefore,the research and development of oriented sector perforation fracturing with hydraulic sandblasting is performed. The technology is a set of oriented perforating and fracturing integration technology. The purpose of the process is to reduce the complex shape of coal seam cracks,to form long and simple supporting cracks in the coal seam,and so to protect the reservoirs. The technology mainly solves the problems of accurate positioning,oriented perforation fracturing and hydraulic erosion of the sand sprayer by hydraulic parameters design and hydraulic test of the spray gun,and the structure parameters of the injector are optimized. It has successfully completed the test application in the field. The production after the fracturing is improved obviously.