鸡西盆地梨树井田煤系气储层特征及改造工艺探索
Exploration of coal-measure gas reservoir characteristics and reforming technology in Lishu Mine Field of Jixi Basin
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摘要: 煤系中煤层气、致密砂岩气和页岩气叠置组合极具开发潜力,但具有赋存类型多样、成藏组合类型复杂、储层力学性质和工程响应差异大等特点,探索煤系“三气”共探共采技术是实现煤系气经济高效开发的必然要求。研究煤系气储层特征,合理选择目标层位,确定射孔位置,优化压裂施工工艺和参数,实现多类型产气层均衡改造,可最大限度降低层间干扰,充分释放多产气层组的整体产气潜力。本文以鸡西盆地梨树井田HJD1井下白垩统城子河组煤层、煤系泥质岩和煤系致密砂岩互层发育段为研究对象,系统研究了煤系非常规天然气储层特征,优选了煤系气开发有利层段,优化组合了合采产层,探索了与煤系多类型储层特征相匹配的分段射孔、水力压裂工艺,优化了压裂施工流程与工艺参数。结果表明:城子河组煤层与煤系暗色泥岩和砂岩薄互层段含气量高、生烃潜力好,煤系气资源条件优越;优选了煤层与煤层、煤系泥页岩和煤系致密砂岩与煤层、煤系泥页岩-煤系致密砂岩等岩性组合的合采目标层段;优化施工方案为增加射孔段长度(煤层厚度的1.8~6.3倍、砂泥岩含气层厚度的1.2~3.0倍)、提高前置液比例(45%~55%),采用“大液量(1 200~1 800 m3)、大砂量(5.7~10.4 m3/m)、大排量(9.33~10.28 m3/min)、高砂比(7.9%~9.4%)、高注入压力(45.0~46.7 MPa)、多级阶梯式加砂”和投球分压施工工艺,通过煤系多类型储层差异性压裂实现储层均衡改造,达到了较好的体积压裂改造效果。研究工作对煤层群发育区煤系气高效勘探开发具有借鉴意义。Abstract: The superimposed combination of coalbed methane,tight sandstone gas and shale gas in coal measures has great development potential,but it has the characteristics of diverse occurrence types,complex accumulation combinations,and large differences in reservoir mechanical properties and engineering responses. Exploring coal-measure “three-gas” co-exploration and co-production technology is an inevitable requirement for realizing the economic and efficient development of coal-measure gas. Studying the characteristics of coal-measure gas reservoirs,reasonably selecting target horizons,determining perforation positions,optimizing fracturing construction techniques and parameters,and achieving balanced transformation of multiple types of gas-producing layers,can minimize interlayer interference and fully release the overall gas production potential of the gas-producing layer group. In this paper,the interbedded section of the Cretaceous Chengzihe Formation,the coal-measure argillaceous rock and the coal-measure tight sandstone interbedded in the HJD1 well of Lishu minefield in Jixi Basin was used as the research object. The characteristics of unconventional gas reservoirs in coal measures were systematic studied,combined production layers have been optimized,segmented perforation and hydraulic fracturing techniques that match the characteristics of multiple types of coal-measure reservoirs have been explored,and the fracturing construction process and process parameters have been optimized. The results show that the thin interbedded section between the coal seams of the Chengzihe Formation and the dark mudstone and sandstone has high gas content,good hydrocarbon generation potential,and superior coal-measure gas resource conditions; The following seams have been selected:① coal seams and coal seams,② coal-measure shale,coal measures tight sandstone and coal seam,③coal-measure shale-coal-measure tight sandstone and other lithology combination target intervals for combined mining; the optimized construction plan is to increase the length of the perforation section (1.8-6.3 times the thickness of the coal seam,1.2-3.0 times the thickness of sand and mudstone gas-bearing seam),increase the proportion of front fluid (45%-55%),adopt “large liquid volume (1 200-1 800 m3),large sand volume (5.7-10.4 m3/m),large displacement (9.33-10.28 m3/min),high sand ratio (7.9%-9.4%),high injection pressure (45.0~46.7 MPa),multi-stage stepped sand adding” and ball-throwing partial pressure construction technology,realizing well-balanced reformation of reservoirs through differential fracturing of multiple types of coal-measure reservoirs,achieving a good volumetric fracturing reformation effect. The research work is of reference significance for the efficient exploration and development of coal-measure gas in areas where coal seams are developed.