特低渗厚油层多级加砂压裂工艺试验

对于厚度大且层内无明显隔夹层的油层,采用常规压裂工艺改造因支撑剂沉降难以实现油层纵向上的充分动用,纵向延伸过度难以实现造长缝。为改善其压裂改造效果,借鉴下沉剂控缝高压裂原理,从注入级数、压裂规模、注入排量等参数优化着手研究,试验形成了一种多级加砂压裂工艺。该工艺是将总支撑剂量通过多级注入进行铺置,依靠上一级压裂形成的支撑剂砂堤提供应力遮挡改变后续混砂液流向,进一步增加裂缝长度和支撑缝高,从而扩大有效泄油面积。2年来,在华庆油田L油层累计试验242井次,平均单井日增油0.4～1.8t,对特低渗厚油层有较好的增产效果。

Research on multi-stage propped fracturing for ultra-low permeability and thick reservoir

The reservoir with big thickness and no obvious interbed could not be produced sufficiently in longitudinal direction with the conventional fracturing technology because of proppant settlement, and long fractures are hard to be produced because of the big reservoir thickness and excessive vertical extension. To improve fracturing in thick oil reservoir, learning from the fracturing principle that the fracture height is controlled by sinking agents, starting from the optimization of some parameters like injection grade, fracturing scale, and injection displacement, a multi-stage propped fracturing technology is developed. The total amount of proppant is deployed by multi-stage injection, as well as the propped fracture of previous stage provides stress shielding, fracture length and propped height can be further increased, and then, effective drainage area is enlarged. In the past two years, multi-stage propped fracturing experiment has been conducted on 242 wells in L oil reservoir in Huaqing Oilfield, the average incremental oil was 0.4 to 1.8 t for single well. It is proved that the new technolgy could better stimulate the production of ultra-low permeability and thick oil reservoir.