Application of a Novel Temporary Blocking Agent in Refracturing

Abstract

Abstract A novel temporary blocking and A novel temporary blocking agent used as diverting/re-orientation agent in refracturing was introduced in this paper[1]. Laboratory results and field application show that the agent can effectively improve the refracturing well production[2]. The temporary blocking agents include two types, fiber and granular shape. The diverting/re-orientation mechanism is that the fiber agent firstly bridge in the original old fractures, then the granular agent can further accumulate on the shaped bridge in the fracture. And the granular agent can form effective plugging because it is deformable and expandable. Then the new fractures can initiate and propagate along a new path where the direction of in-situ stress has altered after the long-term production from the old hydraulic fracture. Thus the well production can increase because the fracture extend into new oil drainage area. Both of the temporary blocking agents can be completely degraded and the degradation time is controllable, which will bring minimum damage to the formation. Laboratory results show that by "bridging and plugging" the temporary blocking agents can effectively block the old hydraulic fracture. The blocking strength can be up to 40MPa. The main factors affecting temporary blocking strength include the agent volume, size, adding timing, adding speed and manner, etc. These factors can be optimized according to the blocking requirements in fracturing designs. Field case study show that the agents can effectively "bridge and plugging" the old fracture, then the new fracture initiation can be observed obviously. Meanwhile, the production of re-fractured well increased significantly, which is much better than the previous refracturing treatment results in the same oilfield. This novel temporary blocking agents and diverting/re-orientating technology provides effective means which can enhance the controllability, success rate and effectiveness of the refracturing.