Experimental Study On Temporary Plugging Steering Fracturing Of Tahe Carbonate Reservoir

Tahe oil field is a carbonate-gap-hole type oil reservoir,which is dispersed.The general fracturing can only form a main fracture,which is not conducive to improving production efficiency.Therefore,it is urgent to develop temporary plugging and fracturing technology to improve reservoir production.In this paper,the temporary plugging steering fracturing experiment and the comprehensive performance evaluation experiment of temporary plugging agents have been carried out.At first,the temporary plugging steering fracturing experiment was carried out.Under the conditions of different temporary plugging agent types,size,dosage and difference in ground stress,the fracturing experiments were carried out in straight wells and horizontal wells to study the law of fracture initiation,steering and extension.And determine the demand for temporary plugging strength of agents in fracture entrance and interior.Then the comprehensive performance evaluation experiment of temporary plugging agent was carried out,which included temporary plugging evaluation,stability evaluation,degradation evaluation.The temporary plugging evaluation uses 3D printing technology to make the rock slab simulating the actual formation fracture.Under the condition s of different fracture width,the different agent types,concentration,displacement,size are formed,which can meet the temporary plugging demand.Then the law of laboratory experiment is extended to the field for the design of temporary plugging agent combination.The stability of temporary plugging agent is evaluated by observing the degradation of agent in hydrochloric acid solution at high temperature condition.The degradation performance of agent is evaluated by observing the degradation under formation condition.The results show that in the straight well,both the temporary plugging in fracture entrance and interior can hold up pressure to open the new fracture and form the complex fracture.The new fracture mainly expands from the natural fracture and the bedding area.Horizontal well temporary plugging subsection fracturing can open natural fractures or bedding to form multiple cross-section fractures,but lack of natural fractures or bedding in homogeneous artificial rock samples can only form simple fractures.Through the combination of fiber,large and small particle balls,the temporary plugging pressure at the fracture entrance can reach 20 MPa.When the particle size is larger than the fracture width,it can quickly hold up high temporary plugging pressure,and when the particle size is a little smaller than the fracture width,it can hold up the higher temporary plugging pressure after many times of plugging.When the particle size is much smaller than the fracture width,the dense plugging layer cannot be formed.The expanded particle ball can not form a dense plugging layer alone,but can be used in combination with a rigid particle ball to realize temporary plugging.Provides recommended temporary plugging agent combination and concentration under different fracture widths by analyzing and optimizing experimental results.The indoor optimal design is extended to the field.Temporary plugging agent has good stability and degradation under formation conditions.This study provides theoretical basis and data optimization method for temporary plugging steering fracturing in carbonate reservoir of Tahe oilfield,which can provide some reference for field construction.