The Application Of Acid Fracturing Fluid For Calcareous Sandstone Reservoir In Shengli Oilfield

Due to the complex lithology,the gray matter content of Bin 105 block reservoir,located in Binnan district in Shengli oil field,varies drastically:the content of clastic rock such as quartz and feldspar are rich in structural high part,while the content of carbonate rock and shale are rich in structural low part.The carbonate content varies from 50%to60%,and the shale content is about 20%in Bin 105 block reservoir.The research shows the heterogeneity of Bin 105 block reservoir is intense.The average permeability is between 0.1 millidarcy and 0.5 millidarcy.The permeability differential is 3.2.The average porosity is between 14.6%and 21.7%.The average porosity is 17.5%.In complicated geology of Bin 105 block reservoir,the expected stimulated target is hard to be satisfied while using the conventional acid fracturing technology.Therefore,a set of stimulated technology system suitable for calcareous sandstone reservoirs needs to be explored,aiming at improving the adaptation and efficiency of the stimulated technology.This paper analyzes the geological characteristics of Bin 105 block reservoir.A series of laboratory experiments have been performed.Firstly,the concentration evaluation and optimization of densifier,crosslinking agent and conditioner of acid fracturing fluid experiments were conducted.Secondly,the evaluation and optimization of corrosion inhibitor,clay stabilizer,demulsifier,cleanup additive and other additives were completed.And then,the rheological properties evaluation experiments on acid fracturing fluid such as shear resistance,temperature resistance,gel breaking and proppant carrier were carried out.Finally,the retention rate of ceramsite and quartz proppant both in the fresh acid and in the residual acid were tested.In conclusion,the calcareous sandstone reservoir of Bin 105 block acid fracturing fluid formulation system with sand were formed:0.8%densifier+15%HCl+0.5%crosslinking agent+0.5%conditioner+3.0%FL-A+1.2%KCl+0.5%KMS+1.0%BF-5+0.5%DL-8.Throughout the optimization design of the single well Bin 105-17,the fracture morphology of surface cross-linked acid fracturing both with sand and without sand,and gelled acid multistage acid fracturing+closed acidizing technology without sand under the flow rate of 3m~3/min and 4m~3/min were simulated.As a result,gelled acid multistage acid+closed acid is the recommended optimal scheme,and the results of on-site construction were analyzed after the accomplishment of acid fracturing treatments.It turned out that the design scheme was an operational success,and a set of reservoir reconstruction technology system suitable for calcareous sandstone was developed successfully.