Study On Conductivity Of Acid Etching Fracture Of Multistage Alternating Injection Acid Fracturing

Yuanba Changxing district reservoir belongs to high temperature,atmospheric pressure,super-deep fracture-pore type carbonate reservoir.The effective distance can be short since the acid-rock reaction controlled by high reservoir temperature.Acid etching fracture conductivity decline rapidly lead to development severely affected.In addition,there are many uniform etching patterns on the crack wall,which leads to the rapid decrease of the conductivity of acid etching cracks,and the development is seriously affected.Multistage acid fracturing technology can effectively reduced the alternating injection reservoir temperature,delay the acid rock reaction rate,and thereby achieve deep penetrating reservoir,at the same time use the filter cake formation fracturing fluid,the acid corrosion fracture surface non-uniform etching,and make the acid corrosion fracture has higher effective flow conductivity.Because there is no angle adjustment from engineering practice the appropriate acid rock reaction time,acid concentration,acid injection displacement and different injection series of important parameters,such as study of the effect of acid fracturing modification alternating injection,resulting in the insufficient construction parameter design is fine.For accurate simulation of acid injection process,this article from pre-production and modification methods of analyzing test well data,using PKN model to simulate the crack,a general displacement field under the corresponding seam length and slit width change.Deduce the Reynolds number similarity criterion to complete the field displacement to the corresponding laboratory displacement transformation.In order to simulate the external conditions of the acid flow through the crack,the temperature field in the middle part of the crack is simulated by the finite element method to set the temperature of the laboratory experiment.Use the acid fracture etching device,considering the condition of single factor,the control of different acid rock reaction time,acid concentration,acid injection displacement and different acid etching rock plate pressure technology,with a laser scanner for etching the surface of the rock plate 3 d shape,through morphological analysis confirmed that according to Yuanba Chuangxi group of class ? reservoirs,optimum injection acid series for level 3,alternately contact time for 60 min of each level of acid rock,determine the acid injection displacement is 60 ml/min corresponding to the scene of the 5 m3/min,and eventually inject fresh acid concentration of 20%is the best conditions were determined.The simulation results are verified by using the acid-eroded fracture conductivity tester.The simulation results are applied to the optimization of the acid pressure construction scheme of single well,which has achieved good effect of improving the yield,and obtained great economic benefit.