Key Techniques For Improving The Length Of Acid Corrosion Cracks In Leikoupo Gas Reservoir In Western Sichuan

The key to carbonate rock reservoir stimulating is to create a long acid etching cracks in the acid pressure process in order to jioning more storage space.The properties of Leikoupo gas reservoir in western Sichuan are deep burial,high temperature and high n pressure which bring great challenges to increase the length of acid etching crack in the acid pressure process.Based on literature research,it is necessary to understand the factors affecting the crack length,the performance of the modified fluid and the adaptation process to improve the acid etching cracks length of the carbonate rock in Leikoupo gas reservoir.Keep the idea in mind,the theoretical analysis and a large number of PT software simulations,the geological characteristics of the acid-stimulating in the Leikoupo gas reservoir in western Sichuan are clearly defined.There were 10 main controlling factors to control the length of the fracturing which included three aspects:engineering geological characteristics,liquid type characteristics,main construction technology and parameters.Based on the simulation analysis of the main controlling factors affecting the length of the acid-etched fracturing,combined with the research on the acid pressure technology and field test of the marine gas reservoirs in the Northwest and Puguang gas fields,it is clear that the large-scale,large-displacement,multi-system alternately injects acid did work.After reviewing the liquid charaters and evaluation optimization experiments,the high-viscosity fracturing fluid system,gelling acid system and cross-linked acid system were confirmed because which meet the field application standards.Alternating injection process did better than single stage.The alternating injection technology lead to higher conductivity of the acid-etching cracks.The conductivity of the acid etching fractures at 30 MPa was higher than that of the cross-linked acid.Simulation experiment indicated,the conductivity of the rock plate can be increased.A suitable level of alternation can achieve a relatively good construction effect.The optimization result of the subsequent level is:the acid liquid increase rate is 29%and the pre-liquid increase rate is 22%.Through on-site pilot test,it do well that "multiple acids(gelling acid,cross-linked acid,closed acid)and fracturing fluid(water-reducing water)" are alternately injected into large-scale acid pressure process to improve the acid etching cracks of the Leikoupo gas reservoir in western Sichuan.