Productivity Prediction Of Acid Fracturing Wells In Carbonate Reservoir Considering The Wormhole And Micro-fractures

Carbonate reservoirs usually contain heterogeneous natural fractures and they will have some influence on the distrbution of acid solution in acid fracturing.In the process of acid fracturing,the liquid pressure is higer than formation fracture pressure.While crushing the formation,the acid solution will also react with the minerals to produce some uneven etching grooves.The production and development of acid etched wormhole is decided by the non uniform etching of acid solution on the acid fracturing wall surface.On the other hand,the expansion of acid etching wormholes will have an important influence on the further flow of acid solution.Therefore,it is necessary to consider the influence of acid wormholes and micro fractures on the production of acid fracturing wells in carbonate reservoirs.This study based on the actual physical flow and chemical reaction process in the reservoir,combined with relevant statistical law to establish the geological model.On the basis of geological model,the fracture extension model and etching model of acid fracturing wall are studied.Considering the impact of wormhole and natural micro-fractures on the acid fracturing process.Finally,the productivity prediction of acid fracturing wells is carried out.In addition,the whole capacity prediction model is compiled as a practical software.The influence of acid fracturing length and width on the productivity prediction of acid fracturing wells is analyzed with the example wells.The main research of this paper is as follows:(1)Considering the characteristics that cluster distribution at the macro level and random distribution at the micro level of natural fractures.Combining the the non uniform distribution of reservoir physical parameters.The spatial correlation coefficient is introduced to establish the geophysical model.(2)Fracture extension model is established to simulate the etching morphology of acid fracturing wall.Optimization design of construction parameters based on field data.Furthermore,the influence of rock bedding on the etching morphology of acid fracturing wall is analyzed.(3)We focus on the wormhole and micro-fractures effect of acid filtration and acid fracturing extension on the process of acid fracturing.Oil production capacity of acid fracturing wells is predicted by oil water two phase flow model.The results of this study extend the scope of the previous production forecast.It is of great significance to improve the accuracy and effectiveness of the productivity prediction of acid fracturing wells in carbonate reservoirs.