缝洞型碳酸盐岩油藏酸压效果预测理论研究

THE THEORETICAL STUDY ON THE ACID FRACTURING EFFECT FORECASTING FOR FRACTURED-VUGGY CARBONATE RESERVOIRS

酸压技术是确保碳酸盐岩储层投产、增产的主要工艺技术。由于裂缝和溶洞发育,加之缝洞的定量识别精度低,缝洞型碳酸盐岩储层酸压效果预测难度大,是研究人员重点关注但却一直未能解决的难题,在一定程度上制约了酸压效果预测与酸压优化设计技术的发展。研究了缝洞型碳酸盐岩储层酸压效果的数值模拟理论,考虑的流体渗流介质包括:酸压裂缝、天然微裂缝、天然大裂缝、溶洞和基质。将大裂缝与基质的物质交换在微裂缝系统中加以描述,并将溶洞分为3类,建立了含第3类溶洞介质的天然大裂缝+溶洞+基质+酸压裂缝的多重介质、多组分流体渗流的压后产量数值模拟模型。编制了缝洞型油藏酸压单井生产动态的模拟器,实现了缝洞型油藏压后产量数值模拟,模拟了酸压裂缝、溶洞、天然大裂缝等对酸压井产量的影响。结果表明:溶洞和大裂缝对酸压井的产量具有重要影响,不同类型的溶洞对酸压后产量影响存在差异。

Acid fracturing is one of the main technologies to ensure and increase the production of carbonate reservoir.However,due to the growth of fissures and cavities,and the lack of precision of quantificational identification of them,it is quite difficult to predict the effectiveness of acid fracturing of the fractured-cavernous carbonate reservoirs.This is an issue that researchers have been paying much attention to but not solved.This to some extent restricts the development of effective prediction and optimal design of acid fracturing.The numerical simulation theory of acid fracturing effectiveness of fractured-cavernous carbonate reservoir is studied,in which several fluid seepage media are considered:artificial fractures,natural fissures,natural macro fractures,cavities,and matrix.Material exchange between macro fractures and matrix is described in micro fracture system and the cavities are divided into three types,and the numerical simulation model of post-stimulation production for the seepage of multi-media which contains the third type of cavity media such as:natural fissures,cavities,matrix,and artificial fractures is established.A simulator is programmed to simulate the production performance of an individual well in carbonate reservoirs,and the numerical simulation of post-fracturing production for fractured-cavernous carbonate reservoirs is realized and the effects of acid fractures,cavities and natural macrofractures on acid-fractured well production are simulated.The results show that cavities and macrofractures have significant effect on acid-fractured well production,and the effects of different types of cavities on post-stimulated production differ a lot.