Performance evaluation of microemulsion acid for integrated acid fracturing in Middle Eastern carbonate reservoirs  

作　　者：WANG Yunjin ZHOU Fujian SU Hang LI Yuan YU Fuwei DONG Rencheng WANG Qing LI Junjian 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China [2]MOE Key Laboratory of Petroleum Engineering,China University of Petroleum,Beijing 102249,China [3]China National Oil and Gas Exploration and Development Corporation,Beijing 100034,China [4]PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China [5]University of Texas at Austin,Austin TX78712,USA

出　　处：《Petroleum Exploration and Development》2023年第5期1196-1205,共10页石油勘探与开发（英文版）

基　　金：Supported by the National Science and Technology Major Project(2017ZX05009-005-003);National Natural Science Foundation of China Funded General Project(52174045);Chinese Academy of Engineering Strategic Consulting Project(2018-XZ-09);China National Petroleum Corporation-China University of Petroleum(Beijing)Strategic Cooperation Science and Technology Project(ZLZX2020-01).

摘　　要：Considering the characteristics of carbonate reservoirs in the Middle East,a low-viscosity microemulsion acid that can be prepared on site and has an appropriate retardation ability was developed.It was compared with four conventional acid systems(hydrochloric acid,gelled acid,emulsified acid and surfactant acid)through experiments of rotating disk,multistage acid fracturing and core flooding with CT scanning.The micro-etching characteristics and conductivity of fracture surfaces were clarified,and the variation of saturation field during water invasion and flowback of spent acid and the recovery of oil phase relative permeability were quantitatively evaluated.The study shows that the addition of negatively charged agent to the oil core of microemulsion acid can enhance its adsorption capacity on the limestone surface and significantly reduce the H+mass transfer rate.Moreover,the negatively charged oil core is immiscible with the Ca^(2+)salt,so that the microemulsion acid can keep an overall structure not be damaged by Ca^(2+)salt generated during reaction,with adjustable adsorption capacity and stable microemulsion structure.With high vertical permeability along the fracture walls,the microemulsion acid can penetrate into deep fracture wall to form network etching,which helps greatly improve the permeability of reservoirs around the fractures and keep a high conductivity under a high closure pressure.The spent microemulsion acid is miscible with crude oil to form microemulsion.The microemulsion,oil and water are in a nearly miscible state,with basically no water block and low flowback resistance,the flowback of spent acid and the relative permeability of oil are recovered to a high degree.

关 键 词：Middle East carbonate microemulsion acid acid-rock reaction conductivity spent acid flowback permeability recovery 

分 类 号：R28[医药卫生—中药学]