天然气工业2024，Vol.44Issue(3)：10-19,10.DOI:10.3787/j.issn.1000-0976.2024.03.002
CO2快速吞吐提高页岩油采收率现场试验
Field tests and effect of CO2 rapid huff-n-puff to enhance shale oil recovery
摘要
Abstract
The technology of CO2 huff-n-puff for enhancing shale oil recovery is still in an exploratory stage.There are some technical challenges,such as unclear mechanism of interaction between CO2 and shale reservoirs/fluids,immature numerical simulation techniques,and absence of large-scale injection-production and low-cost recovery processes.A shale oil well in the second section of the Funing Formation of the Paleogene in the Qintong Depression of the Subei Basin was taken as a case of study.To figure out the dominant mechanism of CO2 huff-n-puff for enhancing shale oil recovery,this paper conducts an experiment on water-rock reaction with supercritical CO2 to investigate the dissolution of shale minerals at high temperature and pressure and its impacts on porosity and permeability.Then,the constant-mass expansion(CME)and minimum miscibility pressure(MMP)tests with CO2 injection are carried out to evaluate the changes in physical properties of crude oil at high pressure after CO2 injection into overpressured reservoirs.On this basis,multi-factor numerical simulation is conducted to optimize the injection parameters.Finally,a CO2 thermodynamics and fluid dynamics data template is established to optimize the surface process.The proposed technology is verified through field tests.The results show that the water-rock reaction with CO2 is dominated by the dissolution of carbonate minerals,and partial dissolution of felsic minerals,forming medium and large pores.By injecting appropriate volume of CO2 into formation oil,the intermediate hydrocarbon components of the crude oil are extracted significantly,allowing the viscosity of crude oil to decrease from 5.151 mPa·s to 1.250 mPa·s.Moreover,CO2 first extracts the light hydrocarbon components,and then the heavy hydrocarbons with the production time.Based on the compositional numerical model of mixed media(artificial fractures and natural fractures),the parameters of huff and puff in a single well are optimized with the injection rate being 1.7×104t,the injection velocity being 500-600 t/d,and the soaking time being 50 days.The surface process of side heating at low pressure for CO2 huff and puff achieves an accurate temperature control with the support of the multi-parameter model of surface process for CO2 injection,so that the problems such as freezing/blocking of injection pipes and brittle failure of donwhole tubing and casing at low temperature can be avoided.When the concentration of CO2 in produced gas is greater than 80％,the gas phase recovery and direct injection process is adopted to reduce the cost of produced gas recovery to CNY104/t.It is concluded that the technology of CO2 rapid huff and puff effectively enhances the recovery of shale oil.The relevant understanding on mechanism and techniques can provide reference and guidance for shale oil development by huff-n-puff.关键词
页岩油/注CO2/水岩反应/机理/混合介质组分数模/快速吞吐/地面工艺/现场试验Key words
Shale oil/CO2 injection/Water-rock reaction/Mechanism/Compositional numerical modeling of mixed media/Rapid huff-n-puff/Surface process/Field test分类
能源科技引用本文复制引用
姚红生,高玉巧,郑永旺,邱伟生,龚月,钱洋慧..CO2快速吞吐提高页岩油采收率现场试验[J].天然气工业,2024,44(3):10-19,10.基金项目
江苏省重大科技示范项目"苏北地区二十万吨级CCUS重大科技示范工程"(编号:BE2022603)、中国石化科技部项目"苏北高陡构造带页岩油直井有效开发关键技术与示范"(编号:P23151)、中国石化科技部项目"苏北CCUS-EOR一体化技术研究"(编号:P21107). （编号:BE2022603）
