超深层低渗透稠油CO2增溶降黏体系研发与应用

Development and application of CO2 solubilizing and viscosity reducing system for ultra-deep and low-permeability heavy oil reservoirs

目前采用CO2吞吐开采超深层低渗透稠油油藏无法达到经济产能,即使使用降黏剂和CO2辅助热采开发也存在降黏效果差、单井产能低和油藏开发难度大等问题。通过使用分子体系设计和实验验证,对CO2增溶降黏剂进行研发,利用化学剂本身降黏功能和增强CO2溶解原油的能力,将化学降黏与CO2开采两种稠油开采技术进行有机结合,达到降低稠油黏度以及增强稠油流动性的目的。研制的增溶降黏剂可使CO2溶解度增大7倍,降黏率高达99.2%,有效解决了超深层低渗透稠油降黏范围小的难题。矿场应用结果表明,试验井周期平均日产油量达到原日产油量的2.5倍以上,取得了良好的效果。

CO2 puff and huff cannot achieve commercial oil productivity for the ultra-deep and low-permeability heavy oil reservoirs at present. The thermal recovery assisted by viscosity reducer and CO2 faces the issues of poor performance of oil viscosity reduction,low productivity of single well and large difficulty of reservoir development. CO2 solubilizing and viscosity reducing system is developed according to molecular system design and experimental verification.In this technology,chemical viscosity reduction and CO2 recovery for the heavy oil are combined to reduce oil viscosity and enhance heavy oil mobility through viscosity reduction effect of chemicals itself and the enhanced ability of CO2 dissolved in oil. The developed CO2 solubilizing and viscosity reducing system can increase the solubility of CO2 by 7 times,and the viscosity reduction ratio is up to 99.2%,which effectively solves the problem of narrow range of oil viscosity reduction for the ultra-deep and low-permeability heavy oil reservoirs. The field application results show that the average daily oil production of the test well is higher than 2.5 times of the original daily oil production,which achieved a good performance.