二氧化碳驱特低渗油藏的封窜体系性能评价

Performance Evaluation of Channeling Blockage System for Ultra-low Permeability Oil Reservoirs with CO_2 Flooding

为了封堵特低渗油藏CO2驱过程中形成的窜流通道,选用常温常压下为液态的正丁胺作为封窜剂进行实验研究。正丁胺在油藏条件下能与CO2反应生成固体碳酸盐,且具有较高的强度,能够封堵CO2窜流通道。动态评价实验表明:加入乙醇保护段塞后,正丁胺的注入压力低于1.5 MPa,能满足特低渗油藏的注入要求;在渗透率级差为4.3的非均质岩心封窜实验中,注入正丁胺能提高低渗层采收率18%以上,说明正丁胺具有封堵高渗层启动低渗层的能力。实验结果表明,用正丁胺封堵气窜通道能为提高CO2驱特低渗油藏的开发效果提供一种新思路。

To block the channelling paths formed during CO2 flooding in ultra-low permeability oil reservoirs,liquid n-butylamine used as channeling blocker at normal temperature and normal atmosphere was studied by experiment. Under oil reservoir conditions,it can react with CO2 to produce high strength solid carbonate,which can block the CO2 channelling paths. It is indicated from the dynamic evaluation experiment that after alcohol slug is added for protection,the injection pressure of n-butylamine is lower than1. 5 MPa,meeting the injection requirement of ultra-low permeability oil reservoirs; in the channeling blockage experiment made in a heterogeneous core with a permeability grade difference of 4. 3,injection of n-butylamine increased the recovery factor of the low permeability formation by over 18%,demonstrating n-butylamine can block high permeability zones and initiate production from low permeability zones. It is shown from the experimental results that blocking gas channeling paths by use of n-butylamine provides a new approach for the enhancement of CO2 flooding effect in ultra-low permeability oil reservoirs.