水平井+CO_(2)吞吐改善中低渗稠油油藏开发效果机制解析——以大港油田刘官庄埕隆1601区块为例

Mechanism analysis of horizontal well+CO_(2)huff and puff to improve the development effect in medium and low permeability heavy oil reservoirs—A case from Liu Guan-zhuang Chenglong 1601 Block in Dagang Oilfield as an example

大港油田刘官庄埕隆1601区块特稠油油藏由于受原油粘度大、渗透率低、油层厚度薄、出砂及地面环境复杂等苛刻条件的制约,多年来常规的开采技术无法实现动用,为此开展了“水平井+CO_(2)吞吐”技术研究及矿场试验。利用室内实验及数值模拟手段,开展增油机制研究及注采参数优化,结果表明CO_(2)与稠油在非混相状态下混溶后,稠油粘度由16800 mPa·s下降至69 mPa·s,降粘率达99.6%,原油启动压力梯度由19.1 MPa/m降低至0.2 MPa/m,储层绝对渗透率提高了约41.86%,有效提高了稠油的流动性能;优化后的合理注采参数为:单位水平段注入强度3.5~5.5 t/m,单位水平段注入速度0.5~0.6 t/(m·d),闷井时间为25~35 d,单位水平段产液强度为0.075~0.125 m3/(m·d),采用“抽油机+液力反馈泵+电加热杆”及水力喷射泵两种注采一体化工艺。矿场“水平井+CO_(2)吞吐”技术试验证实,单井单轮次增油1000~2000 t,最高增油达4000 t以上,换油率2.0~4.5 t/t,技术和经济效果显著,证实了该技术的可靠实用性,为中低渗稠油油藏的有效开发提供了很好的借鉴。

Due to high oil viscosity,low permeability,thin reservoir formation,sand production,complex ground conditions,etc.,Liu Guan-zhuang Chenglong 1601 Block in Dagang Oilfield,which is a heavy oil reservoir,cannot be developed effectively through conditional development technology.Therefore,horizontal well+CO_(2)huff and puff technology was proposed to solve this problem.And the experimental researches and the field test were conducted.Through laboratory experiments and numerical simulations,the mechanisms of enhanced oil recovery were studied and the injection-production parameters were optimized.The results showed that,after CO_(2)was dissolved in the heavy oil,the viscosity of the oil decreased from 16800 mPa·s to 69 mPa·s,and the viscosity reduction rate was 99.6%;the threshold pressure gradient of the oil dropped from 19.1 MPa/m to 0.2 MPa/m.The absolute permeability increased by about 41.86%.Therefore,the heavy oil was more flowability.The optimal injected CO_(2)mass per unit length was between 3.5 and 5.5 t/m,the optimal CO_(2)injection rate per unit length was between 0.5 and 0.6 t/(m·d),the optimal shut in period was between 25 and 35 days,the optimal liquid production rate per day per unit length was between 0.075 and 0.125 m3/(m·d).Two kinds of integrated injection and production string,namely,the combination of oil pumping unit,hydraulic feedback pump and electric heating rod,hydraulic jet pump were employed.The horizontal well+CO_(2)huff and puff technology was carried out in field test,and significant technical and economic effects were achieved,which proved the reliability and practicality of this technology.A single round of CO_(2)huff and puff process obtained an oil increase of 1000~2000 tons,with the maximum oil increase of more than 4,000 tons.The oil production per mass CO_(2)was over 1.72 t/t.This technology provides a good reference for the economic exploration and development in the same type of oil reservoir.