抽油机井压差式套管气回收装置

A differential pressure casing gas recovery device for pumping wells

吕旭 侯宁 黎成 姚雪 程小波

LYU Xu HOU Ning LI Cheng YAO Xue CHENG Xiaobo

中国石油长庆油田分公司第一采油厂

No.1 Oil Production Plant, PetroChina Changqing Oilfield Company, Yan'an 716000, Shaanxi, China

长庆安塞油田为丘陵沟壑区低渗透油田，单井产量低，中低含水期生产气油比高。为了回收套压低于回压、井站高差大的油井套管气，降低冬季井组回压，研制了抽油机井压差式套管气回收装置。该装置通过套管单流阀与油管单流阀分别连通套管气管线和出油管线，在井口形成三通结构，具备压差集气、气侵集气和定压集气功能。当套压与回压差值小于井口油压波动差值时，实现压差集气；当套压低于井组回压时，利用气相流速越大爬坡管线压降越低的原理实现气侵集气；当套压持续超过回压时，实现定压集气。现场应用结果表明，该装置平均单井日回收套管气260 m³以上，冬季可降低回压0.6 MPa，集气和降回压效果显著。

The Changqing Ansai oilfield is a low-permeability oilfield in a hilly and gully region, with low well productivity and high produced gas-oil ratio in the low–medium water cut stage. In order to recover casing gas from producing wells with casing pressure lower than back pressure and large elevation differences between wells and stations, and reduce back pressure of well groups in winter, a differential pressure casing gas recovery device was developed for pumping wells. This device connects the casing gas line and the flow line through the casing check valve and the tubing check valve, respectively, forming a three-way structure at the wellhead to be capable of differential pressure-driven gas collection, invaded gas collection and constant-pressure gas collection. When the difference between casing pressure and back pressure is less than the fluctuation amplitude of the wellhead tubing pressure, the differential pressure gas collection is enabled. When the casing pressure is lower than the back pressure of the well group, the invaded gas collection is achieved, as the pressure drop of up-dip pipelines reduces with the increasing gas velocity. When the casing pressure is continuously above the back pressure, the constant pressure gas collection is performed. Field application results show that this device can recover more than 260 m/day of casing gas per well and reduce back pressure by 0.6 MPa in winter. The presented device delivers a remarkable performance of gas collection and back pressure reduction.

10.13639/j.odpt.2023.01.016