桥式同心井下恒流分层注水技术

Downhole Constant-Flow Stratified Water Injection Technology with Concentric Bridge

杨玲智 周志平 杨海恩 姬振宁

YANG Lingzhi ZHOU Zhiping YANG Haien JI Zhenning

中国石油长庆油田分公司油气工艺研究院, 陕西西安 710018 低渗透油气田勘探开发国家工程实验室, 陕西西安 710018

Oil & Gas Technology Research Institute, PetroChina Changqing Oilfield Company, Xi’an, Shaanxi, 710018, China National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Xi’an, Shaanxi, 710018, China

低渗透油藏分层注水合格率受压力波动等因素影响下降快，针对这一问题，设计了井下小体积水嘴自调节机构，将其集成于桥式同心井下恒流分层配水器，以缓解压力波动导致的分层注水量不稳定问题。基于伯努利方程，在理论分析及室内试验的基础上，设计了水嘴自调节机构，以达到井下小流量分层恒流注水目的。室内试验可知，自调节机构可在注入压力0.2～1.5 MPa范围内实现调节。采用水嘴自调节机构形成的桥式同心井下恒流分层注水技术，已在长庆油田低渗透油藏应用40余井次，实现了注入压力上升1.5 MPa以内不需人工干预、自动调节分层注水量至配注合格。长庆油田现场应用表明，桥式同心井下恒流分层注水技术可将6个月后分层注水合格率由常规分层注水的43.4%提高至75.0%，可将测调频次由常规分层注水的4次/年优化为2次/年，并延长分层注井测调周期，单井作业费用降低2.6万元/年。桥式同心井下恒流分层注水技术，为低渗透油藏精细注水开发提供了更高效的分层注水手段。

In view of the problem that downhole pressure fluctuations cause the qualified rate of stratified water injection to drop rapidly in low permeability reservoirs, a downhole small-volume water nozzle was designed with a self-adjusting mechanism. It was then integrated into the downhole constant-flow stratified water distributor using a concentric bridge, which would minimize pressure fluctuation-triggered stratified flow variations. On the basis of the Bernoulli principle, with theoretical analysis and laboratory experiment, a self-adjusting mechanism was designed to achieve the stratified and constant flow water injection with small flow rate. According to laboratory experiments, the self-adjusting mechanism can be adjusted within an injection pressure range of 0.2−1.5 MPa. Adopting the water nozzle mechanism, the downhole constant-flow stratified water injection technology with concentric bridge has been applied in more than 40 wells in the low permeability reservoirs of Changqing Oilfield. It is possible to achieve an increase of injection pressure rise by 1.5 MPa without manual intervention, and the stratified flow adjusted automatically until the injection is qualified. The field application in Changqing Oilfield showed that the technology could increase the qualified rate of stratified water injection from 43.4% to 75.0% within 6 months and reduce the testing and adjusting frequency from 4 times to 2 times per year. It can also prolong the testing and adjusting period of the involved wells so that the annual operation expenses for a single well can be reduced by 26 000 yuan.The stratified water injection technology proposed has provided an efficient stratified water injection method for fine water injection development in low permeability reservoirs.

国家科技重大专项“低渗-超低渗油藏提高储量动用关键技术”（编号：2017ZX05013-005）、中国石油与天然气股份公司重大科技专项“长庆油田5000万吨持续高效稳产关键技术研究与应用”之课题10“低渗油藏控水稳油工艺技术研究与试验”（编号：2016E-0510）联合资助

https://doi.org/10.11911/syztjs.2022051