笼统注水对调整井钻井安全的影响

Effect of commingled water injection on the drilling safety of adjustment well

霍宏博

HUO Hongbo

中海石油(中国）有限公司天津分公司 海洋石油高效开发国家重点实验室

CNOOC Tianjin Company, Tianjin 300459, China State Key Laboratory of Offshore Oil Exploitation, Tianjin 300459, China

调整井是老油田稳产、提高采收率的重要手段，但长期注水导致地层压力紊乱使调整井钻井过程中井涌、溢流经常发生。以渤海某油田为例，通过建立油藏模型，采用数值模拟方法对垂向上存在渗透率差异的相邻两层进行笼统注水开发模拟，分析注水井注水和停注过程对调整井区域地层压力随时间的变化规律。研究结果表明：渗透率差异地层笼统注水使两层间始终存在压差，停注后一段时间内压差不会消失且足以导致钻井期间井涌发生，这是导致调整井钻井过程中多种复杂发生的重要因素。针对研究结果，提出调整井钻井前运用数值模拟方法对笼统注水开发存在层间渗透率差异区域进行压力预测的方法，并提出精细注水及调整井钻井时注水井停注时间的建议，以期对水驱老油田调整井钻井安全提供参考。

Adjustment well is one important technology for stable production and enhanced oil recovery (EOR) of old oil fields, but long-term water injection disturbs the reservoir pressure, leading to frequent well kick and overflow during the drilling of adjustment well. In this paper, a certain oilfield in the area of Bohai Sea was taken as an example. After a reservoir model was established, the commingled water injection in two adjacent layers whose permeability is vertically contrast was simulated by means of the numerical simulation method and the variation laws of reservoir pressure over the time in the area of adjustment well in the process of water injection and injection suspension of water injection wells were analyzed. It is indicated that the important factor leading to various complex situations during the drilling of adjustment well is that commingled water injection in the reservoirs with permeability contrast always keeps the pressure difference between two layers, which will not disappear and is still high enough to lead to well kick in the process of drilling after the injection is suspended for a while. According to the research results, it is recommended to adopt the numerical simulation method to predict the pressure of the commingled water injection areas with permeability contrast between layers before the drilling of adjustment well. And in addition, the suggestions on injection suspension time of water injection well during the drilling of adjustment well and fine water injection are proposed so as to provide the reference for the safe drilling of adjustment wells in old water flooding oilfields.

10.13639/j.odpt.2018.04.004