A Study on the Effect of Heat Injection of Heavy Oil on the Temperature of Shallow Formations

Abstract In 2023, two wells in the NB 35-2 field had not yet begun to inject heat, and the temperatures in the 0-400m depth region of the formation were significantly higher than the values of the normal ground temperature gradient. Numerical simulation studies are carried out in order to investigate the reasons for the shallow formation temperature anomalies and to clarify the impact of heat injection wells on the surrounding area. Finite element numerical simulations were analyzed based on the thermal parameters of nitrogen, casing, cement ring and formation according to the actual well distribution. Numerical simulations of formation temperature changes in NB 35-2 due to production, steam stimulation were carried out. The simulation results show that: (1) the injection of nitrogen during the thermal extraction operation has a good thermal insulation effect, which can seal most of the heat in the tubing and casing annulus. (2) High fluid temperature in the two production wells is the primary cause of high shallow formation temperatures in NB 35-2. (3) In the extreme case, even if the insulated tubing is not working, there is a 3-5 day response time to treat the steam throughput well accordingly before it affects neighboring wells.