Optimization of Gel Flooding during the High Water Cut Stage in a Conglomerate Reservoir of the Xinjiang A Oilfield

Abstract

Influenced by water injection, a dominant flow channel is easily formed in the high water cut stage of a conglomerate reservoir, resulting in the inefficient or ineffective circulation of the injected water. With gel flooding as one of the effective development methods to solve the above problems, its parameter optimization determines its final development effect, which still faces great challenges. A new optimization method for gel flooding is proposed in this paper. Firstly, the gel flooding parameters were obtained through physical experiments; then, an experimental model of gel flooding was established according to the target reservoir, and parameter sensitivity analysis was carried out. Next, a history matching of the gel flooding experiment was carried out. Finally, history matching of the target reservoir was also carried out, and a gel flooding scheme was designed and optimized to determine the best parameters. The experimental results showed that the gelation time was 4 h and the gel viscosity was 6332 mPa·s; the breakthrough pressure, resistance factor (RF), and residual resistance factor (RRF) all decreased with the increase in permeability. The gel had a good profile control ability and improved oil recovery by 16.40%. The numerical simulation results illustrated that the porosity of the high permeability layer (HPL) had the greatest impact on the cumulative oil production (COP) of the HPL, and the maximum polymer adsorption value of the HPL had the largest influence on the COP of the low permeability layer (LPL) and the water cut of both layers. Benefiting from parameter sensitivity analysis, history matching of the gel flooding experiment and a conglomerate reservoir in the Xinjiang A Oilfield with less time consumed and good quality was obtained. The optimization results of gel flooding during the high water cut stage in a conglomerate reservoir of the Xinjiang A Oilfield were as follows: the gel injection volume, injection rate, and polymer concentration were 2000 m3, 50 m3/d, and 2500 mg/L, respectively. It was predicted that the water cut would decrease by 6.90% and the oil recovery would increase by 2.44% in two years. This paper not only provides a more scientific and efficient optimization method for gel flooding in conglomerate reservoirs but also has important significance for improving the oil recovery of conglomerate reservoirs.

Study on Water-Soluble Phenolic Resin Gels for High-Temperature and High-Salinity Oil Reservoir

“…This is related to the structure of the copolymer. The crosslinking mechanism of the gel is the polycondensation of phenolic resin and amide group in polymer chains [ 1 ]. As the copolymer’s AMPS content rises, the amide group content correspondingly reduces, resulting in a longer crosslinking time and weaker gel strength.…”

“…The problem of high water cut in oilfield development needs to be solved urgently, as it has the potential to reduce the utilization efficiency of injected water. A large amount of injected water flows through the high permeability layer, resulting in premature water emergence in oilfield development and a low sweep efficiency of the injected water [ 1 ]. To solve the above problems, common method is to inject selective plugging agents into high-permeability channels such as fractures [ 2 , 3 ].…”

Preparation and Performance Evaluation of Temperature-Resistant and Salt-Resistant Gels

“…Currently, there is a growing emphasis on the exploration and extraction of global petroleum reserves, particularly in high-temperature and high-salt reservoirs. However, these reservoirs are prone to developing cracks and high-permeability channels in the mining process, resulting in increased water production [1]. The heterogeneity of hightemperature and high-salinity reservoirs is pronounced.…”

Water Management and Oil Recovery Improvement Performance of High-Strength Preformed Particle Gels in Fractured Conglomerate Reservoirs

“…Currently, commonly used conformance control techniques to improve oil recovery include mechanical and chemical methods. , Chemical conformance control methods are widely used due to their convenient construction and low cost. , These methods involve injecting chemicals into the formation to adjust the water injection profile in the waterflood swept zone by the effect of either adsorption, retention, or plugging efficiency. , They can divert chase injection water toward high residual oil zones that have not been swept. − These chemicals mainly include in situ cross-linked polymer gels, particle gels, foam, etc., which have been evaluated in the laboratory and applied in the field in Xinjiang’s conglomerate reservoirs. − However, their conformance control effect has become very limited after many years of waterflooding in the field. Thus, it is necessary to select chemical systems with a higher strength to plug high-conductivity channels such as fractures.…”