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The productivity of low-permeability reservoirs is affected by multiple factors. After the development of water injection by pressure drive, it will also be affected by factors such as construction, resulting in large differences in the productivity of different oil wells. According to reservoir engineering knowledge, the factors affecting the productivity of pressure drive water injection development are preliminarily determined. The conceptual model of pressure drive water injection development of low permeability reservoir is established by numerical simulation method. Combined with orthogonal design, the main control factors of pressure drive water injection development productivity are determined. The main control factors include injection production well spacing, water injection volume of pressure drive measures, water content before pressure drive, porosity, and quantitative analysis of the main control factors. Through correct analysis and evaluation of these factors, it provides guiding significance for the productivity prediction of pressure drive water injection development in low permeability reservoirs and the optimization of pressure drive water injection scheme.

In view of the practical problems faced by the CO2 sequestration in aquifers, this paper considers the influence of injection rate, water production rate, and other factors on CO2 injection amount, residual sequestration amount, dissolution sequestration amount, and pressure evolution under the constraint of cap rock breakthrough pressure is studied by using a numerical simulation method, and the sequestration potential is evaluated. The results show that: (1) Water production measures can improve CO2 injection, dissolution sequestration, and residual sequestration. (2) Low ratio of vertical permeability to horizontal permeability is conducive to the security and stability of CO2 sequestration in the long term. The research content provides support for the evaluation of CO2 saline aquifer sequestration potential and field practice.

Traditional machine learning methods are difficult to accurately forecast oil production when development measures change. A method of oil reservoir production prediction based on normalized mutual information and a long short-term memory-based sequence-to-sequence model (Seq2Seq-LSTM) was proposed to forecast reservoir production considering the influence of liquid production and well spacing density. First, the marine sandstone reservoirs in the Y basin were taken as the research object to establish the sample database. Then, the feature selection was carried out according to the normalized mutual information, and liquid production, production time, equivalent well spacing density, fluidity and original formation pressure were determined as input features. Finally, a Seq2Seq-LSTM model was established to forecast reservoir production by learning the interaction from multiple samples and multiple sequences, and mining the relationship between oil production and features. The research showed that the model has a high accuracy of production prediction and can forecast the change of production when the liquid production and well spacing density change, which can provide scientific recommendations to help the oilfield develop and adjust efficiently. [ABSTRACT FROM AUTHOR]

Predicting the productivity of fractured five-spot patterns in low permeability reservoirs at high water cut stages has an important significance for the development and optimization of reservoirs. Taking the reservoir heterogeneity and uneven distribution of the remaining oil into consideration, a novel method for predicting the transient productivity of fractured five-spot patterns in low permeability reservoirs at high water cut stages is proposed by using element analysis, the flow tube integration method, and the mass conservation principle. This new method is validated by comparing with actual production data from the field and the results of a numerical simulation. Also, the effects of related parameters on transient productivity are analyzed. The results show that increasing fracture length, pressure difference and reservoir permeability correspond to an increasing productivity. The research provides theoretical support for the development and optimization of fractured five-spot patterns at the high water cut stage.

To further improve the evaluation accuracy of CO2 storage potential in saline layer, a new method for calculating the theoretical tectonic CO2 storage volume was proposed based on the material balance equation of CO2 tectonic storage process and the accurate calculation of underground volume of CO2 storage. As found in the results, the error of theoretical tectonic CO2 storage volume calculated by the new method was smaller than that of area method and volume method, which was only about 10%; the new method can predict the theoretical tectonic storage volume under both CO2 pressurized and pressure-retaining underground storage conditions; both theoretical tectonic CO2 storage volume and formation pressure showed a trend of increasing with the increase of injection time or injection-production ratio. The new method is of great significance to the study of CO2 tectonic storage and real-time dynamic control. [ABSTRACT FROM AUTHOR]

Aiming at the distribution characteristics of remaining oil in high water cut reservoirs, based on the theory of reservoir engineering and considering economic factors, a partitioning method for the abundance of remaining recoverable reserves in ultra high water cut reservoirs was established and the high-potential and low-potential area of the whole reservoir were obtained. The high-speed and low-speed flow area of the oil reservoir were divided according to the reservoir seepage conditions. Comprehensive consideration of the two zoning results further determined the development strategies for different regions. The application results in actual blocks show that comprehensive consideration of the high-potential and low-potential area of the reservoir as well as the low-speed and high-speed flow area of formation seepage can be effectively coupled with development strategies, which is useful for adjusting and developing strategies for ultra high water cut reservoirs. [ABSTRACT FROM AUTHOR]

To achieve the purpose of reducing water production, increasing oil production, cutting down cost and increasing efficiency without additional investment and cost, the injection-production coupling technique is adopted to change the underground pressure field and strengthen the weakly affected area. Currently, the studies on the mechanism of injection-production coupling and the optimization of injection-production parameters are mainly carried out by using mathematical models and material models at home and abroad. However, there are few studies on the utilization range and utilization degree of residual oil. In this paper, a numerical simulation model is established based on the actual fault block of Xianhe. Through the analysis of pressure gradient and pressure change, the utilization range and utilization degree of residual are obtained. Besides, by analyzing the influence of change of influencing factors on the development effect of injection-production coupling mode, the applicable conditions of injection-production coupling mode are given, which can provide theoretical ordnance for oil filled work. Results show that the operating range of residual oil under the condition of injection-production coupling is about 4 times that under the condition of stable water injection. In the fault reservoir water flooding development, the further the oil well is away from the fault, the closer the water well is to fault, and the more suitable the injection-production coupling is. Borderless and bottomless water reservoir is more suitable for the development of injection-production coupling mode. The injection-production coupling method has good adaptability to inclined reservoirs. [ABSTRACT FROM AUTHOR]