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A real-time and reliable prediction method for the onset of a steam breakthrough in heavy oil wells is proposed by integrating deep learning algorithms with dynamic data from the wells. To address the issues such as frequent fluctuations and high noise level in single indicator data, and inability to accurately characterize the steam breakthrough time, a set of indicator parameters is constructed based on the actual injection and production data of the oilfield, effectively representing the formation time of the steam channel. These parameters are combined with the variation coefficient-G1 hybrid cross-weighting method to fuse into a comprehensive breakthrough identification curve of steam channeling. On this basis, suitable time series data are selected as input features using the similarity measurement method based on standard mutual information, with the corresponding breakthrough identification curve as the output time series for constructing the learning samples. A sequence-to-sequence deep learning framework is used to establish a prediction model for steam breakthrough time, and the effectiveness and superiority of the model are verified by the actual predictions and comparison with the traditional machine learning methods. This method simulates the mapping relationship between the characteristics of injection production time series and the identification curve of steam channeling in a data-driven way, which can effectively improve the efficiency and accuracy of steam channeling time prediction, and has certain guiding significance for the intelligent early warning of steam channeling. [ABSTRACT FROM AUTHOR]

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]

To understand the production decline law and accurately calculate the decline rates at ultra-high water cut stages, the calculation formula is deduced using the theory of oil-water two-phase flow and the reservoir engineering method based on the relative permeability curve that reflects the nature of oil-water two-phase seepage flow. Through comparison with the actual production data in the ultra-high water cut period, the accuracy of the formula is verified and the analysis on the influencing factors of the production decline rate is conducted. The results show that with the increase of parameters such as absolute permeability, pressure difference between injection well and production well and the change rate of oil relative permeability, the production decline rate increases almost linearly. With the increase of row distance, the production decline rate decreases. The effects of absolute permeability, pressure difference between injection well and production well, and the change rate of oil relative permeability on the production decline rate are the same, while the row distance effect is the most significant. The research results indicate that the proposed formula can precisely calculate the production decline rate at the ultra-high water cut stage, and this production decline rate follows an exponential law. [ABSTRACT FROM AUTHOR]