As the driving energy to deal with the decrease of interlayer pressure caused by continuous oil production, the layered water injection technology has the characteristics of inhibiting the decrease of oil production and slowing down the increase of oil/gas ratio. In engineering, water injection technology is often used to improve the properties of crude oil, such as excessive viscosity, weak liquidity, and depleted storage, to avoid the formation of dead oil. Injecting appropriate amount of water into different production horizons can effectively maintain the formation water injection pressure, improve the sustainable development speed of the oilfield, ensure the oil production and effectively control the production cost. It is of great value to petroleum engineering and has been widely concerned by the industrial and academic circles at home and abroad. With the continuous development of oilfields over the years, most oilfields have become high-water-cut oilfields. Through the existing layered water injection technology, there are defects such as high labor cost, low operating efficiency, and long commissioning cycle. The ratio of water injection cost to constant increase gradually decreases, and the technical shortcomings become more and more obvious, which is difficult to meet production needs. It is urgent to study and optimize water injection technology scheme to meet oilfield production and technology iteration. In recent years, electronic technology, communication technology, automatic control technology, and other advanced production technology applied to geological exploration, logging technology fields such as engineering, oilfield development is towards integration and intelligent direction, which makes the advanced control and real-time communication intelligent power precision, and the layered water injection technology is possible. This paper summarizes the development history and status quo of oil recovery stratified water injection technology at home and abroad and points out that there are technical bottlenecks and development limitations in the development of water injection technology at present. Focusing on the current hot spots of intelligent oil recovery stratified water injection technology, the advantages and disadvantages of various intelligent water injection technology are compared and analyzed. It provides a certain theoretical reference value for the theoretical research and engineering application of intelligent stratified water injection technology to the equipment design and production of oilfield production and oil recovery technology research institutes and technology and equipment manufacturers.
Hydraulic fracturing, as an oil-water well stimulation and injection technology, is particularly important in the production and stimulation of low-permeability oil and gas fields, and the performance of the fracturing fluid directly affects the success of the fracturing operation. Compared with traditional water-based fracturing fluids, clean fracturing fluids have the advantages of strong sand-carrying ability and easy gel breaking with no residue. Aiming at the problem of poor temperature resistance and shear resistance of the clean fracturing fluid, based on previous research, this paper selects a high-temperature-resistant clean fracturing fluid system and evaluates the performance of the system. The research results show that the system has better rheological properties, better sand-carrying performance, shorter gel-breaking time, and less damage to the reservoir.
The engineering quality of rock mass is a key factor to evaluate the long-term stability and safety of high-level radioactive waste (HLW) geological disposal engineering and is also the important basis for disposal site selection. Traditional rock mass quality classification methods, such as RMR and Q , can meet underground engineering but still should be studied further for the site evaluation in the HLW disposal engineering. In this study, rock mass structure rating (RMSG) was proposed based on the quantitative control index of rock mass structure which was from the rock mass quality classification methods. Based on the statistical results of rock mass structure, the relationship between the number of RMSG and the modified RMR ( F RMR ) and Q ( F Q ) was established, China, as a case study. Results from this study show that RMSG is linearly related to F RMR and negatively exponential to F Q . The research results can solve the evaluation of rock mass quality for HLW geological disposal engineering, and the addition of more engineering examples over time will enable further verification.
In the past, the extreme value standardization of indicators, the traditional weighting method, and the multifactor comprehensive model of land intensive use inevitably linearly correlate the evaluation indicators with the evaluation objects, ignoring the direction differences of different indicators in different intervals. At the same time, these methods are also difficult to meet the change of evaluation index weight value with land use type, and cannot adapt to the actual situation of land use environment level and dynamic change. Considering the objectivity of nonlinear correlation moderate index and weight assignment, based on the standardization of quadratic function index and entropy assignment, this paper studies the intensive and dynamic use of land in development zones by different regions to improve the realistic fit of the evaluation model. The results show that the overall level of land intensive use in Chongqing center district and western Chongqing is better than that in northeast Chongqing and southeast Chongqing, roughly showing the state of “high in west and low in east.”
As a rock mass with shallow burial, high temperature, and large-scale development, the study of its mechanical and seepage characteristics plays an important role in the efficient development of geothermal energy. With the development of geothermal energy in China, a breakthrough has been made in the exploration of dry-hot rocks, and the realization of efficient development of dry-hot rocks has become the focus of attention. Systematic research on rock mechanics and seepage characteristics of dry-hot rocks has become a key research topic. Granite is the most typical dry-hot rock. In this paper, granite in the Qinghai area is selected as the research object, and experiments on physical characteristics, mechanical parameters, and seepage characteristics of granite are carried out to study the effects of different depths and temperatures on mechanical parameters and seepage characteristics of granite. The results show that the physical parameters of granite in Qinghai do not change obviously with the increase of depth, and granite has the characteristics of low water absorption and low porosity. At the same time, the parameters of water absorption and porosity at different depths are close, and the dispersion is small, so the rocks are very dense. The rocks have relatively high P-wave velocity and low S-wave velocity, and the elastic wave velocity changes little at different depths. With the increase of confining pressure, the strength of granite rock increases. Under different confining pressures, the rock shows brittle failure characteristics after the peak stress. According to Hoek–Brown and Mohr–Coulomb strength curves, the strength value is 173.52 MPa. After high temperature treatment, a complex fracture network is formed in the granite. With the increase of temperature, the permeability and porosity of the granite increase continuously, and 500°C is the temperature threshold. When the temperature is lower than 300°C and the stress is less than 30 MPa, the granite has negative Poisson’s ratio, and the permeability and effective stress of dry-hot rocks are piecewise linear functions. The research results provide theoretical guidance for fracturing of dry-hot rocks and exploitation of geothermal energy.
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