Given the characteristics of unconventional oil and gas reservoirs，such as low porosity，low permeability，and well-developed natural fractures，this study systematically reviews the theoretical and application progress of the hydraulic fracturing technology. The full text revolves four core domains：First，it reviews the development history of hydraulic fracturing numerical simulation methods and explores the control mechanisms of cross-layer behaviors of fractures in vertical wells and balanced multi-cluster propagation of fractures in horizontal wells. Second，it analyzes the characteristics of fracturing operation curves and the formation mechanisms of screen-out，while highlighting real-time intelligent early warning technologies based on artificial intelligence. Third，it summarizes the evaluation methods for stimulated reservoir volume （SRV） and post-fracturing effectiveness based on instantaneous shut-in pressure decline analysis （G-function），micro-seismic data，and dynamic production data. Finally，it compares the application advantages of traditional empirical production decline models，modern numerical simulation，and machine learning in predicting production of oil and gas wells with complex fracture networks. This study intends to provide a solid theoretical foundation and reference for exploring fracturing mechanisms in complex reservoirs，optimizing operational designs，and improving the development efficiency of unconventional oil and gas. It also points out future development directions，including refined simulation of multi-field coupling，engineering adaptability of intelligent early warning，and precise dynamic characterization of SRV.

Volume fracturing is one of the key technologies for the efficient development of unconventional oil and gas resources. At present，volume fracturing has entered the stage with the core characteristics of multi-cluster，small cluster spacing，limited entry perforating，temporary plugging diversion，high injection rates and high-intensity proppant injection. Perforation erosion is serious in cases of high injection pressure，high injection rates and high sand concentrations. This leads to high likelihood of failure of temporary plugging and limited entry and consequently high difficulties in delivering spontaneous initiation and uniform propagation of fractures due to competitive fluid attraction among perforation clusters within one fracturing stage，which is practically restraining the safe and high-efficiency development of unconventional oil and gas. A global literature review of the studies on perforation erosion in both China and other countries is performed. The theoretical models of perforation erosion are summarized，and the research status of perforation erosion is analyzed. The causes of perforation erosion during large-scale propped fracturing are discussed，the factors affecting perforation erosion are identified，and the countermeasure strategies are proposed. Clarifying the main factors controlling perforation erosion and the corresponding laws and developing protective measures are of great engineering significance for the efficient development of unconventional hydrocarbon resources.

Proppant transport is a critical process that determines the conductivity of hydraulic fractures and thus，is of great significance for the efficient development of unconventional oil and gas reservoirs. This paper systematically reviews the progress in research on proppant transport，summarizes the advantages and limitations of three types of research methods，namely theoretical models，physical experiments，and numerical simulations，and reveals the multi-factor coupling effects of proppant characteristics，fracture morphology，operational parameters and reservoir environment are revealed. It is indicated that micronized proppants can enhance the filling rate of secondary fractures，but need to be combined with composite proppant injection processes to compensate for insufficient near-end support. In complex fractures，proppant distribution is considerably influenced by the flow splitting and rough fracture surface，requiring optimization through temporary plugging diversion and high-viscosity fracturing fluids. The integration of numerical simulations and machine learning techniques has significantly improved the prediction accuracy of complex fracture networks. Future research shall more focus on dynamic characterization of multi-scale fracture networks，long-term conductivity evaluation under high temperature and pressure，and the industrial application of intelligent fracturing technologies to facilitate controllable proppant placement and long-term conductivity and provide theoretical support for the efficient development of unconventional oil and gas resources.

Integral fracturing is one of the key technologies for the cost-effective development of unconventional reservoirs，which delivers one-time well placement，one-time fracture placement and synchronized initiation of production through batch drilling and batch fracturing. Optimization of well and fracture spacing is of great significance to improve the performance of integral reservoir stimulation. In this work，a typical block of the Mahu conglomerate reservoir is taken as an example to establish a three-dimensional geological model through the geology-engineering-integrated Petrel platform using well logs，mud logs and fracturing treatment parameters. Based on CMG，a numerical reservoir simulator，and logarithmic mesh refinement method，a hydraulic fracturing model of a four-well platform is constructed for production forecasting. Using the particle swarm optimization （PSO） and differential evolution （DE） algorithms，the well spacing and the fracture spacing of the four-well platform are optimized with the well group productivity as the objective function，which realizes the seven-dimensional synchronized parameter optimization. The optimized well group productivity is about 16.3% higher than that of the actual case. The optimized four-well platform presents a longer stable production duration and slower production decline. The optimized hydraulic fracturing treatment is found with a larger affected zone，further promoting the improvement of oil productivity. The findings of this work provide the fundamental model and methodology for optimizing the integral fracturing scheme of unconventional reservoirs.

The reservoirs at a block of Xinjiang Oilfield have the characteristics of high heterogeneity，and uneven natural bedding plane development and stress distribution. The vertical fracture propagation mode of such reservoirs with bedding planes under complex stresses has an impact on the layer-penetrating fracturing effect. Based on the finite element method and cohesive zone model，a three-dimensional fluid-solid fully coupled numerical model with bedding planes has been established. The vertical propagation patterns of hydraulic fractures under the influence of different stress conditions and bedding planes were studied. the layer-penetrating fracture propagation mode of reservoirs with beddings was also clarified，forming a prediction diagram of fracture penetrating patterns under complex stresses. The model’s simulation results are consistent with the published results of physical modeling experiments，validating the model’s reliability. The research results show that the smaller the vertical stresses，the easier the fractures activated along the bedding planes. When the vertical stresses are less than 18 MPa，the fractures propagate along the bedding planes. The greater the horizontal stress difference，the greater the barrier effect applied on the fractures by the bedding planes. When the horizontal stress difference is greater than 3 MPa，the fractures are more easily captured by the bedding planes and propagate along the bedding planes. The greater the tensile strength of the bedding planes，the more likely the fractures are to propagate through the bedding planes. The research results will provide theoretical guidance for layer-penetrating fracturing design of layered reservoirs.

Large-scale hydraulic fracturing is the essential technology for cost-effective and efficient development of tight sandy conglomerate reservoirs. Gravel parameters are considered the key factors that influence the hydraulic fracture geometry. The existence of gravels can make it even harder to complete fracturing stimulation. The complex fracture geometry，high tortuosity，and shorter supporting fracture length make it difficult to achieve the designed fracture conductivity. In this research，the continuous-discontinuous element method （CDEM） was applied to establish a 2D full fluid-solid coupling fracture propagation model to explore the influence of stress difference，gravel content，and flow rate on the fracture propagation geometry. The numerical simulation results show that：the multi-phase media hydraulic fracturing model based on the CDEM method can accurately simulate the overall fracture propagation geometry under the influence of gravel；the fractures will divert and generate a tortuous fracture when meeting high strength gravel；in reservoirs with high stress，hydraulic fractures tend to pass around the gravel and then divert to the direction of the maximum horizontal principal stress；in the presence of gravel，the fracture propagation will shape a high-pressure zone and generate more micro-fractures，thus increasing the stimulated reservoir volume. This study lays a theoretical basis for optimization of the fracturing design of conglomerate reservoirs.

Fracturing of infill horizontal wells is one of the effective ways to improve the recovery factor of shale oil and gas. However， practices show that the production of an infill well after fracturing is generally lower than that of the parent well， and the fracturing effect is limited. The nature lies in that the fracture propagation of an infill well communicates with the pressure depletion zone of the parent wells， which makes it difficult to produce the remaining inter-well oil and gas resources. This paper proposes that radial multilateral wells be used to control the fracture propagation of an infill horizontal well， so as to increase the contact area between fractures and untapped oil and gas areas and prevent fractures from entering the pressure depletion areas of the parent well， which is expected to be a solution to the engineering problem of infill wells with poor fracturing effect. Therefore， a fracture propagation model of radial multilateral wells is established with the complicated uneven inter-well stress fields taken into account. The influence pattern of the uneven stress fields in different production phases of the parent well as well as the parameters of radial multilateral wells on the propagation of fractures are studied， and the optimal azimuth angle of a lateral borehole is selected. The results show that radial multilateral wells can effectively control the propagation of fractures in those untapped areas in different production phases of the parent well. The feasibility of controlling the fracture propagation of an infill horizontal well with multi-lateral wells is validated. The angle between a lateral borehole and the infill horizontal well is the main controlling factor affecting the forms of fractures.

Tarim Basin is endowed with rich natural gas resources. For most gas wells，the wellhead pressure is ultra-high. Currently，a high-pressure gas gathering technology is applied to all these wells，with the gas gathering pressure greater than 10 MPa. The wellhead pressure-reducing technology by multi-stage throttling has not fully utilized the residual pressure resources. In addition，its matching electric heat tracing and anti-freeze addition technologies have increased the consumption of electricity and chemicals，resulting in a waste of residual pressure resources. Therefore，it is of great significance to conduct an analysis of the residual wellhead pressure resources in Tarim Oilfield and a discussion on their utilization options. In this paper，exergy analysis approach is applied to establishing a rational theoretical calculation model of pressure energy，so as to accurately calculate the amount of recoverable pressure energy resources at the wellheads of gas wells. Adhering to the principles of maximizing the recovery of residual wellhead pressure resources and ensuring the normal operation of existing gas gathering and processing system，such utilization options of residual pressure resources as electricity generation with residual pressure，natural gas liquefaction，separation of light hydrocarbons and electricity generation-ice making with residual pressure resources are put forward，and their key techniques，technical difficulties and supporting measures are analyzed to avoid a waste of residual pressure resources caused by the use of existing ways of throttling. These utilization options not only save energy，reduce discharge and increase the comprehensive utilization rate of energy resources，but also bring favorable economic benefits，providing theoretical basis for the comprehensive utilization of residual wellhead pressure resources in Tarim Oilfield