Oil Distribution Research Articles

Molecular Insights into the Control Mechanism of the Solid-Liquid Interface Interaction on Shale Oil Occurrence: Grand Canonical Monte Carlo and Molecular Dynamics Simulations Investigation.

The strong solid-liquid interaction leads to the complicated occurrence characteristics of shale oil. However, the solid-liquid interface interaction and its controls of the occurrence state of shale oil are poorly understood on the molecular scale. In this work, the adsorption behavior and occurrence state of shale oil in pores of organic/inorganic matter under reservoir conditions were investigated by using grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations. The adsorption potential energy and interaction energy were quantitatively evaluated, and the control mechanism of the oil-rock interaction on shale oil occurrence was explained. Results show that the density distribution of shale oil is not uniform under the confined space. Multiple layers of adsorption of n-octane occur in graphene pores. The number of adsorbed layers is mainly affected by pore size. With the increasing temperature and pore size, the adsorption site shifts from the high-energy to low-energy site and the solid-liquid interaction weakens. The effect of pressure on the occurrence state can be ignored due to capillary condensation. Minerals and oil chemical compositions also affect the oil-rock interaction and occurrence state. The adsorption intensity of minerals to n-octane decreases in the order graphene > montmorillonite > quartz. Competitive adsorption occurs among oil components. The adsorption order of oil components in graphene is asphaltenes > resin > nonhydrocarbon compound > aromatic hydrocarbons > saturated hydrocarbons. Asphaltenes preferentially adsorb on the surface of organic matter and occupy most of the adsorption surface, while saturated hydrocarbons mainly adsorb on the surface of heavy components or distribute in the pore center. The molecular structure of hydrocarbons also affects the adsorption characteristics. The long-chain hydrocarbons preferentially adsorb on the surface more than short-chain hydrocarbons. The straight-chain hydrocarbons preferentially adsorb more than the branched-chain hydrocarbons. This study provides the microscopic interaction between shale oil and minerals and explores the effect of the control mechanism of the oil-rock interfacial interaction on the occurrence state at the molecular level.

Remaining Oil Distribution and Enhanced Oil Recovery Mechanisms Through Multi-Well Water and Gas Injection in Weathered Crust Reservoirs

Weathered crust karst reservoirs with intricately interconnected fractures and caves are common but challenging enhanced oil recovery (EOR) targets. This paper investigated the remaining oil distribution rules, formation mechanisms, and EOR methods through physical experiments on acrylic models resembling the geological features of weathered crust reservoirs. Acrylic models with precision dimensions and morphologies were fabricated using laser etching technology. By comparing experiments under different cave filling modes and production well locations, it was shown that a higher cave filling extent led to poorer bottom water flooding recovery due to stronger flow resistance but slower rising water cut owing to continued production from the filling medium. Multi-well water and gas injection achieved higher incremental oil recovery by alternating injection–production arrangements to establish new displacement channels and change drive energy. Gas injection recovered more attic remaining oil from upper cave regions, while subsequent water injection helped wash the residual oil in the filling medium. The findings reveal the significant effects of fracture cave morphological configuration and connectivity on remaining oil distribution. This study provides new insights and guidance for EOR design optimization catering to the unique features of weathered crust karst fractured vuggy reservoirs.

A Study on the Residual Oil Distribution in Tight Reservoirs Based on a 3D Pore Structure Model

A tight reservoir is characterized by low porosity and permeability as well as a complex pore structure, resulting in low oil recovery efficiency. Understanding the micro-scale distribution of residual oil is of great significance for improving oil production and water flooding recovery rates. In this study, a 3D pore structure model of tight sandstone was established using CT scanning to characterize the residual oil distribution after water flooding. The effects of displacement methods and wettability on residual oil distribution at the micro-scale were then studied and discussed. Moreover, increasing the displacement rate has little effect on the distribution area and dominant seepage channels. Microscopic residual oil is classified into five discontinuous phases according to the oil–water–pore–throat contact relationship. The microscopic residual oil exhibits characteristics of being dispersed overall but locally concentrated. Under water-wet conditions, the injected water tends to strip the oil phase along the pore walls. Under oil-wet conditions, the pore walls have an improved adsorption capacity for the oil phase, resulting in a large amount of porous and membranous residual oil retained in the pores, which leads to a decrease in the overall recovery rate.

Optimization of Development Strategies and Injection-Production Parameters in a Fractured-Vuggy Carbonate Reservoir by Considering the Effect of Karst Patterns: Taking C Oilfield in the Tarim Basin as an Example

The spatial structural characteristics of fractured-vuggy units vary greatly in different karst patterns, which significantly influence the study of remaining oil distribution patterns in ultra-deep fractured-vuggy reservoirs and the determination of the most efficient development strategies. However, few numerical simulation studies have focused on improving water and gas injection in fractured-vuggy reservoirs by considering the effect of karst patterns. By taking a typical fractured-vuggy reservoir in C oilfield in Tarim Basin, China as an example, the development dynamic characteristics of eight typical fractured-vuggy units in three different karst patterns are analyzed, and based on the newly proposed numerical simulation method of fluid vertical equilibrium, the residual oil reservoir distribution in different karst pattern fractured-vuggy units are studied, and the effects of fracture-vuggy karst patterns on the development characteristics, on the remaining oil morphology pattern, on the development strategies, and on the injection-production parameters are explored. This study shows that for different karst patterns fractured-vuggy units, the complexity of spatial structure, reserve scale, and oil-water relationship aggravates the heterogeneity of reservoirs and results in substantial differences in the development of dynamic patterns. In the northern facing karst fractured-vuggy units, there are two main types of remaining oil: well-spacing type and local-blocking type, and the reasonable development strategies are affected by reservoir morphology and the connectivity of structure patterns. Attic-type remaining oil mainly occurs in platform margin overlay and fault-controlled karst fractured-vuggy units. In the southern fault-controlled karst area, the remaining oil is mostly found along the upper part, and periodic gas injection or N2 huff-n-puff is recommended with priority for potential tapping. The fractured-vuggy karst patterns show a significant influence on the optimal level of injection-production parameters for improving the development of gas injection development strategies. The ideas of improving water injection and gas injection for fracture-vuggy reservoirs proposed in this paper also provide a good reference to further improve water control and increase oil production in other similar carbonate reservoirs.

Study on Improving Recovery of Highly Heterogeneous Reservoirs by Unsteady Water Injection Technology

Unstable water injection can effectively improve the recovery ratio of reservoirs with strong heterogeneity. However, the oil displacement mechanism and the determination method of unstable water injection parameters still need to be clarified, especially for complex fracture reservoirs, which greatly restrict the popularization and development of unstable water injection technology. This paper studies unstable water injection technology in highly heterogeneous reservoirs from the core and reservoir scales, utilizing many displacement experiments and numerical simulations. The differences in oil displacement efficiency, remaining oil distribution, pressure field, and streamlines between continuous water injection and unstable water injection are compared and evaluated. Five flow stages of unstable injection and production are precisely divided, and the microscopic and macroscopic displacement mechanism is clarified. A numerical model of two injection wells and one production is established to determine the best time to implement unstable water injection technology. Based on the principle of pressure superposition, the expression of pressure field distribution between injection and production well in each period of unstable water injection is analytically solved. This formula has provided a new development parameter optimization method aiming at the maximum pressure fluctuation range and optimized the development technology parameters in the water injection process. The results show that precise control injection and production parameters can expand water swept volume, effectively improve the degree of reserve utilization, and improve the recovery of complex reservoirs by 3–7%, which provides a reliable basis for the practical implementation of unstable water injection technology.

A Study on Performance of Al-Si alloy Bearing with SAE20W40 as Lubricants in Constant Load and Varying Speed Condition

Abstract: Bearing is used to carry radial loads of transmitting members in motion is called as journal bearing. Journal bearings are considered as essential components of all the rotating machinery. Various researchers carried out analysis particularly on copper based alloys published information related to Aluminium-Silicon alloy as a bearing material and relevant information are not available. So in the present work it has been selected to carry out the study on performance of the Aluminium-Silicon alloy bearing by considering the SAE20W40 grade lubricating oils as lubricating mediums and study has been carried out to find out the maximum pressure distribution by using a journal bearing test rig. The Al-Si alloy as test bearing and test lubricating oils SAE20W40 is run at different loads and speeds either by constant load and varying speed conditions (Example; 150N, 300rpm). It is made to run for 1hour to take maximum pressure value at angular rotation of 180̊. Sensor mounted on the bellow of the housing which gives the pressure readings and the data are transferred to the WINDOWS DUCOM 2010 software, extract condition of the bearings and gives the pressure distribution graphs as shown outcomes. In the results found by the graphs at all operating conditions of constant load and varying speed. The maximum pressure distribution of SAE20W40 grade oil is 1744kPa at 500 rpm. It can be conclude that the load carrying capacity and frictional force which acts on the journal and bearing material is safer, where frictional force decrease when speed increases.

Complex Calculation Method of Air Cooling Systems of Gas Turbines and Lubrication Systems of Bearing Assemblies

The article is devoted to the improvement of the calculation methodology of air cooling systems and oil supply systems of gas turbine bearings by reasoned selection of boundary conditions and the structure of a homogeneous flow, which allows in the process of developing the support nodes of the engine rotor to determine the influence of geometric and mode parameters on the distribution of oil and the coefficient of heat transfer to the walls of the chamber, which forms an oil cavity. During the simulation, special attention is paid to the physics of the process, since a coolant with different properties can move in the channels of the cooling system, namely: liquid (oil), gas (air), or an air-oil mixture. If there is a two-phase substance in the channel, then the properties depend not only on the amount of gas content, but also on the orientation and geometric characteristics of the channels through which it flows.

Wear resistance and lubricity of the spiral oil distribution profile of the valve guide sleeves of an internal combustion engine

Valve guides are crucial for maintaining the correct alignment, positioning, and clearance of the valve stem as it moves in the cylinder head. When the guides are heavily worn, the engine begins to consume oil and the valve mechanism becomes noisy. Reliable lubrication of the inner surface of the guide bushing ensures the wear resistance of the valve-guide pair. This work proposes a special tool and technology for obtaining an oil-retaining profile on the inner surface of the valve guide, which increases the oil capacity of the surface, and therefore improves the lubrication conditions in the valve-guide friction pair. A gas labyrinth seal is created in the connection, which prevents oil from entering the combustion chamber. The surface of the bushing bore is strengthened due to the sealing of the surface. The results of wear tests of guide bushings with spiral oil-retaining grooves confirmed their effectiveness in terms of wear resistance. The wear rate of the bushings with grooves for the entire time range of the tests is on average 20% less than the wear rate of the bushings without grooves

Experimental Study on the Mechanism of Enhanced Imbibition with Different Types of Surfactants in Low-Permeability Glutenite Reservoirs.

Due to the complex physical properties of low-permeability glutenite reservoirs, the oil recovery rate with conventional development is low. Surfactants are effective additives for enhanced oil recovery (EOR) due to their good ability of wettability alteration and interfacial tension (IFT) reduction, but the reason why imbibition efficiencies vary with different types of surfactants and the mechanism of enhanced imbibition in the glutenite reservoirs is not clear. In this study, the imbibition efficiency and recovery of surfactants including the nonionic, anionic, and cationic surfactants as well as nanofluids were evaluated and compared with produced water (PW) using low-permeability glutenite core samples from the Lower Urho Formation in the Mahu oil field. Experiments of IFT, wettability, emulsification, and imbibition at high-temperature and high-pressure were conducted to reveal the underlying EOR mechanisms of different types of surfactants. The distribution and utilization of oil in different pores during the imbibition process were characterized by a combined method of mercury intrusion and nuclear magnetic resonance (NMR). The main controlling factors of surfactant-enhanced imbibition in glutenite reservoirs were clarified. The results demonstrate that the micropores and mesopores contribute most to imbibition recovery in low-permeability glutenite reservoirs. The anionic surfactant KPS exhibits a good capacity of reducing IFT, wettability alteration, and oil emulsification with the highest oil recovery of 49.02%, 8.49% higher than PW. The nonionic surfactant OP-10 performs well on oil emulsification and wetting modification with imbibition recovery of 48.11%. This study sheds light on the selection of suitable surfactants for enhanced imbibition in low-permeability glutenite reservoirs and improves the understanding of oil production through enhanced imbibition.

Application of Resistance Ring Array Sensors for Oil–Water Two-Phase Flow Water Holdup Imaging in Horizontal Wells

Unconventional oil and gas reservoirs are frequently developed using inclined and horizontal wells, leading to intricate multiphase flow patterns due to spatial asymmetry surrounding the wellbore and gravitational differentiation effects. Through the examination of water holdup imaging, the spatial arrangement of oil and water phases within the wellbore may be clearly depicted, yielding critical information for precisely assessing the ratios of oil and gas. This study employed No. 10 industrial white oil and tap water as fluid media, with measurements obtained using a resistive ring array tool (RAT) to evaluate its response properties over the wellbore cross-section. The data gathered throughout the trials were analyzed by two-dimensional interpolation imaging utilizing 2020 version MATLAB software. To enhance the analysis of water holdup distribution in the wellbore, three interpolation algorithms were utilized: Simple Linear Interpolation (SLI), Inverse Distance Weighting Interpolation (IDWI), and Ordinary Kriging Interpolation (OKI). The results indicated that RAT operates effectively in medium and low flow circumstances, correctly representing the real distribution of oil and water phases while yielding more dependable water holdup data. The SLI algorithm effectively delineates the oil-water interface during stratified flow of oil and water phases, rendering it the optimal algorithm for determining water holdup in standard flow patterns. Under DW/O&W and DO/W&W flow patterns, SLI continues to perform well; however, the accuracy of IDWI and OKI markedly enhances, with IDWI more effectively delineating the attributes of intricate mixed flow and more precisely representing the dynamic fluid distribution. Under DW/O and DO/W flow patterns, the OKI algorithm exhibits optimal performance in these intricate dispersed flow patterns. OKI more precisely represents the dynamic distribution of dispersed oil and water due to its capacity to simulate the spatial correlation of both phases, surpassing both SLI and IDWI.

IDENTIFIKASI BAHAYA DAN PENGENDALIAN RISIKO KECELAKAAN KERJA DALAM PROSES DISTRIBUSI MINYAK MENTAH

One type of work accident that often occurs is road transport accidents. The Ministry of Transportation shows a significant increase in the number of road transport accident victims from year to year. In 2022, the number of victims will reach 204,447 people, an increase of 33% compared to the previous year. During this period, 163,686 people recorded accident victims with minor injuries, 27,531 people died, and 12,230 people with serious injuries. This final assignment reviews identifying hazards and controlling the risk of work accidents in the crude oil distribution process at PT Sangkakala Niaga Energi in 2024. This research aims to identify potential hazards, analyze risk factors, and outline risk control measures. This type of research uses qualitative data research methods obtained from interviews, observations, and document analysis. From the results of the observation sheet, you can get an overview of the crude oil distribution process with 9 indicators and 73 statement items. The results of the observations identified 22 hazards and potential events in the crude oil distribution process. The Frequency Level (Possibility) and Severity Level (consequences) have various levels. There are 14 planned control actions that have been implemented, while there are 8 actions that do not include control actions. Researchers suggest that companies provide regular K3 training and disseminate knowledge about PPE in crude oil distribution work and provide sanctions for workers who violate company operational standards (SOP), can equip workers' facilities and provide action on hazards that have not received control measures so that safety programs and occupational health is going well

Reductive Depolymerization of Lignin to Aromatic Compounds over Promoted Nickel Catalysts in Sub‐ and Supercritical Methanol

AbstractThe use of γ‐Al2O3‐supported Ni catalysts promoted with either Cu or Fe was investigated for the reductive catalytic fractionation (RCF) of hybrid poplar in methanol at 200 and 250 °C. The effectiveness of lignin depolymerization was quantified in terms of the lignin oil production, the quantity and distribution of identifiable monomers present in the lignin oil, and the yield of residual solids. All of the Ni‐based catalysts tested provided improved yields of lignin oil and monomers, along with reduced char formation, relative to blank (sans catalyst) runs. The highest monomer yield of 51 % was obtained at 250 °C over a 20 wt.% Ni‐5 wt.% Cu/Al2O3 catalyst, the improved performance obtained through Cu promotion being attributed to the ability of Cu to facilitate NiO reduction, resulting in an increased amount of Ni0 on the catalyst surface and, consequently, improved hydrogenation activity. The main monomers formed were propanol‐, propyl‐ and propenyl‐substituted guaiacol and syringol, the S/G ratio of the products corresponding closely to that in the native lignin.

Effect of Reservoir Heterogeneity on Polymer-Surfactant Binary Chemical Flooding Efficiency in Conglomerate Reservoirs.

Reservoir heterogeneity significantly affects reservoir flooding efficiency and the formation and distribution of residual oil. As an effective method for enhancing recovery, polymer-surfactant (SP) flooding has a complex mechanism of action in inhomogeneous reservoirs. In this study, the effect of reservoir heterogeneity on the SP drive was investigated by designing core parallel flooding experiments combined with NMR and CT scanning techniques, taking conglomerate reservoirs in a Xinjiang oilfield as the research object. The experimental results show that inter-layer heterogeneity significantly affects water flooding efficiency and SP driving in low-permeability cores-the larger the permeability difference is, the more obvious the effect is-while it has almost no effect on high-permeability cores. The limited recovery enhancement in low-permeability cores is mainly due to the small percentage of contributing pores. When the permeability difference undergoes an extreme increase, the polymer molecular weight is biased towards higher values; when the polymer molecular weight is fixed, the recovery enhancement of low-permeability cores may be comparable to that of high-permeability cores when the permeability difference is extremely small. However, the recovery enhancement of the former is smaller than that of the latter when the permeability difference is extremely large. Due to intra-layer heterogeneity, there is a serious fingering phenomenon in the flooding stage, while in the SP flooding stage, recovery enhancement is most significant in the 5-20 μm pore range. This study provides an important geological basis for the rational development of a chemical flooding programme.

Improvement of the properties of essential oil-starch film with whey protein isolated fibril and sodium caseinate

Essential oil-starch films are important bioactive films, but their properties are not good enough and need improved. In this work, sodium caseinate (CAS) was utilized to improve the distribution and release of Cinnamon essential oils (CEO), and whey protein isolate fibril (WPIF) of different loadings (0 %, 4 %, 8 % and 12 %, w/w) in starch basis was added to enhance the mechanical properties of starch films. Physical, mechanical, thermal, structural, antibacterial properties, and essential oil release in the films were investigated. CAS-CEO nanoemulsion (190.7±9.4 nm) promoted the compatibility between starch and WPIF. The addition of CAS-CEO nanoemulsion and WPIF synergistically enhanced the tensile strength, stiffness, crystallinity and antibacterial effects, reduced the water vapor permeability of films, and especially delayed the release of essential oil from the films. The starch film composited with CAS-CEO nanoemulsion and appropriate loading of WPIF (8 %) significantly improved the film properties, but the addition of 12 % WPIF disrupted the properties, which might be attributed to the excessive aggregation of WPIF. The work provided useful information for improving the properties of CEO films via adding the emulsifier of CAS and the texture booster of WPIF, which could help to improve the film properties containing oil-soluble bioactive agents.

Experimental and Theoretical Determination of Relative Permeability Together with Microscopic Remaining Oil Distribution Based on Pore-Throat Structures

Experimental and Theoretical Determination of Relative Permeability Together with Microscopic Remaining Oil Distribution Based on Pore-Throat Structures

Characteristics and Genesis of Heavy Oil in Shallow and Thin Layers in Chepaizi Area, Xinjiang, China

The Neoproterozoic Shawan Formation in the Chepaizi area is recognized for its significant heavy oil resources. Investigating the underlying causes and mechanisms of heavy oil changes in accordance with the specific characteristics of the reservoir is crucial for future exploration and development. The distribution of heavy oil in the Pai 612 block was identified to present a combination of shallow and thin deposits, high porosity, high permeability, and elevated water content. The physicochemical properties of the crude oil included a complex composition, high density, high viscosity, substantial gel content, and notable oxidation-biodegradation potential. The oxidation and biodegradation of crude oil during transportation played the critical roles in the formation of heavy oil. As cru3de oil was transported upward, the formation temperature decreased, resulting in increased viscosity. An excess of water could initially increase and subsequently decrease heavy oil viscosity, while groundwater in the reservoir contained various chemicals that interacted with colloids and asphaltenes, further increasing the viscosity. During the formation of the early heavy oil reservoir, the light oil was unable to dissolve and transport the high-molecular-weight asphaltene component, leading to the high resin content in the heavy oil of the Pai 612 block.

Microalgae-loaded SPI-based monodisperse emulsions prepared by PREMIX membrane emulsification: Effect of pH and HHP on droplet size and droplet size distribution

Emulsions containing Chlorella vulgaris (CV), Arthrospira platensis (AP), Soy Protein Isolate (SPI) powders, or their combination as emulsifiers were prepared at 2 or 3 % protein concentration by intramembrane PREMIX membrane emulsification. Then, the effect of pH (3.5, no-change, 10) and HHP (0.1 and 200 MPa) on mean droplet size (MDS) and size distribution (SPAN) of canola oil in water emulsions was assessed. Emulsions with individual emulsifiers showed undesired MDS and SPAN at pH 3.5, while plant-microalgae emulsions presented better MDS and SPAN values at all pHs. Emulsions at pH 10 had better MDS and SPAN values. AP emulsion prepared at 3 % concentrations showed the highest improvement in MDS and SPAN when 200 MPa were applied. HHP had a positive effect when applied to CV-SPI and AP-SPI at 2 % protein concentration. However, an adverse effect was observed at 3 % protein concentration. Microalgae and plant emulsions with interesting properties can be obtained by pH and HHP treatment.

Structural Characteristics of the Fault Zone and Fault-Controlled Hydrocarbon Accumulation in the Chenghai Area of Dagang Offshore.

The Chenghai area is a secondary structural unit within the Qikou sag of the Bohai Bay Basin, located in the southern part of the Dagang offshore area, known for its abundant oil and gas resources. Influenced by multiple episodes of tectonic activity, the Chenghai area exhibits a highly developed fault system, which significantly impacts oil and gas exploration in the region. To investigate the structural characteristics of fault zones in the Chenghai area and their petroleum geological significance, this study builds upon previous research by utilizing oilfield drilling data and relevant seismic information. Through methods such as fault growth index analysis, structural evolution history, and examination of typical oil and gas reservoir profiles, a detailed structural analysis of fault-controlled hydrocarbon accumulation in this petroleum region was conducted. The results reveal three types of fault classifications in the study area: basal-controlled continuously active faults, buried reactivated segmented growth-connected faults, and late-stage continuously active isolated growth faults. The structural evolution is divided into four stages: the pre-Paleogene basement formation stage, the Rifting I stage of intense extensional deformation, the Rifting II stage of extensional stress reversal and intense deformation, and the post-Eocene weak extensional deformation-stable burial stage. The fault-controlled accumulation models include three types: fault-guided longitudinal accumulation, lateral sealing fault masking accumulation, and far-source step-like fault-guided accumulation. The formation of fault zones and fault-controlled oil and gas reservoirs in the Chenghai area is primarily influenced by inherited development faults, which determine the overall macroscopic distribution of oil and gas. The formation of oil and gas reservoirs occurred relatively late, with a general trend of decreased fault activity during this period, facilitating the effective accumulation and sealing of hydrocarbons.

Study on the Microscopic Distribution Pattern of Residual Oil and Exploitation Methods Based on a Digital Pore Network Model.

With the persistent rise in global energy demand, the efficient extraction of petroleum resources has become an urgent and critical issue. Polymer flooding technology, widely employed for enhancing crude oil recovery, still lacks an in-depth understanding of the distribution of residual oil within the microscopic pore structure and the associated displacement mechanisms. To address this, a digital pore network model was established based on mercury intrusion experimental data, and pore structure visualization was achieved through 3Dmax software, simulating the oil displacement process under various polymer concentrations, molecular weights, and interfacial tension conditions. The findings reveal that moderately increasing the polymer concentration (from 1000 [mg/L] to 2000 [mg/L]) improves the recovery factor during polymer flooding by approximately 1.45%, effectively emulsifying larger masses of residual oil and reducing the proportion of throats with high oil saturation. However, when the concentration exceeds 2500 [mg/L], the dispersion of residual oil is hindered, and the enhancement in displacement efficiency becomes marginal. Increasing the molecular weight from 12 million to 16 million and subsequently to 24 million elevates the recovery factor by approximately 1.07% and 1.37%, respectively, reducing clustered residual oil while increasing columnar residual oil; high molecular weight polymers exhibit a more significant effect on channels with high oil saturation. Lowering the interfacial tension (from 30 [mN/m] to 0.005 [mN/m]) markedly enhances the binary flooding recovery factor, with the overall recovery reaching 71.72%, effectively reducing the residual oil within pores of high oil saturation. The study concludes that adjusting polymer concentration, molecular weight, and interfacial tension can optimize the microscopic distribution of residual oil, thereby enhancing oil displacement efficiency and providing a scientific foundation for further improving oilfield recovery and achieving efficient reservoir development.

Research on Oil and Gas-Bearing Zone Prediction and Identification Based on the SVD–K-Means Algorithm—A Case Study of the WZ6-1 Oil-Bearing Structure in the Beibu Gulf Basin, South China Sea

The WZ6-1 oil-bearing structure in the Beibu Gulf Basin of the South China Sea has well-developed faults with significant variations in fault sealing capacity, resulting in a complex and highly variable distribution of oil, gas, and water, and limited understanding of hydrocarbon accumulation patterns. Traditional methods, such as single seismic attributes and linear fusion of multiple seismic attributes, have proven ineffective in identifying and predicting oil and gas-bearing areas in this region, leading to five unsuccessful wells. Through comprehensive analysis of drilled wells and seismic data, six types of horizon seismic attributes were selected. A novel approach for predicting oil-bearing zones was proposed, employing SVD–K-means nonlinear clustering for multiple seismic attribute fusion. The application results indicate: ① Singular value decomposition (SVD) technology not only reduces the correlation redundancy among seismic attribute data variables, but enables data dimensionality reduction and noise suppression, decreasing ambiguity in prediction results and enhancing reliability. ② The K-means nonlinear clustering method facilitates the nonlinear fusion of multiple seismic attribute parameters, effectively uncovering the nonlinear features of the underlying relationship between seismic attributes and reservoir oil-bearing characteristics, thereby amplifying the hydrocarbon information within the seismic attribute variables. ③ Compared to K-means, SVD–K-means demonstrates superior performance across all metrics, with an 18.4% increase in the SC coefficient, a 57.8% increase in the CH index, and a 24.7% improvement in the DB index. ④ The results of oil-bearing zone prediction using the SVD–K-means algorithm align well with the drilling outcomes in the study area and correspond to the geological patterns of hydrocarbon enrichment in this region. This has been confirmed by the high-yield industrial oil flow obtained from the newly drilled WZ6-1-A3 well. The SVD–K-means algorithm for predicting oil and gas-bearing zones provides a new approach for predicting hydrocarbon-rich areas in complex fault block structures with limited drilling and poor-quality seismic data.