Oil Wettability Research Articles

From Nanotechnology to Oilfields: the Potential of Microemulsions and Nanoemulsions in Preflush Fluids for a Sustainable Alternative

Objective: The objective of this study is to contextualize the advancements in the application of micro- and nanoemulsions in preflush fluids within the oil industry. Theoretical Framework: The study draws upon concepts in nanotechnology and fluid dynamics, focusing on the role of preflush fluids in wellbore cleaning and rock wettability adjustment. Method: A bibliometric analysis and review of the literature were conducted. The bibliometric analysis included 145 keywords and 382 articles related to preflush fluids in the oil industry, published between 2003 and 2023. The data were analyzed and visualized using VOSviewer. Results and Discussion: The results revealed fluctuations in the number of publications on this topic over the years. The bibliometric review highlighted the evolution of preflush fluid formulations, particularly those involving micro- and nanoemulsion systems. These fluids demonstrated high oil solubilization capacity and wettability reversal, effectively addressing formation stability issues. Research Implications: The findings underscore the significance of micro- and nanoemulsion systems in enhancing the efficiency and environmental sustainability of preflush fluids used in oil extraction operations. Originality/Value: This study contributes to the literature by offering a comprehensive analysis of the advancements in preflush fluid formulations, emphasizing the sustainable potential of micro- and nanoemulsions in the oil industry.

Quality Evaluation of Flour and Crackers Made from Acha and Orange-Fleshed Sweet Potato Composite Flour Supplemented with Fermented Cowpea Flour

The present study aimed at evaluating the effects of supplementing 60% acha and 40% orange-fleshed sweet potato (OFSP) composite flour with 0, 10, 20, 30, 40 and 50% fermented cowpea flour on the functional properties of the flour blends and on the proximate composition, mineral content, antinutrients, and sensory characteristics of the crackers made from the blends. The 100% composite of acha and orange-fleshed sweet potato flours served as the control sample. The results obtained showed that all the parameters evaluated varied with the proportion of fermented cowpea flour supplementation. The bulk density increased significantly while the water absorption capacity, oil absorption capacity, pH, wettability, and gelatinization temperature decreased significantly with the increase in fermented cowpea flour supplementation. The moisture and carbohydrate content of the crackers progressively decreased from 8.83% - 8.08% and from 68.34% - 54.33% respectively with increase in cowpea flour supplementation. The ash, fibre, fat and protein contents of the crackers progressively increased from 1.90 - 2.43%, 0.40 – 0.70%, 14.46 – 18.45% and 6.07 – 16.01% respectively with increase in fermented cowpea flour supplementation. The potassium content of the crackers decreased from 87.51 – 68.66 mg/100g while the calcium, magnesium, iron and zinc contents of the crackers increased progressively from 59.16 - 96.61 mg/100g, 12.60 – 36.69 mg/100g, 0.62 – 0.78 mg/100g and 0.78 – 1.08 mg/100g respectively with increase in fermented cowpea flour supplementation. The oxalate and phytate contents of the crackers decreased progressively, while the tannin content increased with increasing fermentation of cowpea flour supplementation. It is evident from the study that acceptable crackers of high nutritional value could be produced from a composite of 60% acha and 40% orange-fleshed sweet potato flour supplemented with 30% fermented cowpea flour. This would increase the utilization of these locally grown crops and reduce wheat importation into the country.

One-step preparation of modified photothermal-driven melamine foam with gradient wettability for oil–water separation

One-step preparation of modified photothermal-driven melamine foam with gradient wettability for oil–water separation

Microscopic Mechanism of CO2 Displacement Oil in Different Pore Throat Radius Segments of Tight Sandstone Reservoirs.

The micropore structure of tight sandstone affects the efficiency of CO2 displacement of crude oil. As the pressure changes, the oil displacement efficiency (E d) in segments with different pore radii changes, and the asphaltene precipitation in the pores causes alterations in the pore structure and wettability, which constrain E d. Ten samples of tight sandstone from the Yanchang Formation in the Ordos Basin were selected for this study. A variety of methods, including X-ray diffraction (XRD), casting thin sections (CTS), scanning electron microscopy (SEM), high-pressure mercury intrusion (HPMI), CT scanning, and nuclear magnetic resonance (NMR) combined with CO2 displacement, were used to study the efficiency of crude oil utilization and the amount of asphaltene deposited at different pore-throat radii, and then the impacts of pressure, pore structure, and wettability changes on E d were discussed. The findings indicate that samples have three types: macropore-fine throats (MF), medium pore-tiny throats (MT), and small pore-microthroats (SM). The MT exhibits a favorable configuration. The pore-throat radius of each sample can be divided into two segments, namely, large pore segments (PL) and small pore segments (PS), and the PL has a significant E d. The E d of the MF-type PS is constrained by pressure. The E d of PL is significantly affected by the pressure sensitivity for the MT, while the E d of PL for the SM structure is more affected by pressure. Changes in wettability and the precipitation of asphaltene are the results of the reaction between crude oil and CO2. In the MF, asphaltene precipitates from the PL, while in the MT and SM, asphaltene precipitates both from the PL and PS. The amount of asphaltene precipitation strongly affects the E d in PS. The oil wettability increases more obviously with better pore-throat configurations. This study offers a reference and foundational understanding for evaluating CO2 displacement in tight sandstone reservoirs.

Flow unit classification and characterization with emphasis on the clustering methods: a case study in a highly heterogeneous carbonate reservoir, eastern margin of Dezful Embayment, SW Iran

Previous attempts to classify flow units in Iranian carbonate reservoirs, based on porosity and permeability, have faced challenges in correlating the rock's pore size distribution with the capillary pressure profile. The innovation of this study highlights the role of clustering techniques, such as Discrete Rock Type, Probability, Global Hydraulic Element, and Winland's Standard Chart in enhancing the reservoir's rock categorization. These techniques are integrated with established flow unit classification methods. They include Lucia, FZI, FZI*, Winland R35, and the improved stratigraphic modified Lorenz plot. The research accurately links diverse pore geometries to characteristic capillary pressure profiles, addressing heterogeneity in intricate reservoirs. The findings indicate that clustering methods can identify specific flow units, but do not significantly improve their classification. The effectiveness of these techniques varies depending on the flow unit classification method employed. For instance, probability-based methods yield surpassing results for low-porosity rocks when utilizing the FZI* approach. The discrete technique generates the highest number of flow unit classes but provides the worst result. Not all clustering techniques reveal discernible advantages when integrated with the FZI method. In the second part, the study creatively suggests that rock classification can be achieved by concurrently clustering irreducible water saturation (SWIR) and porosity in unsuccessful flow unit delineation cases. The SWIR log was estimated by establishing a smart correlation between porosity and SWIR in the pay zone, where water saturation and SWIR match. Then, the estimated saturation was dispersed throughout the reservoir. Subsequently, the neural network technique was employed to cluster and propagate the three finalized flow units. This methodology is an effective recommendation when conventional flow unit methods fail. The study also investigates influential factors causing the failure of flow unit classification methods, including pore geometry, oil wettability, and saturation in heterogeneous reservoirs.

Modification of a hybrid fluoro-surfactant containing double fluorocarbon chains on the carbonate and shale rocks for the wettability reduction of water and oil

An original hybrid fluoro-surfactant DHE with double fluorocarbon chains was synthesized. This surfactant aimed to reduce significantly the wettability of water and oil on the carbonate and shale rocks and adapt to the high salinities of the formation water. This could enhance the imbibition and injection of water in the matrix of carbonate reservoirs and the fracturing flowback in shale reservoirs. DHE showed good interface activities in salt-free and brine solutions, and remarkable water- and oil-wettability reduction on the two kinds of rocks. Moreover, its tolerant-NaCl concentrations were not below 80 g/L. The diameters of DHE mono-molecules were 1.5–4 nm and innumerable worm-like micelles were observed by TEM at the critical micelle concentration of 1.2 g/L in water. After being modified only using the 0.03 g/L DHE saline with 30 g/L NaCl for the carbonate rock, the surface energy was reduced substantially, so the primary water- and oil-wetting (θ: 43–50.6°) on the rock changed to nearly intermediate wetting (θ: 85.0−87.4°), which was the most ideal wetting state for oil and gas production in reservoirs. Moreover, the modifying effect of DHE on the rocks became stronger with the DHE and salt concentrations in the DHE brines. Therefore, it was found that the capillary pressure could be changed to zero using very small amounts of hybrid fluoro-surfactants such as DHE because the rocks could be altered to intermediate wetting for water and oil phases. Consequently, the oil recovery in the water-flooding of carbonate reservoirs and the fracturing flowback in shale reservoirs would be improved significantly.

ON DEVELOPMENT OF OIL FIELDS

Using a literature review, the article concludes that the displacement of oil by surfactants affects interrelated factors: by affecting the surface tension at the oil-water-rock interface, SAM adsorption occurs on the surface of pore channels, rock surface water and oil wetting changes, the oil layer is broken up and washed from the rock surface, the dispersion of oil in water stabilizes, the phase permeability of the porous medium changes, and finally, the forced displacement of oil by the water phase occurs. Keywords: gravity, elastic, capillary forces, adhesion, adsorption.

Amino‐modified banana nanocellulose aerogels with quick pH‐responsive switchable wettability for oil–water separation

AbstractWith the rapid development of the maritime industry, oily wastewater discharges and oil spills cause acute environmental challenges. Currently, cellulosic materials with switchable wettability have received increasing interest for oil–water separation. Moreover, work efficiency needs to be improved with a shorter response time. To realize these, dimethylaminoethyl methacrylate (DMAEMA) and methyltrimethoxysilane (MTMS) synthesized pH‐responsive copolymer (DMAEMA‐co‐MTMS) which grafted banana nanocellulose fiber made from wasted pseudostem to achieve the pH‐responsive aerogel (BCNA‐DcoM). BCNA‐DcoM exhibited hydrophilic/submerged lipophobicity under acidic conditions and hydrophobic/lipophilic under alkaline conditions. A response time of 3 s and a contact angle of 135° were shown when the mass ratio of banana nanocellulose suspension, MTMS, and DMAEMA‐co‐MTMS was 5:3:9. Moreover, BCNA‐DcoM possessed favorable mechanical friction properties, salt resistance (25% NaCl), compression resilience (50 cycles of compression at 60% strain), switchable wettability (>30 cycles), and highly efficient separation performance (>96%). The adsorption capacity of BCNA‐DcoM for oil is 80–184 times the initial weight of the aerogel based on the different oil densities. For practical applications, BCNA‐DcoM could continuously separate oil–water mixtures with the constant‐flow pump. The present work provides more possibilities for rapidly treating industrial oily wastewater with low‐cost and ecological banana pseudostem materials.

Experimental and Molecular Dynamics Simulation to Investigate Oil Adsorption and Detachment from Sandstone/Quartz Surface by Low-Salinity Surfactant Brines.

In this study, we explore the impact of monovalent (NaCl) and divalent (CaCl2) brines, coupled with sodium dodecyl sulfate (SDS) surfactant at varying low concentrations, on the detachment and displacement of oil from sandstone rock surfaces. Employing the sessile drop method and molecular dynamics simulations, we scrutinize the behavior of the brine solutions. Our findings reveal that both low salinity and low-salinity surfactant solutions induce a gradual shift in rock wettability toward a more water-wet state. This wettability transformation is not instantaneous but evolves over time, as observed through meticulous molecular motion analyses. Through contact angle measurements and molecular dynamics simulations, we delve into the molecular motion at subpore and micropore scales on sandstone/quartz surfaces. The adsorption of surface-active agents from the oil to the oil-brine interface results in a reduced interfacial tension, significantly contributing to oil displacement. Notably, low salinity concentrations ranging from 1000 to 10,000 ppm exhibit the lowest contact angles within 30 min across all solutions. However, higher concentrations deviate from this declining trend, especially with divalent ions like Ca2+, which bridge polar molecules onto the rock surface, resulting in an increased oil-wetting state. This research unveils the intricate molecular motions involved in employing low-salinity surfactant solutions for oil detachment from surfaces. Furthermore, it provides valuable insights into the underlying forces driving oil detachment and wettability alteration.

Numerical analysis of the heat transfer of gears under oil dip lubrication

Reliable gearbox operation is based on heat balance. The heat transfer of gears is closely related to the fluid flow of a gearbox. This study focuses on the heat transfer between oil dip-lubricated gears and fluid. A numerical analysis of the mechanisms and influences on the heat transfer coefficient of gears is carried out. The results show that the local interaction between gears and fluid strongly influences the gear heat transfer. The oil wetting and circumferential speed are particularly influential. The fling-off model is capable of predicting the heat transfer coefficient between gears and fluid with reasonable accuracy. The prediction accuracy of analytical models can be improved by incorporating fluid flow properties obtained from numerical calculations.

Nuclear magnetic resonance experiments on the time-varying law of oil viscosity and wettability in high-multiple waterflooding sandstone cores

A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2 spectrum, and the time-varying law of simulated oil viscosity in porous media is quantitatively characterized by nuclear magnetic resonance (NMR) experiments of high multiple waterflooding. A new NMR wettability index formula is derived based on NMR relaxation theory to quantitatively characterize the time-varying law of rock wettability during waterflooding combined with high-multiple waterflooding experiment in sandstone cores. The remaining oil viscosity in the core is positively correlated with the displacing water multiple. The remaining oil viscosity increases rapidly when the displacing water multiple is low, and increases slowly when the displacing water multiple is high. The variation of remaining oil viscosity is related to the reservoir heterogeneity. The stronger the reservoir homogeneity, the higher the content of heavy components in the remaining oil and the higher the viscosity. The reservoir wettability changes after water injection: the oil-wet reservoir changes into water-wet reservoir, while the water-wet reservoir becomes more hydrophilic; the degree of change enhances with the increase of displacing water multiple. There is a high correlation between the time-varying oil viscosity and the time-varying wettability, and the change of oil viscosity cannot be ignored. The NMR wettability index calculated by considering the change of oil viscosity is more consistent with the tested Amott (spontaneous imbibition) wettability index, which agrees more with the time-varying law of reservoir wettability.

Asphaltene Adsorption on Solid Surfaces Investigated Using Quartz Crystal Microbalance with Dissipation under Flow Conditions.

Asphaltenes can cause operational challenges in petroleum production facilities and adversely affect production by adsorption on mineral surfaces and alteration of the oil wettability of reservoirs. Therefore, understanding asphaltene adsorption mechanisms and their effects is crucial to improving the efficiency of oil production and reducing costs. In this study, we focus on understanding the impact of asphaltene concentration and the depositing environment of asphaltene adsorption on solid surfaces using the quartz crystal microbalance with dissipation (QCM-D) technique. The initial and long-term kinetics of adsorption at different concentrations were examined on three different solid surfaces including silicon dioxide to represent quartz mineral, stainless steel, and gold. The frequency-dissipation data showed evidence of monolayer adsorption initially, followed by multilayer formation. At short times, the adsorbed mass increased linearly with time, suggesting that the process was kinetically controlled rather than diffusion-controlled. The results were reproducible and did not depend on convection velocity but did depend on the surface material. At later stages, the monolayer development appeared to follow the random sequential adsorption (RSA) theory. Once multilayer adsorption commenced, the rates agreed well with the two-layer model of Zhu and Gu, 1990. The impact of asphaltene adsorption on the wettability of the surface was examined using contact angle studies, which showed decreasing water wettability with an increase in the adsorbed mass. The contact angle of water after 12 h of adsorption leveled off at around 100° on all three surfaces. Contact angle measurements were also used to evaluate if brine salinity causes the wettability alteration of surfaces with the adsorbed asphaltene. The results indicate that at 3% NaCl solution, the contact angle decreased only slightly by less than 2°.

Understanding the Corrosion Behaviour of Steel Under Alternate Oil/Water Wetting with Different Oil Viscosities

The corrosion behaviour of steel under alternate wetting conditions with various oil viscosities was investigated by an “alternate wetting cell,” combined with electrochemistry measurements, contact angle measurements, and molecular dynamics simulation. Under static conditions, corrosion was mitigated more efficiently with an increase of viscosity, because a large static friction force between high-viscosity oil and the steel surface prolongs the oil film lifetime and oil wetting time. Under dynamic conditions, the effect of oil viscosity on the corrosion and wetting behaviour of carbon steel was not dominated in comparison to that of the static conditions.

Effects of Sulfate Ions on Crude Oil Adsorption/Desorption on Carbonate Rocks: Experimental and Molecular Simulations.

In the background of the strong oil wettability and low production by water flooding in carbonate reservoirs, low-salinity water containing sulfate ions can significantly change the surface wettability of carbonate rocks and thus increase the sweeping area; however, the absorption and desorption mechanisms of the oil film in the carbonate rock surface remain unclear. This paper analyzed the wettability alternation of carbonate rocks' surface in pure water and sodium sulfate solution. At the same time, MD (Materials Studio) software was used to simulate the formation process of the oil film and the effect of sulfate ions on the desorption of the oil film on the surface of carbonate rocks. The experimental results showed that sodium sulfate solution could accelerate the rate from oil-wet to water-wet and the final contact angle (49°) was smaller than that in pure water. The simulation results showed that dodecane molecules moved to the surface of calcite to form a double layer of the oil film and that the oil film near the calcite surface had a high-density stable structure under the van der Waals and electrostatic action. The hydrating sulfate ions above the oil film broke through the double oil film to form a water channel mainly under the action of electrostatic force and a hydrogen bond and then adsorbed on the calcite surface. A large number of water molecules moved down the water channel based on a strong hydrogen bonding force and crowded out the oil molecules on the surface of the calcite, resulting in the oil film detachment. This work aims to explain the interaction of oil molecules, water molecules, and SO42- ions at the molecular scale and guide the practical application of low-salinity water flooding in carbonate reservoirs.

Impact of engineered water in modulating the wettability of oil–brine–rock system for improved oil recovery

AbstractLow salinity water injection stands as a progressive method for enhanced oil recovery, representing a current focus of extensive research. Understanding wettability alteration in crude oil is hindered by its intricate nature, posing a challenge for researchers. In order to better understand wettability alteration and underlying phenomena in an oil–brine–rock system, a fundamental study was carried out using pure hydrocarbon (aliphatic: n‐heptane; aromatic: toluene) and crude oil on quartz surface against engineered water consist of monovalent (NaCl) and divalent (MgSO4) salts in various compositions (NaCl:MgSO4: 100:0; NaCl:MgSO4: 0:100; NaCl:MgSO4: 75:25; NaCl:MgSO4: 50:50; NaCl:MgSO4: 25:75). The variables under investigation include temperature (25 to 65°C), pure hydrocarbons (toluene, n‐heptane), crude oil (Indian offshore), and brine (B1 to B5) with concentration (0 to 20,000 ppm). The findings show that when brine solution contains solely NaCl salt at a concentration of 2000 ppm, n‐heptane exhibits a minimum contact angle on quartz plate. Contrarily, toluene exhibits a low contact angle with a brine solution that only contains MgSO4 salt at a concentration of 2000 ppm. The intriguing finding is that when monovalent and divalent salts are equal (NaCl:MgSO4: 50:50) in the brine, crude oil exhibits the smallest contact angle on quartz. Additionally, temperature and contact angle are directly related for all oil types. The optimal brine for achieving the minimum contact angle on quartz surface is (B1)2000 for n‐heptane, (B2)2000 for toluene, and (B4)2000 for crude oil for the current study. The study findings indicate that the alteration in wettability due to brine composition and salinity varies among different oil samples, characterized by purely aliphatic, aromatic, and mixed components, and it depends on the type of salt compositions. Higher salts concentration minimally affects n‐heptane but influences toluene and crude oil contact angles.

The role of air relative humidity on the wettability of Pseudomonas fluorescens AR11 biofilms

Biofilms are complex porous materials formed by microorganisms, polysaccharides, proteins, eDNA, inorganic matter, and water. They are ubiquitous in various environmental niches and are known to grow at solid-liquid, solid-air and air-liquid interfaces, often causing problems in several industrial and sanitary fields. Their removal is a challenge in many applications and numerous studies have been conducted to identify promising chemical species as cleaning agents. While these substances target specific components of biofilm structure, the role of water content in biofilm, and how it can influence wettability and detergent absorption have been quite neglected in the literature. Estimating water content in biofilm is a challenging task due to its heterogeneity in morphology and chemical composition. In this study, we controlled water content in Pseudomonas fluorescens AR 11 biofilms grown on submerged glass slides by regulating environmental relative humidity after drying. Interfacial properties of biofilm were investigated by measuring wetting of water and soybean oil. The morphology of biofilm structure was evaluated using Confocal Laser Scanning Microscopy and Scanning Electron Microscopy. The results showed that biofilm water content has a significant and measurable effect on its wettability, leading to the hypothesis that a preliminary control of water content can play a crucial role in biofilm removal process.

Cellulose acetate-based composite fibrous membrane with asymmetric wettability for directional water transport and high-flux oil–water separation

Cellulose acetate-based composite fibrous membrane with asymmetric wettability for directional water transport and high-flux oil–water separation

A New Mechanistic Model for Wettability-Altering Surfactant Floods in Carbonates

Summary Surfactants and low-salinity brines have been shown to be effective for enhanced oil recovery in carbonate rocks through wettability alteration (WA). Oil wettability of carbonates is ascribed to the adsorbed organic acid components in oil. The removal of the adsorbed acids leads to WA. Previous experiments with wettability-altering surfactants have shown the following: WA is a slow process; acid removal is irreversible in most cases; surfactants can access the rock surface in water-wet regions and at three-phase contact lines rather than the entire rock surface; surfactant molecules become inactive after interactions with acids. Existing models/simulators do not incorporate the aforementioned observations. In this work, a multiphase, multicomponent, finite-difference reservoir simulator incorporating a new mechanistic model for WA was developed. The model captures the key physicochemical reactions between adsorbed acids and surfactant molecules and honors the four experimental evidences. The model was first tested at the core scale. The simulation results demonstrated that the model can accurately predict waterflood performance in rocks with various wettability. It can also effectively account for the influence of injection rates in surfactant flood experiments. The effectiveness of the surfactant, controlled by an interaction constant in the model, was found to be a dominant factor. The model was also tested for field-scale pilot tests. The results revealed that total quantity of chemicals injected and the injection rate have a more pronounced effect on oil recovery compared to the timing of surfactant treatment and the concentration of surfactant slug.

EXPLORING THE WETTABILITY CHARACTERISTICS OF ARGILLACEOUS SILTSTONE WITH IMBIBITION AND NMR TECHNIQUE FOR MARINE RESERVOIR EXPLOITATION

The argillaceous siltstone reservoirs in South China Sea involves a wide variety of fossil resources, such as gas hydrate, marine oil, natural gas, and other mineral resources. The argillaceous siltstone with mixed wettability characteristics is easily dispersed in water, and it is difficult to study the wettability of argillaceous siltstone based on water imbibition technique. In this work, an innovative method is proposed to demonstrate the mixed wettability based on imbibition and nuclear magnetic resonance (NMR) technique. The contact angle results show that the affinity of argillaceous siltstone for oil is stronger than that for water. However, the imbibition volume of water is much larger than that of oil. The oil imbibition curve is linear, while water imbibition curve has a two-stage feature. This difference can be explained by the expansion of clay, where more water wet surfaces are exposed to the liquid, leading to changes in wettability. In addition, the coexistence of organic matter and inorganic clay minerals results in a mixed wetting characteristic. Based on NMR technology, a micro wettability index is proposed to quantitatively characterize the micro wettability heterogeneity. The micro water (or oil) wettability index of micropores (0.01-10 ms) is approximately equal to 0.5, indicating the mixed wettability. The micro water wettability index of mesopores (10-500 ms) is approximately equal to 1.0, indicating strong water wettability. These pores or cracks may be induced by clay minerals expansion. The micro oil wettability index of macropores (> 500 ms) is approximately equal to 1.0, indicating strong oil wettability, which is resulted from significant accumulation of organic debris enrichment. It is of great significance to improve the exploration and exploitation efficiency of mineral resources in the South China Sea.

The mobilization mechanism of low oil saturation reservoirs

After fracturing with a guar fluid system in Chang 8 oil reservoir, some wells have high oil production, and some have low production and even only produce water. Therefore, a comparative study is carried out in oil-producing and water-producing wells. The results show that: ① Organic wax adsorbed in oil-producing and water-producing well core pores accounts for 95.39% and 56.67%, respectively, making wells strong oil-wet. A certain proportion of inorganic salts and some other oil-wet organic compounds exist in water-producing wells. ② Under the reservoir conditions, the oil wettability of the water-producing well core is strong, and its original formation wettability is also oil-wet. The original wettability of the oil-producing well formation is water-wet, with oil production capacity. ③ The core residual oil saturation using the guar fluid is 24.7%–29.87%. This results in no oil phase permeability or difficulty to mobilize oil in most oil reservoirs. ④ Forced displacement can mobilize oil in large pores and has a significant effect in producing well, with mobilization efficiency of 53.49%. This article elucidates the wettability formation and crude oil mobilization mechanism of two types of wells, providing direction for the development of this type of reservoir.