Enhancing Oil Recovery in Low Permeability Reservoirs through CO Miscible Flooding: Mechanisms and Dynamics.

Understanding the dynamic characterization of the CO miscible flooding process in low permeability reservoirs and its mechanism for oil recovery enhancement is crucial for controlling CO miscible flooding sweep efficiency and further enhancing oil recovery. This study was conducted in a low permeability reservoir in Jilin, China, using both online nuclear magnetic resonance CO miscible flooding and long-core CO miscible flooding experiments. A refined dynamic characterization of the CO miscible flooding process from the macroscopic core scale to the microscopic pore scale was achieved through multiple spatial online nuclear magnetic resonance testing methods.

Numerical study on the stimulation effect of boundary sealing and hot water injection in marine challenging gas hydrate extraction.

This study proposed a novel development mode combining boundary sealing and hot water injection to address the challenges of gas leakage, limited reservoir sensible heat, boundary water intrusion, and low productivity faced by challenging hydrate extraction, and the stimulation effect was numerically investigated with Shenhu hydrates as the geological background. The results showed that lower boundary permeability facilitated pressure propagation and achieved volumetric dissociation of hydrates, whereas insufficient formation energy resulted in substantial gas retention. Hot water injection was effective for stimulation, but open boundaries could not maintain the high injection pressure, leading to massive hot water losses and gas escapes.

Mud Cake Improver Mul-GX with Lubrication and Interface Enhancement Effect and Its Action Mechanism.

In view of the problems in which the solid content of drilling fluid increases in the middle and late stages of horizontal well drilling, the lubricity of mud cakes on the borehole wall decreases, and the friction of pipe string increases due to the gradual thickening of mud cakes, which leads to the sticking and the obvious decrease of cementing strength at the second interface, a mud cake improver Mul-GX with lubrication and interface enhancement effect was studied in this paper. Based on the hydration and filling mechanism, the lubricity of the mud cake was improved, its thickness was reduced, and its strength was improved through synergistic effects of solvated water film lubrication and buffering, hardening and crystallization of gelled substances, and filling and dispersion of elastic particles. The mud cake improver Mul-GX is composed of the metasilicate GX-ZQ, polymer copolymer GX-JB, and polymer GX-TX, and the mass ratio of each component was GX-ZQ: GX-JB: GX-TX = 15:1:0.

Synergistic Effect of Betaines and Dialkyl Chain Anionic Surfactants on Interfacial Arrangement: A Molecular Dynamics Simulation Study.

Mixed systems of betaines and anionic surfactants can have a significant synergistic effect and greatly reduce the interfacial tension (IFT), which has attracted an extensive amount of attention. However, this synergistic effect requires an anionic surfactant and betaine molecular size matching, which limits the scope of its application. In this work, we studied three mixed systems of sodium dialkyl sulfosuccinate (AOT) and betaines with different sizes by molecular dynamics simulation and an IFT experiment and explored the interfacial behavior and synergistic mechanism of AOT in single and mixed systems.

Preparation and performance evaluation of a novel temperature-resistant anionic/nonionic surfactant.

Aiming at oil extraction from a tight reservoir, the Jilin oil field was selected as the research object of this study. Based on the molecular structures of conventional long-chain alkyl anionic surfactants, a new temperature-resistant anionic/nonionic surfactant (CPEC) was prepared by introducing polyoxyethylene and polyoxypropylene units into double-chain alcohols. The resulting structures were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (H-NMR), and electrospray ionization mass spectrometry (ESI-MS).

Research on Performance Evaluation of Polymeric Surfactant Cleaning Gel-Breaking Fluid (GBF) and Its Enhanced Oil Recovery (EOR) Effect.

Clean fracturing fluid has the characteristics of being environmentally friendly and causing little damage to reservoirs. Meanwhile, its backflow gel-breaking fluids (GBFs) can be reutilized as an oil displacement agent. This paper systematically evaluates the feasibility and EOR mechanism of a GBF based on a polymer surfactant as an oil displacement system for reutilization.

Toward Estimating CO Solubility in Pure Water and Brine Using Cascade Forward Neural Network and Generalized Regression Neural Network: Application to CO Dissolution Trapping in Saline Aquifers.

Predicting carbon dioxide (CO) solubility in water and brine is crucial for understanding carbon capture and storage (CCS) processes. Accurate solubility predictions inform the feasibility and effectiveness of CO dissolution trapping, a key mechanism in carbon sequestration in saline aquifers. In this work, a comprehensive data set comprising 1278 experimental solubility data points for CO-brine systems was assembled, encompassing diverse operating conditions.

Characterization and treatment of oily sludge: A systematic review.

Oily sludge is a prevalent hazardous waste generated in the petroleum industry, and effectively treating it remains a key challenge for the petroleum and petrochemical sectors. This paper provides an introduction to the origin, properties, and hazards of oil sludge while summarizing various treatment methods focused on reduction, recycling, and harmlessness. These methods include combustion, stabilization/solidification, oxidation and biodegradation techniques, solvent extraction, centrifugation, surfactant-enhanced oil recovery processes as well as freezing-thawing procedures.

Enhanced Polyacrylamide Degradation via OH Radical-Initiated Single-Electron Transfer.

Hydroxyl (OH) radicals, as common radicals in aqueous environments, play an important role in inducing the degradation reactions of polymers. However, understanding the fundamental mechanisms of radical-induced degradation of polymers at the atomic level remains a formidable challenge. In this study, we employ density functional theory to investigate the geometric and electronic structural properties of polyacrylamide (PAM) in (-CHCHCONH-) ( = 2-6) complexes.

Single-Factor Comprehensive Reservoir Quality Classification Evaluation-Taking the Hala'alat Mountains at the Northwestern Margin of the Junggar Basin as an Example.

In the process of petroleum geology exploration and development, reservoir quality evaluation is an essential component. However, conventional reservoir quality evaluation methods are no longer able to provide accurate and comprehensive assessments for all types of reservoirs. Therefore, the comprehensive evaluation of reservoir quality using multiple single factors is of significant importance in improving the level of reservoir quality assessment and enhancing the effectiveness of oil and gas exploration techniques.

Cross-Scale Seepage Characteristics of Fractured Horizontal Wells in Tight Gas Reservoirs.

Tight gas reservoirs are rich in microscale pores and fractures. The effect of microscale gas seepage in tight sandstone matrix on gas well productivity cannot be ignored. At present, the effect of microscale gas flow on the well testing model of fractured horizontal wells has not been systematically studied.

CO improves the anaerobic biodegradation intensity and selectivity of heterocyclic hydrocarbons in heavy oil.

Heterocyclic hydrocarbons pollution generated by oil spills and oilfield wastewater discharges threatens the ecological environment and human health. Here we described a strategy that combines the greenhouse gas CO reduction with microbial remediation. In the presence of nitrate, CO can improve the biodegradation efficiency of the resins and asphaltenes in heavy oil, particularly the biodegradation selectivity of the polar heterocyclic compounds by the newly isolated Klebsiella michiganensis.

Performance Evaluation and Action Mechanism Analysis of a Controllable Release Nanocapsule Profile Control and Displacement Agent.

With the acceleration in oilfield developments, reservoir advantage channels have been gradually developed. This has led to ineffective circulation in the oilfield injection system and a significant decrease in production. The profile control and displacement technology of low-permeability and heterogeneous reservoirs are in urgent need of updating.

Solubility Variation and Prediction Model of CO in Water-Bearing Crude Oil.

The solubility of CO in water-bearing crude oil is of great significance for the calculation of crude oil reserves, the development of CO-EOR (CO-enhanced oil recovery), CO-CCUS (carbon capture, utilization, and storage), and CO assisted steam huff-and-puff technology, and the optimization of the design of CO for heavy oil pipeline transportation. In order to determine the variation of the solubility of water-bearing crude oil by injecting CO into the formation, taking the Upper Wuerhe Formation reservoir in the 5 East Block as an example, the study of the dissolution characteristics of CO in water-bearing crude oil at different temperature and pressure conditions was carried out by using a high-temperature and high-pressure reaction kettle. At the same time, a new solubility prediction model of CO in water-bearing crude oil was proposed based on the existing solubility prediction models.

Improvement of Emulsion Stability and Plugging Performance of Nanopores Using Modified Polystyrene Nanoparticles in Invert Emulsion Drilling Fluids.

Drilling fluid invasion and pressure transmission caused by the development of micropores and fractures in shale oil and gas formations are the major factors contributing to wellbore instability during drilling using oil-based drilling fluids (OBFs). In this study, a modified polystyrene latex (MPL) material was synthesized through emulsion polymerization and was characterized using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), particle size analysis, scanning electron microscopy (SEM) observations, and contact angle testing. The influence of the MPL on the stability of a water-in-oil emulsion was analyzed sedimentation observations and electrical stability tests.

Reservoir quality and its controlling diagenetic factors in the Bentiu Formation, Northeastern Muglad Basin, Sudan.

The Abu Gabra and Bentiu formations are widely distributed within the interior Muglad Basin. Recently, much attention has been paid to study, evaluate and characterize the Abu Gabra Formation as a proven reservoir in Muglad Basin. However, few studies have been documented on the Bentiu Formation which is the main oil/gas reservoir within the basin.

Stimulation and Sequestration Mechanism of CO Waterless Fracturing for Continental Tight Oil Reservoirs.

CO fracturing is a promising technology for oil field development in tight, continental deposits, with potential advantages of enhanced oil recovery (EOR), CO sequestration, and water conservation. Compared with CO-EOR techniques, such as CO huff and puff and CO flooding, CO can interact with reservoir rock and fluid under higher pressure conditions during fracturing, resulting in CO stimulation and sequestration effects that differ from those that occur during conventional CO-EOR. In this paper, the CO interactions between CO and reservoirs in continental tight oil reservoirs under fracturing conditions are systematically studied through laboratory experiments.

Evaluation of the Shale Oil Reservoir and the Oil Enrichment Model for the First Member of the Lucaogou Formation, Western Jimusaer Depression, Junggar Basin, NW China.

The Lucaogou Formation (Fm) in the Jimusaer depression is the first large-scale development of a terrigenous clastic sedimentary shale oil reservoir in China. Nearly one billion tons of shale oil resources have been discovered. However, the current exploration and development is concentrated in the eastern part of the sag.

Indigenous bacterial community and function in phenanthrene-polluted coastal wetlands: Potential for phenanthrene degradation and relation with soil properties.

The Yellow River Delta, adjacent to Shengli Oilfield, has a potential risk of petroleum pollution. In this study, soil samples were collected from phenanthrene (PHE)-polluted (adjacent to abandoned oil well, Zone D) and non-polluted (far away from abandoned oil well, Zone E) coastal wetlands. The influence of PHE pollution on indigenous bacterial community and function, and their relationship with soil characteristics were investigated.

Drag Reduction Performance and Mechanism of Hydrophobic Polymers in Fresh Water and Brine.

Three kinds of drag reducer were synthesized by inverse emulsion polymerization and named PHWAM-1, PHWAM-2, and PHWAM-3. Drag reduction (DR) tests showed that the three drag reducers have different DR characteristics in fresh water and various saline waters because of their different types of hydrophobic monomers. PHWAM-1, without hydrophobic monomers, performs better in fresh water, while PHWAM-2 and PHWAM-3, with hydrophobic monomers, perform better in brine.

Study on Morphology and Rheological Property of Organoclay Dispersions in Soybean Oil Fatty Acid Ethyl Ester over a Wide Temperature Range.

This work attempted to establish the relationship between the dispersion morphology and the viscous flow behavior of clay dispersions in soybean oil fatty acid ethyl ester (FAEE) at 2 and 65 °C. The clays used in this study include raw montmorillonite (Mt) and three kinds of organoclays prepared by ion exchange modification of Mt by cetyltrimethylammonium chloride (OC16), dihexadecyldimethylammonium chloride (ODC16), and trihexadecylmethylammonium chloride (OTC16), respectively. The X-ray diffraction and water contact angle results demonstrated that greater alkyl chain number of surfactants led to greater interlayer space and stronger hydrophobicity of organoclays.

Pseudomonas jilinensis sp. nov., Isolated from Oil Production Water of Jilin Oilfield in China.

A Gram-stain-negative, rod-shaped bacterial strain JS15-10A1 was isolated from oil production water. Its optimum growth was observed at 37 °C, pH 7.0, and 3% (w/v) NaCl.