Injection Profile Research Articles

Prospects and current state of chemical EOR methods applied in Kazakhstan

At present, at almost all fields of the Republic of Kazakhstan the main technology of oil recovery enhancement is the traditional method of waterflooding of productive formations. Many oil and gas fields in Kazakhstan are at a late stage of development and are categorized as «mature» fields. In the global experience of mature field development, the key focus is on the application of enhanced oil recovery (EOR) techniques - chemical, thermal, gas and microbiological methods. This paper considers the application of chemical EOR at a number of Kazakh fields such as Zaburunye, North Buzachi, Kalamkas, East Moldabek. As the results of the pilot studies have shown, the most effective EOR here is the application of polymer flooding. It should also be noted that polymer flooding is successfully applied in Kazakhstan for high-viscosity oil fields such as North Buzachi (oil viscosity 316-417 mPa·s), East Moldabek (oil viscosity 246-377 mPa·s). In this case, water cut, smoothing of injectivity profile and, as a result, increase of oil production is achieved. Successful application of the technology largely depends on the parameters of physical and chemical impact at each stage - the volume of injection of gel-polymer composition, concentration of ingredients, the flow rate of filtered water, the presence and linear size of cracks, the permeability of pore channels and etc. Polymer flooding applied in Kazakhstan showed its technological and economic efficiency on the example of pilot tests, laboratory studies, which reduces water cut and increases oil production. Widespread use of EOR methods would allow increasing recoverable oil reserves by at least 5-10 %. Keywords: Enhanced Oil Recovery (EOR); gas Injection; hydrocarbon recovery methods; chemical EOR methods; thermal EOR methods; oil production; polymer flooding; oil recovery.

Research on the processing and interpretation methods of distributed fiber optic vibration signal logging injection profiles

The oil and gas industry currently faces the dual challenges of improving extraction efficiency and reducing environmental impacts. Traditional well monitoring technologies are increasingly unable to meet the demands of modern oil and gas extraction due to technological limitations and environmental concerns. Distributed Acoustic Sensing (DAS) technology, which utilizes optical fibers as sensing elements, enables real-time and accurate monitoring of the CO2 injection process in wells. However, DAS technology encounters issues such as weak amplitude signals and noise interference in practical applications. In response, a comprehensive method for processing and interpreting DAS logging data for CO2 injection wells has been proposed. This method involves restoring amplitude signals through wavefront energy compensation and applying Gaussian filtering and wavelet threshold denoising algorithms for noise reduction. The processed results are classified using the K-Medoids clustering algorithm and the CO2 absorption volume in the injection layer is calculated using the integral area method. The accuracy and practicality of this method have been validated through comparative analysis with pulse neutron oxygen activation logging results. This approach aims to address the challenges faced by DAS technology in the oil and gas industry, thereby providing technical support for the efficient, environmentally friendly, and intelligent management of oil and gas fields.

Variation in Path Lengths of Turbulent Magnetic Field Lines and Solar Energetic Particles

Modeling of time profiles of solar energetic particle (SEP) observations often considers transport along a large-scale magnetic field with a fixed path length from the source to the observer. Here, we point out that variability in the turbulent field line path length can affect the fits to SEP data and the inferred mean free path and injection profile. To explore such variability, we perform Monte Carlo simulations in representations of homogeneous 2D MHD + slab turbulence adapted to spherical geometry and trace trajectories of field lines and full particle orbits, considering proton injection from a narrow or wide angular region near the Sun, corresponding to an impulsive or gradual solar event, respectively. We analyze our simulation results in terms of field line and particle path length statistics for 1° × 1° pixels in heliolatitude and heliolongitude at 0.35 and 1 au from the Sun, for different values of the turbulence amplitude b/B 0 and turbulence geometry as expressed by the slab fraction f s . Maps of the most probable path lengths of field lines and particles at each pixel exhibit systematic patterns that reflect the fluctuation amplitudes experienced by the field lines, which in turn relate to the local topology of 2D turbulence. We describe the effects of such path length variations on SEP time profiles, both in terms of path length variability at specific locations and the motion of the observer with respect to turbulence topology during the course of the observations.

The 2019 Raikoke eruption as a testbed used by the Volcano Response group for rapid assessment of volcanic atmospheric impacts

Abstract. ​​​​​​​The 21 June 2019 Raikoke eruption (48° N, 153° E) generated one of the largest amounts of sulfur emission to the stratosphere since the 1991 Mt. Pinatubo eruption. Satellite measurements indicate a consensus best estimate of 1.5 Tg for the sulfur dioxide (SO2) injected at an altitude of around 14–15 km. The peak Northern Hemisphere (NH) mean 525 nm stratospheric aerosol optical depth (SAOD) increased to 0.025, a factor of 3 higher than background levels. The Volcano Response (VolRes) initiative provided a platform for the community to share information about this eruption which significantly enhanced coordination efforts in the days after the eruption. A multi-platform satellite observation subgroup formed to prepare an initial report to present eruption parameters including SO2 emissions and their vertical distribution for the modeling community. It allowed us to make the first estimate of what would be the peak in SAOD 1 week after the eruption using a simple volcanic aerosol model. In this retrospective analysis, we show that revised volcanic SO2 injection profiles yield a higher peak injection of the SO2 mass. This highlights difficulties in accurately representing the vertical distribution for moderate SO2 explosive eruptions in the lowermost stratosphere due to limited vertical sensitivity of the current satellite sensors (±2 km accuracy) and low horizontal resolution of lidar observations. We also show that the SO2 lifetime initially assumed in the simple aerosol model was overestimated by 66 %, pointing to challenges for simple models to capture how the life cycle of volcanic gases and aerosols depends on the SO2 injection magnitude, latitude, and height. Using a revised injection profile, modeling results indicate a peak NH monthly mean SAOD at 525 nm of 0.024, in excellent agreement with observations, associated with a global monthly mean radiative forcing of −0.17 W m−2 resulting in an annual global mean surface temperature anomaly of −0.028 K. Given the relatively small magnitude of the forcing, it is unlikely that the surface response can be dissociated from surface temperature variability.

SUBSTANTIATION OF METHOD FOR LEVELING INJECTIVITY PROFILE UNDER CONDITIONS OF CARBONATE RESERVOIRS OF FIELD NAMED AFTER R. TREBSA

At the moment, the issue of reducing water cut during the development of carbonate fractured reservoirs is relevant. In the work, the object of the study is the carbonate deep reservoirs of the R. Trebs field. According to the field development analysis, there are production wells with sharp unpredictable breakthrough of injected water.In order to increase the coverage of pay zones by waterflooding, it is necessary to use methods aimed at limiting the filtration of injected water into water-flooded intervals.High formation temperature and mineralization of formation water are complicating factors in the selection of the injection profile alignment (runway) technology.Taking into account the criteria specified in the work, potential candidates for testing the technology were selected for the runway.The article analyzed the advantages and disadvantages of the existing runway methods used when exposed to injection wells. The criteria for the applicability of various technologies based on the use of: polymer/gel compositions, emulsion compositions, including reverse emulsions, injection of aqueous salt solutions, silicate, thermotropic and complex reagents are highlighted. Technologies and compositions based on water-soluble polymers that form viscoelastic compositions when crosslinkers of various nature are added are recognized as the most promising for the conditions of the fractured reservoir of the Trebs field.Particular attention is paid to laboratory experiments aimed at studying the physical and chemical properties of crosslinked polymer systems, conducting filtration experiments, determining the applicability of the technology for the geological and physical conditions of the study object.According to the results of physicochemical experiments, such parameters as the time of dissolution of reagents, compatibility with formation water, time and temperature of gelling were determined. Based on the shear test, rheological parameters of the investigated polymer systems are determined. Testing was carried out to determine the conditions under which the crosslinked polymer composition breaks down.Filtration experiments were carried out on linear and volumetric models of the formation using core material from the Trebs field to determine the reagent with the highest colmating abilities calculated from the residual resistance factor.

An integration of the numerical and soft computing approaches for determining inflow control device flow area in water injection wells

To avoid or mitigate the unwanted water and gas content, inflow control devices (ICDs) are designed and installed in the well to disturb the water and gas breakthrough which are trying to overtake the oil inflow, water and gas coning and sand production. Smart wells with permanent downhole valves such as ICDs are used to balance production and injection in wells. A paramount issue regarding using downhole control devices is determining the required cross-sectional area of them for control of the imposed pressure drop across the device to stabilize the fluid flow. Current methods for calculating the opening size of the ICDs are mainly based on sensitivity analysis of the ICD flow area or optimization algorithms coupled with simulation models. Although these approaches are quite effective in oil field cases, they tend to be time-consuming and require demanding system models. This paper presents a fast analytical method to determine the ICD flow area validated by a genetic algorithm (GA). Analytically, a closed-form expression is introduced by manipulating Darcy’s law applicable to multi-layer injection wells with different layer properties to balance the injection profile in the reservoir pay zone, based on equalizing injected front velocity in layers with different permeability. Considering various scenarios of analytical technique, GA optimization, and sensitivity analysis scenarios for ICD cross-sectional area determination, results for oil recovery, water production, water breakthrough time, and net present value (NPV) are discussed and compared. NPV values obtained by both analytical and GA approaches are virtually identical and greater than those of other scenarios. Compared to the base field case, the analytical method improved the oil recovery by almost 1%, reduced water production by almost 91%, and synchronized the water breakthrough time of high- and low-permeability layers (from a ratio of 1.76–1.06). The proposed analytical solution proved to be capable of providing desirable results with only one reservoir simulation run in contrast to GA and sensitivity analysis scenarios which require iterative simulation runs. The proposed analytical solution outperformed the GA as it is less computationally demanding in addition to its success in case of lowering water production for the field data. The findings of this study can help for a better understanding of the situation where water injection into the oil reservoir is problematic as the layers present different permeabilities which can induce problems such as early water breakthrough from the more permeable layer and hinder the success of the water injection process. Using ICDs and a faster and more accurate approach to calculate its cross-sectional area such as the analytical method that was used in this study can greatly increase the success rate of water injection in case of oil recovery and lower the amount of the produced water.

Improving the Accuracy of Predictive 2D-LC Optimization Strategies: Incorporation of Simulated Elution Profiles to Account for Injection Band Broadening in Online Comprehensive Two-Dimensional Liquid Chromatography.

Method development in online comprehensive two-dimensional liquid chromatography (LC × LC) requires the selection of a large number of experimental parameters. The complexity of this process has led to several computer-based LC × LC optimization algorithms being developed to facilitate LC × LC method development. One particularly relevant challenge for predictive optimization software is to accurately model the effect of second dimension (2D) injection band broadening under sample solvent mismatch and/or sample volume overload conditions. We report a novel methodology that combines a chromatographic numerical simulation model capable of predicting elution profiles of analytes under conditions where peak distortion occurs with a predictive multiparameter Pareto optimization approach for online LC × LC. Preliminary method optimization is performed using a theoretical model to predict 2D injection profiles, and optimal experimental configurations obtained from the Pareto fronts are then subjected to further optimization using the simulation model. This approach drastically reduces the number of simulations and therefore the computational demand. We show that the optimal experimental conditions obtained in this manner are similar to those obtained using a complete optimization using only the simulation model. Online HILIC × RP-LC separation of phenolic compounds was used to compare experimental data to simulated two- and three-dimensional contour plots. The main advantage of the proposed approach is the ability to predict the formation of split or deformed peaks in the 2D, a significant benefit in online LC × LC method optimization, especially for separation combinations with mismatched mobile phases. A further benefit is that simulated elution profiles can be used for the visualization of predicted two-dimensional chromatograms for method selection.

Evaluation of acceptance and preference of topical lidocaine application versus articaine injection anesthesia after nonsurgical periodontal treatment: A randomized clinical trial.

To compare acceptance and preference of topical lidocaine gel anesthesia with articaine injection anesthesia in patients with moderate periodontitis undergoing scaling and root debridement. Ninety-one patients completed this randomized multicenter split-mouth controlled study and underwent two separate periodontal treatment sessions on different days, one with a topical intrapocket lidocaine gel application and the other with an articaine injection anesthesia in a different order depending on randomization. Parameters measured were the patients' preference for topical lidocaine gel anesthesia or injection anesthesia with articaine (primary efficacy criterion), their maximum and average pain, and their intensity of numbness as well as experience of side effects; the probing depth; and the dentists' preference and their evaluations of handling/application, onset and duration of anesthetic effect, and patient compliance. After having experienced both alternatives, 58.3% of the patients preferred the topical lidocaine gel instillation into the periodontal pockets. The safety profile of the lidocaine gel differed positively from the safety profile of articaine injection in type and frequency of adverse drug reactions. The dentists' acceptance and preference regarding either anesthetic method studied were balanced. Instillation of lidocaine gel into the periodontal pocket is a preferred alternative to injection anesthesia for most of the patients and an equivalent alternative for dentists in nonsurgical periodontal therapy.

Improved estimates of smoke exposure during Australia fire seasons: importance of quantifying plume injection heights

Abstract. Wildfires can have a significant impact on air quality in Australia during severe burning seasons, but incomplete knowledge of the injection heights of smoke plumes poses a challenge for quantifying smoke exposure. In this study, we use two approaches to quantify the fractions of fire emissions injected above the planetary boundary layer (PBL), and we further investigate the impact of plume injection fractions on daily mean surface concentrations of fine particulate matter (PM2.5) from wildfire smoke in key cities over northern and southeastern Australia from 2009 to 2020. For the first method, we rely on climatological, monthly mean vertical profiles of smoke emissions from the Integrated Monitoring and Modelling System for wildland fires (IS4FIRES) together with assimilated PBL heights from NASA Modern-Era Retrospective Analysis for Research and Application (MERRA) version 2. For the second method, we develop a novel approach based on the Multi-angle Imaging SpectroRadiometer (MISR) observations and a random forest, machine learning model that allows us to directly predict the daily plume injection fractions above the PBL in each grid cell. We apply the resulting plume injection fractions quantified by the two methods to smoke PM2.5 concentrations simulated by the Stochastic Time-Inverted Lagrangian Transport (STILT) model in target cities. We find that characterization of the plume injection heights greatly affects estimates of surface daily smoke PM2.5, especially during severe wildfire seasons, when intense heat from fires can loft smoke high in the troposphere. However, using climatological injection profiles cannot capture well the spatiotemporal variability in plume injection fractions, resulting in a 63 % underestimation of daily fire emission fluxes injected above the PBL in comparison with those fluxes derived from MISR injection fractions. Our random forest model successfully reproduces the daily injected fire emission fluxes against MISR observations (R2=0.88, normalized mean bias = 10 %) and predicts that 27 % and 45 % of total fire emissions rise above the PBL in northern and southeastern Australia, respectively, from 2009 to 2020. Using the plume behavior predicted by the random forest method also leads to better model agreement with observed surface PM2.5 in several key cities near the wildfire source regions, with smoke PM2.5 accounting for 5 %–52 % of total PM2.5 during fire seasons from 2009 to 2020.

An improved radioactive tracer response analysis and injection profile quantification method based on intelligent algorithms

An improved radioactive tracer response analysis and injection profile quantification method based on intelligent algorithms

Optimization procedure for conformance control

The article is devoted to the development of an optimization procedure for conformance control treatment. Currently, due to the significant share of reservoirs with high water cut, it is relevant to use methods that allow reducing the rate of production water cut increase. One of the most common methods to do this is to improve conformance by injecting suspension into the reservoir. The classical model of deep bed suspension migration has shown itself well for calculating the technological parameters of treatment, but it does not contain criteria for optimizing the process. The introduction of such criteria and their physical justification is the purpose of this work. The following objectives were set: modification of the classical model of deep bed suspension migration for layered strata, introduction of criteria of suspension treatment efficiency, and optimization of the process. Mathematical model consists of mass conservation laws and Darcy’s law. Initial data were selected for one of the fields in West Siberia, where suspension treatments were carried out to improve conformance. The field experience of these treatments is analyzed, the wells where the treatment was successful are determined. The new criterion for the effectiveness of suspension treatment is introduced. This criterion is the difference in the standard deviations of the flow rate along the layers before and after the treatment. It is established that this difference more clearly demonstrates the injectivity profile exchange than the classical Dykstra-Parsons criterion. The optimization procedure allows assessing the required slug volume that provides the maximum injectivity profile redistribution.

Advanced Numerical Analysis of In-Cylinder Combustion and NOx Formation Using Different Chamber Geometries

In diesel engines, emission formation inside the combustion chamber is a complex phenomenon. The combustion events inside the chamber occur in microseconds, affecting the overall engine performance and emissions characteristics. This study opted for using computational fluid dynamics (CFD) to investigate the combustion patterns and how these events affect nitrogen oxide (NOx) emissions. In this study, a diesel engine model with a flat combustion chamber (FCC) was developed for the simulation. The simulation result of the heat release rate (HRR) and cylinder pressure was validated with the experimental test data (the engine test was conducted at 1500 rpm at full load conditions). The validated model and its respective boundary conditions were used to investigate the effect of modified combustion chamber profiles on NOx emissions. Modified chambers, such as a bathtub combustion chamber (BTCC) and a shallow depth chamber (SCC), were developed, and their combustion events were analysed with respect to the FCC. This study revealed that combustion events such as fuel distribution, unburnt mass fractions, temperature and turbulent zones directly impact NOx emissions. The modified chambers controlled the spread of combustion and provided better fuel distribution, improving engine performance and combustion rates. The SCC (63.2 bar) showed peak pressure rates compared to the FCC (63.02 bar) and BTCC (62.72 bar). This study concluded that the SCC showed better results than other chambers. This study further recommends conducting lean fuel mixture combustion with chamber modifications and optimising fuel spray, such as by adjusting the fuel injection profile, spray angle and injection timing, which has a better tendency to create complete combustion.

Investigating the influence of varying split injection profiles on stability of diesel engine operated under partially premixed mode with methanol

The present study explores the prospects of operational stability of dual fuel operation comprehensively, considering that; methanol and diesel are of two different kinds which exhibit different combustion processes. To this effect, investigating the stability of engine operation under such condition becomes important. In this investigation, the harshness of the operation and the non-repeatability of the combustion cycles are examined, which have been identified as the major stability indicator in many studies. Such stability indices are characterized in this study through a comprehensive set of parameters, including of maximum pressure rise rate (ROPRmax) and coefficient of variation of indicated mean effective pressure (COVIMEP); and of peak pressure (COVPP) and crank angle of 50% mass fraction burn (COVCA50). The experimental investigation is carried out under a split injection strategy by varying injection timings as well as injection mass percentages at predefined methanol injection durations. It is shown that the partially premixed mode under the split injection strategy exhibits significant potential in reducing the harshness of operation indicated by lower peak pressure rise and increasing the repeatability of the combustion cycles implied by the substantially lower scores of the considered parameters for mapping stability.

Повышение эффективности глушения скважин на истощенных газоконденсатных месторождениях с сверх аномально низкими пластовыми давлениями

The problem is studied by the example of gas condensate fields at the final stage of development, where production wells have abnormally low reservoir pressures and their killing for repair work is a serious challenge requiring a search for new solutions. The work is motivated by the need to create a method for controlling hydrodynamic processes in a pre-blocked bottom-hole zone of the formation, for carrying out repair work in wells, preventing destruction of the reservoir formation and ensuring the preservation of its fluid-capacitance properties. The possibilities of an integrated approach to killing wells under conditions of extremely low formation pressures are considered, which includes controlling hydrodynamic processes in the “well-reservoir” system, previously blocked in the near-wellbore zone by special process fluids. It has been specified that the use of blocking fluids (with filler) helps to level the injectivity profile and form an insulating screen in the bottomhole zone of the formation, creating the necessary conditions for killing wells in order to carry out repair work in them. To control hydrodynamic processes, a mathematical model of the blocking process in the near-wellbore formation zone is proposed. It has a three-stage scheme that ensures equalization of the injectivity profile under conditions of extremely low formation pressures. The possibilities of using gel-forming blocking fluids with filler to create a temporary screen that prevents the penetration of killing fluid into highly permeable formations from abnormally low formation pressures have been explored. Based on the results of the study, we can conclude that the control of hydrodynamic processes in the near-wellbore zone of the formation at abnormally low formation pressures creates the necessary condition for effective blocking of the productive horizon in gas and gas-condensate wells, and due to the sequential treatment of the formation with a special liquid to level the injectivity profile and gel-forming blocking composition, allows one to kill the well and prevents the working fluid from penetrating into the depths of the formation during work.

Preparation of polymer microspheres as oil displacement agent for extra-high temperature and extra-high salinity reservoirs

Based on the difficult problem that conventional polymer and gel can't be used for enhancing oil recovery in extra-high temperature (200 °C) and extra-high salinity (2 ×105 mg/L) reservoirs，an anti-temperature anti-salinity microspheres was prepared with 2,2′-bis[4-(4-aminophenoxy)phenyl] propane (BAPP), 3, 3′, 4, 4′-diphenyl ether dianhydride (ODPA) and phthalic anhydride (PA) as the monomers. The FTIR results showed that the temperature- and salt-resistant polyimide (PI) microspheres were prepared as target product. TGA showed that thermal decomposition of the unaged and aged PI-2 microspheres occurred over 281 °C and 252 °C, respectively; These values greatly exceed those of commercial HPAM, weak gel particles and pre-crosslinked gel particles. After the polyimide microspheres were aged for 120 d, the enhanced oil recovery of the PI-2 microspheres does not decrease significantly, so the long-term stability of two polyimide microspheres are very good at 200 °C and total dissolved solids (TDS) = 2 × 105 mg/L. The PI-2 microspheres had better properties than the conventional polymer and gel as profile control agent and water plugging agent. The microspheres possess the characteristics of being able to inject, block, and move, resulting in excellent oil displacement efficiency. The results of core displacement experiments revealed that PI-2 microspheres are highly efficient in oil displacement and have a strong ability to improve the water injection profile. Therefore, PI-2 microspheres can be used as an oil displacement agent in reservoirs with extremely high temperature and salt content.

Anti-temperature anti-salinity nanospheres: Preparation, characterization, thermal stability, plugging ability and oil displacement

Based on the difficult problem that conventional polymer and gel can't be used for enhancing oil recovery in extra-high temperature (200 °C) and extra-high salinity (2 × 105 mg/L) reservoirs，an anti-temperature anti-salinity nanospheres was prepared with APB, ODPA and PA as the monomers. The results of FTIR showed the final products were target nanospheres. TG showed that thermal decomposition of the polyimide (PI-1) nanospheres occurred at 440 °C; these values greatly exceeded those of commercial HPAM, weak gel particles and pre-crosslinked gel particles. After the polyimide nanospheres were aged for 120 d, the enhanced oil recovery of the PI-1 nanospheres does not decrease significantly, so the long-term stability of two polyimide nanospheres are very good at 200 °C and TDS = 2 × 105 mg/L. The PI-1 nanospheres had better properties than the conventional polymer and gel as profile control agent and water plugging agent. The nanospheres have the characteristics of “able to inject, able to block, able to move”, and the oil displacement efficiency is very excellent. The results of core displacement experiments revealed that PI-1 microspheres had high oil displacement efficiency and strong ability to improve water injection profile. Therefore, the PI-1 microspheres can be used as oil displacement agent in extra-high temperature and extra-high salt reservoirs.

Impacts of vertical distribution of Southeast Asian biomass burning emissions on aerosol distributions and direct radiative effects over East Asia

The impacts of vertical distribution of biomass burning (BB) emissions on aerosol distributions and direct radiative effects over the BB source regions of Mainland Southeast Asia (MSEA) and downwind East Asian regions during spring (March to May) 2019 were investigated by applying an online coupled regional chemistry-aerosol-climate model (RIEMS-Chem). Model validation against a variety of observations demonstrated a generally good skill of the model in simulating aerosol chemical components, aerosol optical depth (AOD), and vertical distribution of aerosol extinction coefficient (EXT) when BB emissions were included. Four methods were adopted to represent injection height of BB emissions, including (1) a physical process-based parameterization (BB_param), (2) satellite-based prescribed profiles (BB_prof), (3) temporal-spatial varied injection profiles from the GFAS (Global Fire Assimilation System) dataset (BB_GFAS), and (4) BB emissions released at a fixed altitude (BB_high). The BB_param experiment generally produced better statistics compared to observations. Different BB injection height treatments considerably affected concentrations and distributions of BB aerosols, aerosol optical properties, direct radiative effects of BB aerosols (DREBB), atmospheric heating rate, and cloud fractions. The simulated sub-regional (100–120°E and 19–26°N, including major BB source and downwind areas) and seasonal mean DREBB at the top of the atmosphere (TOA) were +1.7 W m−2, +1.3 W m−2, +1.2 W m−2, and +1.7 W m−2 in the BB_param, BB_prof, BB_GFAS, and BB_high experiments, respectively, while the corresponding mean DREBB at the surface were −30.3 W m−2, -19.1 W m−2, -19.0 W m−2, and -22.1 W m−2. It is noticed that the DREBB at TOA and at the surface in BB_GFAS were just 68% and 63% of the values in BB_param, and the different injection height treatment had larger influences on DREBB at the surface than at TOA. The BB aerosol-induced atmospheric heating rate was up to 0.8–1.2 K/day in BB_param, which was larger than those in other experiments. Low cloud was enhanced while middle and high clouds were reduced by BB aerosols over northern MSEA. The BB aerosol-induced changes in cloud fractions in the BB_param experiment (up to 0.15 for low cloud and −0.05 for middle and high cloud) were approximately twice those in the other experiments. This study demonstrates the importance and necessity of properly representing the injection height of BB emissions in model estimation of radiative and climatic effects of BB aerosols.

Evaluation of Liquid Production and Water Injection Profiles of Horizontal Well by Pressure-Transient Analysis: Field Cases

Evaluation of Liquid Production and Water Injection Profiles of Horizontal Well by Pressure-Transient Analysis: Field Cases

New in the range of reagents and technologies for chemical enhanced oil recovery in high-temperature reservoirs

Currently, numerous enhanced oil recovery reagents and application technologies have been developed in the domains of flow rejection and injection profile levelling. The choice of stimulation methods is reliant on the geological and physical conditions of the reservoir. Therefore, the accuracy of this choice has a direct impact on the efficiency of implementing enhanced oil recovery technologies.The current availability of low-volume chemical enhanced oil recovery reagents for high-temperature reservoirs is limited, and their effectiveness varies. This article presents the results of a pilot study from 2018 to 2021 aimed at improving oil recovery in high-temperature reservoirs. The study involves evaluating approved levelling technologies for injection profiles that use thermotropic compositions "Complex 377" and "EOR701R", as well as the polymer composition "EOR909R". The geological and physical conditions of their approbation, as well as the primary injection parameters and resulting findings, are provided.This information will be valuable to professionals engaged in enhanced oil recovery methods for oil reservoirs, as well as those working on the implementation of physical and chemical methods for the same purpose.

Development and Application of Polymer Plugging Remover for Polymer Injection Well in Changqing Oilfield

Water injection is a conventional method to maintain reservoirs pressure and improve production in low permeability oilfield. To decrease high water-cut and further enhance oil recovery, Polymers, such as polymer microsphere, preformed polymer gel, cross-linked polyacrylamide, are extensively used to control injection profile in Changqing oilfield. However, due to the low permeability and narrow pore throats of tight reservoirs, pressure in some water flooding wells increases rapidly after the polymer was injected, negatively affecting the energy supplement of the well cluster. A polymer plugging remover, composed of oxidizer, acid and chelating agent to relieve blockage, was developed with viscosity reduction and structure decomposition. The release period is more than 48 hours, which is conducive to deep-seated plugging removal. After treatment, the average diameter of polymer residue is 39-254nm and the dissolution rate is 15.76-53.42%. The permeability of the core sample plugged with polymer has increased significantly before and after treatment by polymer plugging remover, especially, it recovered by 28.67% for microsphere polymer. Five field tests have been completed successfully in the Jiyuan oilfield of Changqing. Before treatment, conventional acidification was performed in the pilot wells for two times at least, which is proved invalid. However, after polymer degraded by the plugging remover, the injection rate increased by 16.2m3/d, the pressure dropped by 3.4MPa and the validity period has exceeded 130 days on average. The polymer plugging remover provides an alternative way to increase injectability when dealing with high pressure and under-injection wells caused by polymer flooding.