bluuebunny/crossref_metadata_2025 huggingface dataset:
Glycine for Enhanced Water Imbibition in Carbonate Reservoirs – What is the Role of Amino Group?
Authors: Baghishov Ilgar , Abeykoon Gayan A. , Wang Mingyuan , Argüelles Vivas Francisco J. , Okuno Ryosuke
Published: September 2021

Previous studies indicated the efficacy of the simplest amino acid, glycine, as an aqueous additive for enhanced water imbibition in carbonate reservoirs. The objective of this research was to investigate the importance of the amino group of glycine in its enhanced water imbibition. To this end, glycine was compared with two carboxylates (acetate and formate) with/without adding hydrogen chloride (HCl) for adjusting the solution pH. Note that the amino group is the only difference between glycine and acetate.

Contact-angle experiments on calcite were carried out at 347 K and atmospheric pressure with 68000-ppm reservoir brine (RB), and 4 different concentrations of glycine, acetate, and formate solutions in RB. To test the hypothesis that calcite dissolution is one of the main mechanisms in wettability alteration by glycine, we performed another set of contact angle experiments by adding HCl to brine, acetate, and formate solutions. HCl was added to match the pH of the glycine solution at the same concentration. We also performed imbibition tests with Texas Cream Limestone cores at 347 K with brine, glycine, acetate, and formate solutions (with and without HCl) in RB at 5.0 wt%.

Contact-angle results indicated that glycine changed calcite's wettability from oil-wet to water-wet (45°). However, acetate solution was not able to change the wettability to water-wet; and formate moderately decreased the contact angle to 80°. The pH level increased from 6.1 to 7.6 after the contact angle experiment in glycine solution, indicating the consumption of hydrogen ions due to calcite dissolution. The levels of pH in formate and acetate solutions, however, decreased from 8.4 to 7.8. The acidity of glycine above its isoelectric point arises from the deprotonation of the carboxyl group.

Imbibition tests with carbonate cores supported the observations from the contact-angle experiments. The oil recovery was 31% for glycine solution, 20% for RB, 21% for formate solution, and 19% for acetate solution. This re-confirmed the effectiveness of glycine as an additive to improve the oil recovery from carbonates. An additional set of imbibition tests revealed that acetate at the pH reduced to the same level as glycine was still not able to recover as much oil as glycine. This showed that glycine recovered oil not only because of the calcite dissolution and the carboxyl group, but also because of the amino group. It is hypothesized that the amino group with its electron donor ability creates a chelation effect that makes glycine entropically more favorable to get attached to the calcite surface than acetate.

Another important result is that the formate solution at an adjusted pH resulted in a greater oil recovery than RB or RB at the same pH. This indicates that there is an optimal pH for the carboxyl group to be effective in wettability alteration as also indicated by the pH change during the contact-angle experiment.
Advanced Gas While Drilling GWD Comparison with Pressure Volume Temperature PVT Analysis to Obtain Information About the Reservoir Fluid Composition, a Case Study from East Kuwait Jurassic Reservoir
Authors: Ahsan Mohammad J. , Al-Turkey Shaikha , Rane Nitin M. , Snasiri Fatemah A. , Moustafa Ahmed , Benyounes Hakim
Published: September 2021

Objectives/Scope

The acquisition of mud gas data for well control and gathering of geological information is a common practice in oil and gas drilling. However, these data are scarcely used for reservoir evaluation as they are presumably considered as unreliable and non-representative of the formation content.

Recent development in gas extraction from drilling mud and analyzing equipment has greatly improved the data quality. Combined with proper analysis and interpretation, these new datasets give valuable information in real-time lithological changes, hydrocarbons content, water contacts and vertical changes in fluid over a pay interval.

Methods, Procedures, Process

Post completion, Mud logging data have been compared with PVT results and they have shown excellent correlation on the C1-C5 composition, confirming the consistency between gas readings and reservoir fluid composition. Having such information in real time has given the oil company the opportunity to optimize its operations regarding formation evaluation, e.g downhole sampling, wireline logging or testing programs.

Formation fluid is usually obtained during well tests, either by running downhole tools into the well or by collecting the fluid at surface. Therefore, its composition remains unknown until the arrival of the PVT well test results. This case intends to use mud gas information collected while drilling to predict information about the reservoir fluid composition in near real time. To achieve this goal we compared mud gas data collected while drilling with reservoir fluid compositional results.

Pressure volume temperature (PVT) analysis is the process of determining the fluid behaviors and properties of oil and gas samples from existing wells.

Results, Observations, Conclusions

The reason any oil and gas company decides to drill a well is to turn the project into an oil-producing asset. But the value of the oil extracted from a single well is not the same as the value of the oil produced from another. The makeup of the oil, which can be determined from the compositional analysis, is an important piece of the equation that determines how profitable the play will be. The compositional analysis will determine just how much of each type of petroleum product can be produced from a single barrel of oil from that wells.

Novel/Additive information

Formation samples were obtained from offset wells in the Marrat Formation. These datasets gave valuable indications on fluid properties and phase behavior in the reservoir and provided strong base for reservoir engineering analysis, simulation and surface facilities design.

The comparison of the gas data to PVT results gives a good match for reservoir fluid finger print, early acquisition of this data will help for decision enhancement for field development.
Suppression Performance of an Unmodified Bio-Extract for Simulated Offshore Gas Hydrate Mitigation
Authors: Wachikwu-Elechi Virtue Urunwo , Ikiensikimama Sunday Sunday , Ajienka Joseph Atubokiki , Akaranta Onyewuchi Emmanuel , Okon Okon Efiong
Published: September 2021

Gas hydrate inhibition through the use of chemicals has been ongoing over the years and these chemicals are toxic, synthetic and expensive, adding to the cost of doing oil and gas business, and also leads to environmental degradation. The call for greener environment has necessitated the search for more eco-friendly gas hydrate inhibitors. This paper takes a look at the use of a bio-extract in its unmodified state to inhibit gas hydrate using a locally made mini flow loop for gas hydrate studies. The bio extract was compared to a conventional gas hydrate inhibitor 2-Di(methylaminoethyl)methacrylate (2-DMAEM). For all the weight percentages considered (0.01-0.05wt%), the bio-extract had better pressure profiles. At the end of the experiment which lasted for 120 minutes, this is attributed to the fact that the pressures in the system were more regulated which prevented rapid gas dissolution in water. The Bio-extract is plant based, locally available in the commercial quantity and is eco-friendly so it should be harnessed as gas hydrate inhibitors in lieu of the expensive and imported conventional hydrate inhibitor 2-DMAEM which non-eco-friendly.
ESP and Completion Deployment using Dual Derrick Drill Ship Rigs
Authors: Lemos Daniel , Marins Jean , De Lima Raone
Published: September 2021

This paper presents an innovative concept to run Electrical Submersible Pumps (ESP) and upper completion utilizing dual derrick drillship rigs in deep water wells. The availability of a second deck to assemble, test and rack long assemblies brings the possibility to conduct a safer, efficient and reliable operation. The experience in Brazil running complex completions and high horsepower ESPs shows how important is to implement initiatives to reduce rig time. The main objective of the new process is to have every completion tool readily available in the drilling deck, requiring minimum time to connect it to the completion string. In the standard process, the tool sits in the pipe deck until completion string reaches its set position and only then the equipment is brought into the rig floor to be serviced and made up to the completion string. The methodology to assemble ESP and completion tools offline in the auxiliary derrick was developed in partnership with the operator, the service company, and the drilling rig contractor.

The offline preparation concept was considered as part of the completion design phase analyzing every step of the upper completion run, looking for efficiency improvement and reduced total rig time.

The modern automated pipe handling system was used to manipulate the long and heavy assemblies from the auxiliary deck to the racking system and from the racking system to the main deck without any safety concern, and with minimal human intervention.

Eight deep-water operations were completed in Brazil using the new concept and the results brought important rig time reduction in the upper completion running time. The tools that were part of the completion included DHSV, permanent downhole gauges, chemical injection valves, 1600 HP ESP system and tubing test valves. The new process allows the team to service equipment without the usual operation rush reducing installation related failure therefore increasing equipment reliability.

The methodology presented on this paper contributes to oil industry as a field-proven reference for offshore ESP and completion deployment technique reducing HSE exposure and total well construction cost. This is particularly important for deep and ultra-deepwater projects which are associated with high intervention costs. Dual derrick rigs were designed with focus to improve drilling operations and after the new process development, the modern robotized machinery empowers ESP and completion activities with improved efficiencies.
Fluid Cool Down vs. Heat Back - An Analysis of Bottomhole Gauge Temperature Responses to Optimize Stimulation Fluid Clean Up and Thereof Testing, Offshore Black Sea
Authors: Grubac Gabrijel , Patrascu Radu , Precupanu Laura
Published: September 2021

In an effort of maximizing the production from low permeability reservoirs in mature fields, operators often strive to implement innovative technologies and engineering approaches that can help achieve that goal. This paper presents an analysis of the temperature responses from bottom hole gauges of several horizontal wells that have been stimulated offshore Black Sea. The analysis covers the fluid cool down and heat back profile during stimulation and production. Ultimately, the analysis’ goal being to better understand the rheological properties of the stimulation fluid and enhance well clean-up by avoiding miss-allocation of temperature ranges during fluid testing for when the well is brought on production. Based on available data from bottom hole gauges implemented in the horizontal wells stimulated in the Black Sea, an analysis of the temperature gauge responses has been performed. The analysis includes a workflow of temperature change validation per well, considering fluid pumped per port in stimulation phase and fluids produced per port in production phases. The fluid production allocation per port was done utilizing chemical tracer technology results.

Stimulation treatments in the same reservoir offshore Black Sea, Romania have been analyzed in terms of bottom hole gauge readings of temperature during the stimulation fluid pumping and during the early production period of each well. A workflow was implemented on each well to correlate fluid per stimulation stage pumped to temperature changes during the treatments. Similar approach was used to correlate the temperature heat back profile during the shut in of wells in the initial 48 hours for proppant curing to the production phase clean-up of the wells. The observed cool down during pumping was of no surprise, but the heat back indicated a slower process of warm back that affects the stimulation fluid testing approach and the understanding of possible near wellbore pressure differentials caused by misallocation of temperature range testing of pre job rheology tests. A combination of temperature data with diagnostic tools and the pertaining analysis will provide a better description of wells’ performance.

In conclusion, misinterpretation of modelled cool down and reservoir heat back can lead to erroneous understanding of fluid clean up, ultimately affecting reservoir fluid inflow. Understanding the areal temperature response helped optimize fluid testing approach and plan for better clean up.

The approach and the sensitivity analysis results are beneficial in understanding the temperature behavior during treatment pumping and production of stimulated wells. This process can enhance an engineer's approach in scrutinizing stimulation fluid testing for improved post stimulation clean up.
Photoacoustic Nanotracers for Subsurface Applications: Opportunities and Challenges
Authors: Felix Servin Jesus Manuel , Al-Sadeg Hala A. , Abdel-Fattah Amr
Published: September 2021

Tracers are practical tools to gather information about the subsurface fluid flow in hydrocarbon reservoirs. Typical interwell tracer tests involve injecting and producing tracers from multiple wells to evaluate important parameters such as connectivity, flow paths, fluid-fluid and fluid-rock interactions, and reservoir heterogeneity, among others. The upcoming of nanotechnology enables the development of novel nanoparticle-based tracers to overcome many of the challenges faced by conventional tracers. Among the advantages of nanoparticle-based tracers is the capability to functionalize their surface to yield stability and transportability through the subsurface. In addition, nanoparticles can be engineered to respond to a wide variety of stimuli, including light.

The photoacoustic effect is the formation of sound waves following light absorption in a material sample. The medical community has successfully employed photoacoustic nanotracers as contrast agents for photoacoustic tomography imaging. We propose that properly engineered photoacoustic nanoparticles can be used as tracers in oil reservoirs. Our analysis begins by investigating the parameters controlling the conversion of light to acoustic waves, and strategies to optimize such parameters. Next, we analyze different kind of nanoparticles that we deem potential candidates for our subsurface operations. Then, we briefly discuss the excitation sources and make a comparison between continuous wave and pulsed sources. We finish by discussing the research gaps and challenges that must be addressed to incorporate these agents into our operations.

At the time of this writing, no other study investigating the feasibility of using photoacoustic nanoparticles for tracer applications was found. Our work paves the way for a new class of passive tracers for oil reservoirs. Photoacoustic nanotracers are easy to detect and quantify and are therefore suitable for continuous in-line monitoring, contributing to the ongoing real-time data efforts in the oil and gas industry.
Preventing Asphaltene Deposition by Inhibitor Squeeze Injection: Case Studies from Giant Carbonate Abu Dhabi Fields
Authors: Punnapala Sameer , Abdullah Dalia Salim , Grutters Mark , Cristea Zaharia , El Naggar Hossam El Din Mohamed , Bahamish Fatima Jamal , Senaad Rabah , Bakri Hasan Jamil , Abbas Zafar
Published: September 2021

Asphaltene deposition is a notorious flow assurance problem faced by oil companies that causes production loss and large expenses for operators. The complex nature of asphaltenes and limited data available makes it challenging to develop a full field implementation strategy that is economically viable as well. Conducting asphaltene clean-up operations whenever wells get plugged up are the reactive approach to deal with asphaltene issues. However these approaches often result in prolonged well downtime, production losses and high well intervention costs. As part of proactive measures, chemical inhibitors were screened for formation squeeze and field trials conducted to assess their performance. Results from these trials helped to frame the full-field implementation strategy that is promising from a technical-economic standpoint. This paper describes the asphaltene mitigation journey of a major Abu Dhabi oil operator that resulted in multi-million dollar savings.
Surfactant-Polymer Formulations for EOR in High Temperature High Salinity Carbonate Reservoirs
Authors: Sotomayor Mauricio , Alshaer Hassan , Chen Xiongyu , Panthi Krishna , Balhoff Matthew , Mohanty Kishore
Published: September 2021

Harsh conditions, such as high temperature (>100 oC) and high salinity (>50,000 ppm TDS), can make the application of chemical enhanced oil recovery (EOR) challenging by causing many surfactants and polymers to degrade. Carbonate reservoirs also tend to have higher concentrations of divalent cations as well as positive surface charges that contribute to chemical degradation and surfactant adsorption. The objective of this work is to develop a surfactant-polymer (SP) formulation that can be injected with available hard brine, achieve ultra-low IFT in these harsh conditions, and yield low surfactant retention. Phase behavior experiments were performed to identify effective SP formulations. A combination of anionic and zwitterionic surfactants, cosolvents, brine, and oil was implemented in these tests. High molecular weight polymer was used in conjunction with the surfactant to provide a high viscosity and stable displacement during the chemical flood. Effective surfactant formulations were determined and five chemical floods were performed to test the oil recovery potential. The first two floods were performed using sandpacks from ground Indiana limestone while the other three floods used Indiana limestone cores. The sandpack experiments showed high oil recovery proving the effectiveness of the formulations, but the oil recovery was lower in the cores due to complex pore structure. The surfactant retention was high in the sandpacks, but it was lower in Indiana Limestone cores (0.29-0.39 mg/gm of rock). About 0.4 PV of surfactant slug was enough to achieve the oil recovery. A preflush of sodium polyacrylate improved the oil recovery.
Experimental Investigation of Two-Phase Flow Properties of Heterogeneous Rocks for Advanced Formation Evaluation
Authors: Aérens Pierre , Torres-Verdín Carlos , Espinoza D. Nicolas
Published: September 2021

An uncommon facet of Formation Evaluation is the assessment of flow-related in situ properties of rocks. Most of the models used to describe two-phase flow properties of porous rocks assume homogeneous and/or isotropic media, which is hardly the case with actual reservoir rocks, regardless of scale; carbonates and grain-laminated sandstones are but two common examples of this situation. The degree of spatial complexity of rocks and its effect on the mobility of hydrocarbons are of paramount importance for the description of multiphase fluid flow in most contemporary reservoirs. There is thus a need for experimental and numerical methods that integrate all salient details about fluid-fluid and rock-fluid interactions. Such hybrid, laboratory-simulation projects are necessary to develop realistic models of fractional flow, i.e., saturation-dependent capillary pressure and relative permeability.

We document a new high-resolution visualization technique that provides experimental insight to quantify fluid saturation patterns in heterogeneous rocks and allows for the evaluation of effective two-phase flow properties. The experimental apparatus consists of an X-ray microfocus scanner and an automated syringe pump. Rather than using traditional cylindrical cores, thin rectangular rock samples are examined, their thickness being one order of magnitude smaller than the remaining two dimensions. During the experiment, the core is scanned quasi-continuously while the fluids are being injected, allowing for time-lapse visualization of the flood front. Numerical simulations are then conducted to match the experimental data and quantify effective saturation-dependent relative permeability and capillary pressure.

Experimental results indicate that flow patterns and in situ saturations are highly dependent on the nature of the heterogeneity and bedding-plane orientation during both imbibition and drainage cycles. In homogeneous rocks, fluid displacement is piston-like, as predicted by the Buckley-Leverett theory of fractional flow. Assessment of capillary pressure and relative permeability is performed by examining the time-lapse water saturation profiles. In spatially complex rocks, high-resolution time-lapse images reveal preferential flow paths along high permeability sections and a lowered sweep efficiency.

Our experimental procedure emphasizes that capillary pressure and transmissibility differences play an important role in fluid-saturation distribution and sweep efficiency at late times. The method is fast and reliable to assess mixing laws for fluid-transport properties of rocks in spatially complex formations.
Boosting Production in the Llanos Orientales Colombia Basin, with an Approach to the Usage of the Completion Fluid. A Recent Case Study
Authors: Diaz Lozano Carlos Mario , Cortes Daza Carlos Andres , Pacheco Gomez Erika Andrea , Plata Ruiz Elizabeth , Castellanos Carvajal Jaime
Published: September 2021

This arcticle highlights the importance of a systematic step change approach to the formulation of completion fluids in the Llanos Basin (LLAB), Colombia, when formation-freshwater is to be used as control - completion (C&C) fluid. The results demonstrate that the process used reduced the formation damage statistics from 41% of the wells drilled to only 16%, boosting production and establishing a best practice for future drilling and completion (D&C) campaigns in the region.

An initial sample of 19 wells was considered to evaluate the damage caused by using formation-freshwater as C&C fluid. Formation-freshwater was selected only considering the fluid density (wellbore pressure), ignoring the negative effects it can have on formation damage. 41% of the wells were damaged, as evidenced by pressure build up. Some of the main damages on the pay-zone in an oil well are due to emulsion blocking, change in wettability, swelling and migration of clays, incompatibility of fluids, and scale formation. A detailed design of completion fluids has a positive influence over well productivity by mitigating formation damage before starting the production stage. The methodology used was aimed at designing the C&C fluid through a step-by-step approach, consisting of: 1) Laboratory tests supported with mineralogical data and oil and formation water properties and 2) Physical-chemical analysis of reservoir fluids and water for mixing purposes. The process involved testing different formulations and then their implementation in the field. The initial tests were conducted in a total of 5 wells in 4 fields. Changes were identified in the formulation to achieve optimal fluid design for each field and then the selected fluid was extended to a total of 24 wells. This was the first time a thoroughly designed completion fluid was used in the region.

The results point towards the need to include surfactants, mutual solvents, and brines to substantially reduce formation damage. The application of new completion fluids enabled the operational teams to optimize the process by steps. The implementation of customized completion fluid reduced the formation damage as evidenced through productivity analyses and pressure build up tests. Only 16% of the wells presented formation damage.

The process applied to reduce formation damage of the Llanos Basin led to a systematic approach for the analysis stage, which may be applied in other areas, where the utilization of formation-freshwater is an issue. The particularly short time frames and best practices derived from the learning curve of this case are worth to be shared with other operators.
Exploiting Natural Nonconservative Geochemical Data to Obtain Reservoir Information
Authors: Wang Yanqing , Liu Zhe , Zhang Yuchen , Lu Jun
Published: September 2021

Geochemical data in produced water contain important reservoir information but are seldomly exploited, especially for the nonconservative chemicals. Some conservative chemical data have been integrated in history matching workflow to obtain better knowledge of reservoirs. However, assuming reservoir chemicals being conservative is impractical because most chemicals are involved in interactions with other chemicals or reservoir rock, and mistakenly regarding nonconservative chemicals as being conservative can cause large error. Nevertheless, once the interactions can be accurately described, nonconservative chemical data can be used to obtain more reservoir information. In this work, a new physicochemical model is proposed to describe the transport of natural nonconservative chemicals (barium and sulfate) in porous media. Both physical reactions, such as ion adsorption and desorption, and chemical reactions, such as barite deposition, are integrated. Based on the new model, the ensemble smoother with multiple data assimilations (ES-MDA) method is employed to update reservoir model parameters by assimilating oil production rate, water production rate, and chemical data (barium and sulfate concentration). Data assimilation results show that integrating geochemical data in ES-MDA algorithm yields additional improvements in estimation of permeability. Besides, clay content distribution, which is critical in injection water breakthrough percentage calculation, can be accurately estimated with relative root mean square error (rRMSE) being as small as 0.1. However, mistakenly regarding nonconservative chemicals as conservative can cause large errors in reservoir parameters estimation. Accurately modeling the chemical interactions is crucial for integrating chemical data in history matching algorithm.
Asset of the Future - Comprehensive Business Transformation Program
Authors: Sitnikov Alexander , Doktor Sergei , Margarit Andrei
Published: September 2021

In the recent years the oil and gas industry has started facing an unprecedented number of challenges. The average return on capital in the industry has deteriorated which results in investor mistrust and costs being higher than ever. Debt capital became two times costlier than for alterative types of energy. More conventional oilfields become depleted and new reserves are usually quite complex to develop. These and other challenges such as intense competition between oil and gas companies, the energy transition agenda as well as the volatility of oil prices in the aftermath of the pandemic are pushing the O&G companies to transform themselves.

Gazprom Neft introduced the "Asset of the Future" program in late 2018 as a timely response which was aimed at completely transforming the Upstream business model. The main issue with the transformation was the scale of it, which included 10 subsidiaries (or subs) and more than 200 different processes. In this case traditional approaches such as improving each operation one by one would not suffice as the company sought a rapid and highly efficient implementation of changes. As such the program had to develop a new approach that focused on the integration of all business parts and continuous improvement. Integration of people, technology and processes will lead to better collaboration and as a result - to smarter decisions and better execution.
Pretreatment of Produced Waters Containing High Total Dissolved Solids
Authors: Kaishentayev Damir , Hascakir Berna
Published: September 2021

There are mainly two types of solids in the oil field waters; Suspended Solids (SS) and Total Dissolved Solids (TDS). While it is easy to remove SS from water, removal of TDS requires the application of advance filtration techniques such as reverse osmosis or ultra-filtration. Because these techniques cannot handle high volumes of the oilfield waters with high TDS content, produced waters originated from hydraulic fracturing activities cannot be treated by using these advance technologies. Thus, in this study we concentrated on the pretreatment of these waters.

We investigated the feasibility of the Coagulation, Flocculation, and Sedimentation (CFS) process as pretreatment method to reduce mainly SS in Produced Water (PW) samples. We collected samples from 14 different wells in the Permian Basin. First, we characterized the water samples in terms of pH, SS, TDS, Zeta potential (ZP), Turbidity, Organic matter presence and different Ion concentration. We tested varying doses of several organic and inorganic chemicals, and on treated water samples we measured pH, TDS, SS, Turbidity, ZP and Ions. Then, we compared obtained results with the initial PW characterizations to determine the best performing chemicals and their optimal dosage (OD) to remove contaminants effectively.

The cation and anion analyses on the initial water samples showed that TDS is mainly caused by the dissolved sodium and chlorine ions. ZP results indicated that SS are mainly negatively charged particles with absolute values around 20 mV on average. Among the tested coagulants, the best SS reduction was achieved through the addition of ferric sulfate, which helped to reduce the SS around 86%. To further lessen SS, we tested several organic flocculants in which the reduction was improved slightly more.

We concluded while high TDS in the Permian basin does not implement a substantial risk for the reduction of fracture conductivity, SS is posing a high risk. Our study showed, depending on components of the initial PW, reuse of the pretreated water for fracturing may minimize fracture conductivity damage.
Chelating Agents as a Stimulation Fluid with a Negative Reaction Order: More Diluted Solutions React Faster with Carbonates
Authors: Ivanishin Igor , Samouei Hamidreza
Published: September 2021

Chelating agents are used to stimulate high-temperature carbonate reservoirs and remove mineral scales. For field applications, commercial chelates—EDTA, DTPA, GLDA, etc.—are commonly supplied as 35–50 wt% (1.2–1.7 M) solutions and diluted two times in water. However, the dependence of the reaction rate on the concentration of chelate in solution has never been quantified. This paper focuses on determining the kinetics of calcite dissolution as a function of the dilution factor of commonly used chelates at acidic pH. Using a rotating disk apparatus, the kinetics of calcite marble dissolution in 0.1–0.25 M EDTA (pH=4.9–5.0), 0.1–0.25 M DTPA (pH=3.5–5.0), and 0.28–0.85 M GLDA (pH=3.7–5.0) solutions has been investigated. The dissolution of calcite in all chelates has a negative fractional-order that increases with temperature in the range -0.6 < n < -1.9. Thus, less concentrated chelate solutions react faster with calcite, and the effect of chelate dilution becomes less pronounced with a temperature increase. For example, three times dilution of pH≈3.7 commercial GLDA solution—from commonly used 50 vol% (0.85 M) to 16.7 vol% (0.28 M)—increases calcite dissolution rate 8.4, 4.9, 2.7, and 2.0 times at 98.6, 116.6, 134.6, and 188.6°F, respectively. Dilution of pH=5.0 EDTA and pH=3.5 DTPA from 0.25 M to 0.1 M increases the dissolution rate of calcite 1.4–3.1 times at 98.6–188.6°F. Probable reasons for such an unusual reaction behavior are discussed in the paper. Presented results are integral for designing the stimulation operations in carbonate reservoir rocks and the removal of carbonate scales.
Investment Strategy of CO2-EOR in China: Analysis Based on Real Option Approach
Authors: Bi Jianfei , Li Jing , Chen Zhangxin John , Gao Yanling , Liu Yishan , Wu Keliu , Dong Xiaohu , Feng Dong , Zhang Shengting
Published: September 2021

As the most potential Carbon Capture, Utilization, and Storage (CCUS) technology, CO2-enhanced oil recovery (CO2-EOR) can both improve oil recovery and relieve the pressure of reducing CO2 emission. However, CO2-EOR projects have not been substantially deployed in China due to the significant investment and high uncertainties of technology, market, and policy. Therefore, identifying potential bottlenecks, and developing effective investment strategies are of great necessity at present. In this work, a real option approach combined with reservoir simulation technologies is proposed, which can investigate the optimal deployment timing and the investment value of the CO2-EOR projects. Meanwhile, a sensitivity analysis is conducted to examine the effects of different uncertainties. The results show that real option approach is suitable for the evaluation of CO2-EOR projects because it can fully take the flexibility of investment time into account. And it is found that under the current investment environment, it is difficult for China to deploy CO2-EOR projects on a large scale before 2030. High oil prices, low CO2 purchase prices, and transportation of CO2 by pipeline can bring forward the investment time and increase the investment value. Besides, government subsidies and technological progress are also favorable for the deployment of the project. Compared with technological progress, the effect of subsidies is more obvious, while it should be noted that huge subsidies will bring a financial burden to the government. In a word to launch CO2-EOR projects earlier and make it play a more important role in China's carbon emission reduction, a compound strategy should be made based on consideration of all these influencing factors.
Steady-State Liquid Permeability Measurements in Samples from the Bakken Formation, Williston Basin, USA
Authors: Ramiro-Ramirez Sebastian , Flemings Peter B. , Bhandari Athma R. , Jimba Oluwafemi Solomon
Published: September 2021

We measured steady-state liquid (dodecane) permeability in four horizontal core plugs from the middle member of the Bakken Formation at multiple effective stress conditions to investigate how permeability evolves with confining stress and to infer the matrix permeability. Three of the four tested samples behaved almost perfectly elastically as the hysteresis effect was negligible. In contrast, the fourth sample showed a permeability decrease of ~40% at the end of the test program. Our interpretation is that the closure of open artificial micro-fractures initially present in the sample (based on micro-CT imaging) caused that permeability hysteresis. The matrix permeability to dodecane (oil) of the tested samples is between ~50 nD and ~520 nD at the confining pressure of 9500 psi. The 520 nD sample exhibited the lowest porosity, the highest calcite content, and the largest dominant pore throat radii. In contrast, the 50 nD sample was more porous, and exhibited the highest dolomite content and the smallest dominant pore throat radii. This study shows that our multi-stress testing protocol allows the study of the permeability hysteresis effect to interpret the matrix permeability. We also document the presence of middle Bakken lithologies with permeabilities up to one order of magnitude greater than others. These permeable lithologies may have a significant contribution to well production rates.
Reconstruction and Synthesis of Source Rock Images at the Pore Scale
Authors: Anderson Timothy
Published: September 2021

Image-based characterization of rock fabric is critical for understanding recovery mechanisms in shale formations due to the significant multiscale nature of shale source rocks. Nanoscale imaging is particularly important for characterizing pore-scale structure of shales. Nanoimaging techniques, however, have a tradeoff between high-resolution/high-contrast sample-destructive imaging modalities and low-contrast/low-resolution sample-preserving modalities. Furthermore, acquisition of nanoscale images is often time-consuming, expensive, and requires signficant levels of expertise, resulting in small image datasets that do not allow for accurate quantification of petrophysical or morphological properties. In this work, we introduce methods for overcoming these challenges in image-based characterization of the fabric of shale source rocks using deep learning models. We present a multimodal/multiscale imaging and characterization workflow for enhancing non-destructive microscopy images of shale. We develop training methods for predicting 3D image volumes from 2D training data and simulate flow through the predicted shale volumes. We then present a novel method for synthesizing porous media images using generative flow models. We apply this method to several datasets, including grayscale and multimodal 3D image volume generation from 2D training images. Results from this work show that the proposed image reconstruction and generation approaches produce realistic pore-scale 3D volumes of shale source rocks even when only 2D image data is available. The models proposed here enable new capabilities for non-destructive imaging of source rocks and we hope will improve our ability to characterize pore-scale properties and phenomena in shales using image data.
Comparative two-dimensional fluorescence gel electrophoresis
Authors: König Simone , Ackermann Doreen
Published: September 2021

Comparative two-dimensional gel electrophoresis (CoFGE) is a special version of two-dimensional polyacrylamide GE (2D-PAGE) and related to difference GE (2D-DIGE). It provides reproducibility and standardisation for 2D-PAGE by introducing a reference to the experiment. CoFGE uses different fluorescent labels to distinguish analyte and a marker protein mixture. The method allows in silico correction of the assignment of gel-separated proteins based on the co-run references, which form a grid of landmarks across the entire gel. The variability of spot coordinates is reduced to ~1% error and data can thus be compared to results generated independently with the same method. In this way, searchable repositories of gel-separated proteins become feasible. In addition, the CoFGE experimental principle can be used for protein quantification by applying the proteins of the marker grid in different concentrations. Here we present the protocol for conducting a CoFGE experiment, which takes about 2 days to complete for a technician skilled in GE.
Autoimmune myelofibrosis associated with autoimmune hemolytic anemia successfully treated with ruxolitinib
Authors: Sato Shuku , Kamata Wataru , Tamai Yotaro
Published: September 2021

A 55-year-old man suffered from dyspnea, general malaise, and jaundice. His laboratory date showed pancytopenia and hemolytic anemia, and computed tomography showed splenomegaly. Bone marrow examination revealed myelofibrosis (MF)-1. The hemolytic anemia was diagnosed as IgM autoimmune hemolytic anemia (AIHA) with negative direct and indirect Coombs test but positive IgM-direct antiglobulin test. We started ruxolitinib 20 mg, which improved not only bone marrow fibrosis, symptoms related to myeloproliferative neoplasms and splenomegaly, but also AIHA. AIHA may be associated with Autoimmune MF (AIMF), and cytokines such as transforming growth factor (TGF)-β are thought to be involved in such cases. This case suggests that ruxolitinib may improve the cytokine levels and may lead to the treatment of AIHA as well as AIMF.
TBX15/miR-152/KIF2C Pathway Regulates Breast Cancer Doxorubicin Resistance Via Promoting PKM2 Ubiquitination
Authors: Jiang Cheng-Fei , Xie Yun-Xia , Qian Ying-Chen , Wang Min , Liu Ling-Zhi , Shu Yong-Qian , Bai Xiaoming , Jiang Bing-Hua
Published: September 2021

Background: Chemoresistance is a critical risk problem for breast cancer treatment. However, mechanisms by which chemoresistance arises remains to be elucidated. The expression of T-box transcription factor 15 (TBX-15) was found downregulated in some cancer tissues. However, role and mechanism of TBX15 in breast cancer chemoresistance is unknown. Here we aimed to identify the effects and mechanisms of TBX15 in doxorubicin resistance in breast cancer.Methods: As measures of Drug sensitivity analysis, MTT and IC50 assays were used in DOX-resistant breast cancer cells. ECAR and OCR assays were used to analyze the glycolysis level, while Immunoblotting and Immunofluorescence assays were used to analyze the autophagy levels in vitro. By using online prediction software, luciferase reporter assays, co-Immunoprecipitation, Western blotting analysis and experimental animals models, we further elucidated the mechanisms.Results: We found TBX15 expression levels were decreased in Doxorubicin (DOX)-resistant breast cancer cells. Overexpression of TBX15 reversed the DOX resistance by inducing microRNA-152 (miR-152) expression. We found that KIF2C levels were highly expressed in DOX-resistant breast cancer tissues and cells, and KIF2C was a potential target of miR-152. TBX15 and miR-152 overexpression suppressed autophagy and glycolysis in breast cancer cells, while KIF2C overexpression reversed the process. Overexpression of KIF2C increased DOX resistance in cancer cells. Furthermore, KIF2C directly binds with PKM2 for inducing the DOX resistance. KIF2C can prevent the ubiquitination of PKM2 and increase its protein stability. In addition, we further identified that Domain-2 of KIF2C played a major role in the binding with PKM2 and preventing PKM2 ubiquitination, which enhanced DOX resistance by promoting autophagy and glycolysis. Conclusions: Our data identify a new mechanism by which TBX15 abolishes DOX chemoresistance in breast cancer, and suggest that TBX15/miR-152/KIF2C axis is a novel signaling pathway for mediating DOX resistance in breast cancer through regulating PKM2 ubiquitination and decreasing PKM2 stability. This finding suggests new therapeutic target and/or novel strategy development for cancer treatment to overcome drug resistance in the future.
Analysis of TCP Transcription Factors Revealed Potential Roles in Plant Growth and Fusarium Oxysporum F.Sp. Cubense Tolerance in Banana (cv. Rasthali)
Authors: Chaturvedi Siddhant , Khan Shahirina , Usharani T. R. , Tiwari Siddharth
Published: September 2021

The TCP transcription factor gene family is highly conserved among the plant species. It plays a major role in the regulation of flower symmetry, cell division, development of leaf, fibre and nodule in the plants by controlling the synthesis of various plant hormones. Banana is a major staple crop in the world. However, Fusarium oxysporum f. sp. cubense (Foc) infection is a major threat to banana production. The role of TCP gene family during the Foc infection is not explored till now. Herein, a total of 27 non-redundant TCP (MaTCP) gene sequences were retrieved from the banana genome and analysed for structural characteristics, phylogenetic correlation, subcellular, and chromosomal localizations. Phylogenetic analysis showed that the MaTCP proteins were highly conserved among different species and found to be the closest relative of the Oryza sativa and Zea mays. Promoter analysis of the TCP sequences showed that the cis-acting regulatory elements are associated with various stresses, environmental and hormonal signals. The higher transcripts accumulation in developing tissues (fruit finger, leaves, and stem) than of mature tissues (peel and pulp) showed a significant role of MaTCP in banana (cv. Rasthali) growth and development. Further, higher expression of the certain MaTCPs (MaTCP2, MaTCP4, MaTCP6, MaTCP9 and MaTCP11) in Foc race 1 infected root and leaf tissues of Rasthali indicated their promising role during Fusarium infection. This study will underpin the facet of TCP transcription factors on the development of biotic (Foc) stress tolerance in banana.
Does Environmental Decentralization Improve Regional Green Innovation? Evidence from China
Authors: Yang Nana , Liu Qiming
Published: September 2021

Green innovation is critical for sustainable development. The reform of environmental management system plays an important role in improving environmental pollution and technology progress. Working from a heterogeneous perspective, this study investigates the effects of different types of environmental decentralization on regional green innovation using statistical data from 30 provinces in China over the period of 2000–2015. The results show that environmental decentralization (ED) promotes regional green innovation. Furthermore, according to different environmental management of levels and affairs, we divide environmental decentralization into provincial-level environmental decentralization (PED), municipal-level environmental decentralization (MED), and county-level environmental decentralization (CED); environmental administrative decentralization (EAD), environmental monitoring decentralization (EMD), and environmental supervision decentralization (ESD), respectively. There is also evidence suggesting that different types of environmental decentralization have varied effects on regional green innovation. These findings set out in this study are robust when different methods are employed. A further investigation indicates that the effects of different types of environmental decentralization on green innovation apparently differ across Chinese different regions. Some policy recommendations will help policymakers to determine more effective environmental decentralization.
Characterization of The Microbiome In Bile From Normal Human Gallbladders
Authors: Watanabe Shin , Shinoda Tadashi , Minagawa Masaaki , Toya Mari , Motooka Daisuke , Kirikae Teruo , Saiura Akio , Nakamura Shota
Published: September 2021

Background: Scientists previously believed that bacteria could not grow in bile, which is rich in bacteriostatic compounds such as bile acids. Therefore, the biliary tract was considered to be a sterile environment. However, high-throughput (i.e., amplicon) sequencing analysis methods have recently been used to discover the bacterial flora in gallbladder bile in brain-dead patients with normal gallbladders. In a bacterial flora analysis targeting the 16S ribosomal gene, a specific flora was present in the bile of normal gallbladders. However, these results were not obtained from truly healthy individuals. Therefore, the aim of this study was to analyze the microbial flora of bile collected from pathologically normal gallbladders that were surgically removed from patients with hepatobiliary pancreatic diseases who had normal liver function.Results: All 12 bile samples obtained from the gallbladders had negative culture results, although a bacterial flora was detected in all samples via 16S ribosome gene analysis. The composition of the bacterial flora was very simple, and the Firmicutes, Proteobacteria, and Actinobacteria phyla were identified in all samples. Based on 16S rRNA gene profile analysis, the composition ratio accounted for more than 80% of the total number of reads. The Anaerobacillus, Delftia, Bacillus, Ralstonia, Ochrobactrum, Acidovorax, and Curvibacter genera were detected in all 12 samples. Based on 16S rRNA gene profile analysis, at the genus level, Anaerobacillus and Delftia accounted for 58.62%–87.63% of the identified bacteria in each sample. Conclusions: In this study, the bacterial flora in the gallbladder bile was not diverse. Contrary to previous reports, few bacteria belonging to the Bacteroidetes phylum were detected. The functional significance of the gallbladder bacterial flora requires further investigation.