bluuebunny/crossref_metadata_2025 huggingface dataset:
Completion Effects on Diagnosing Multistage Fracture Treatments with Distributed Temperature Sensing
Authors: Sakaida Shohei , Zhu Ding , Hill A. D.
Published: October 2020

Distributed temperature sensing (DTS) is a valuable tool to diagnose multistage hydraulic fracture treatments. When a stage interval is shut-in, the clusters which take more fluid during pumping warm up more slowly. Therefore, the fluid volume injected into each cluster can be quantitatively interpreted by numerical inversion of the warm-back temperature behavior. This general concept assumes that the different warm-back behavior is controlled by only the injected fluid volume, however, recent observations of DTS data indicate that completion configurations significantly influence the warm-back behavior.

This paper investigates the completion effects on the DTS interpretation. In ideal conditions, when a stage is fractured, the upstream stage intervals should show an almost uniform temperature that is close to the injected fluid temperature. This is due to the high fluid velocity of injected fluid in the wellbore, and the upstream intervals have not been perforated (non-communicating intervals). Thus, the only heat transfer is heat conduction between the wellbore fluid and the surrounding reservoir. But the field DTS data show considerably irregular variations in temperature along the upstream stage intervals. These variations are caused by the completion effects. The non-uniform temperature profile is caused by different heat transfer behavior induced by completion hardware along the production casing string such as joints, clamps, and blast protectors, and by the sensing cable location in the cement, as well as the cement quality. Since the heat transfer behavior impacts the warm-back behavior as well as the temperature profile, the completion effects need to be considered in DTS interpretation.

A method of DTS interpretation considering the completion effects to diagnose multistage fracture treatments was developed. Since the heat transfer between a wellbore and a reservoir depends on the overall heat transfer coefficient describing heat conduction through the completion in a forward model, this parameter needs to be tuned along the entire wellbore. To calibrate the completion effect, the temperature inversion is conducted using the temperature measured at a stage interval that is upstream of a stage interval currently being treated. Since the interpreted stage interval is not perforated at that time, the thermal behavior at the non-communicating interval is governed by only the heat conduction through the completion environment. Once the effective values of the overall heat transfer coefficient are estimated along the interpreted stage interval, they can be assumed to be constant physical parameters. Then, the fluid volume distribution is interpreted by using the effective overall heat transfer coefficient profile along each interval.

The interpretation method developed in this study was demonstrated using field data, and it was concluded that the new DTS interpretation method provides more accurate diagnosis of fracture treatments.
Novel Completion Design to Bypass Damage and Increase Reservoir Contact: A Middle Magdalena, Central Colombian Case History
Authors: Polo Rosana , Arciniegas Jaime , Valencia Brian , Vulgamore Travis , Nuñez Walter , Ortega Camilo , Palisch Terry , Velez Eduardo , Tineo Roberto
Published: October 2020

The La Cira Infantas field is located in the Middle Magdalena basin in the Santander region of central Colombia. This oil-producing development is under secondary waterflood using five-spot and inverted seven-spot patterns. The reservoir has high vertical and horizontal heterogeneity, and there was concern about effectively draining the reservoir. A new hydraulic fracturing design was deployed for the first time in Colombia (and South America) to improve drainage and surveillance.

With over 1200 producers and 500 injectors, the La Cira Infantas waterflood is well established. Waterflood surveillance indicated less-than-optimal recovery due to near-wellbore skin in the injectors and suspected poor height coverage. A novel proppant technology was incorporated into the fracture design allowing for consolidation of the proppant pack in the fracture with low bottomhole temperature and minimal stress on proppant, enabling long-term undamaged injectivity. This technology also incorporates an inert tracer into the proppant grains, which provides propped height determination after the treatment using a neutron log. This multi-faceted proppant technology was successfully deployed on one well, and additional wells are planned in 2020.

This paper will first review the background of the field development including current completion techniques, along with the challenges being faced with the waterflood recovery. It will review the self-consolidating proppant technology and show the benefits of its use in this application to promote high-conductivity fractures and minimize damage to injectivity. The companion tracer technology will be presented along with plans to perform neutron logging and identify propped fracture height. This information can be fed into fracture propagation models to determine the fracture geometry, which is then used for reservoir and waterflood surveillance analysis. The technique allows for meeting the goal to improve injectivity into both high-skin and low-permeability reservoirs.

Although this proppant technology has been used in other frac pack applications, this is one of the first case histories of the technology being used on land for improving injectivity and waterflood coverage in Colombia. This paper will be useful for reservoir and completion engineers working on waterflood fields that contain vertically and horizontally heterogeneous formations, and wish to maintain undamaged injectivity, improve waterflood sweep efficiency, and monitor the proppant pack over time.
A New Horizon in Corrosion Prevention Using State of the Art High Power Laser Cladding Technology
Authors: Assiri Wisam , Asiri Ahmed , San Roman-Alerigi Damian , Batarseh Sameeh , Salman Muntadar
Published: October 2020

The objective of this work is to present a successful case study of deploying high power laser cladding in highly sour wells as protection from corrosion. High power laser cladding uses superalloy material and is welded to the pipe, creating a thin and strong film that adheres to the steel pipe. The technology is cost-effective and provides a long-term solution, extending the life of the pipes, casing, tubing, and other parts.

The method requires preconditioning the completion at the surface, applying a thin layer of superalloy (1 mm), and bonding it to the base material with a laser. The process will create a chemical bond between steel and the superalloy, which will result in a resistive layer facing the corrosive fluids. The technology was applied to carbon steel coupons (T-95 grade) and was cladded with three different superalloys Inconel-625, Inconel-825, and Hastelloy C-276. A bare coupon was used as a reference. The coupons were kept for three months downhole and later retrieved for analysis.

The technology was tested in extremely sour wells for three consecutive months. Well-A produces a high concentration of hydrogen sulfide (H2S) (35,000 ppm) while Well-B has a concentration of 14,000 ppm. A detailed analysis, including composition, X-ray fluorescence, environmental scanning electron microscope, and surface profiling on the coupons showed that the cladded samples have excellent resistance and no traces of corrosion on all the cladded coupons.

High power laser cladding is a cost-effective and promising technology that can extend the life of wells and minimize the frequency to replace the tubing due to corrosion issues. The cladded sample exhibits a more durable structure than the substrate materials. The superalloy thin layer protects from corrosion as it is a new pipe.
Using Markers for Production Logging in Horizontal Gas Wells with Multistage Hydraulic Fracturing
Authors: Katashov Alexander , Ovchinnikov Kirill , Belova Anna , Husein Nadir , Rivas Oscar , Buyanov Anton , Suprankov Kirill
Published: October 2020

The need for the use of modern technologies for diagnosing the work of the developed facilities and clarifying information on the productivity of the target formation arises when making decisions on the control of development, including designing and planning various kinds of technological measures, as well as conducting research to monitor the current state of existing wells. Traditional methods for monitoring the inflow profile are not always effective and cost-effective, especially when it comes to hard-to-recover reserves. One of the most progressive solutions is the use of marker studies based on the selection of markers from the produced fluid and their subsequent identification in samples taken at the wellhead [1]. The main advantage of this technology is that there is no need to suspend work for hoisting operations in order to obtain informative field-geophysical data during well operation. Moreover, the undoubted advantage of marker monitoring is its long-term nature since the technology allows continuous downhole data obtaining within several years. The subject of this work is a gas well with an extended horizontal wellbore, in which the 18-stage hydraulic fracturing using marked quartz polymer-coated sand was carried out.
A Petrophysical Method to Estimate Production Rate vs. Time Performance, and to Define Drainage Areas and Recovery Efficiencies
Authors: Holmes Michael , Holmes Antony , Holmes Dominic , Swartz Kent , Jones Brian , Aye Naing , Zimbrick Grant
Published: October 2020

Objective/Scope

The main objective is to build on prior publications of decline curve analysis, based on theoretical producing and fluid flow characteristics (Matthews and Lefkowits 1956, Fetkovitch 1975, Cox 1948).

In this paper, we relate petrophysical predictions of ultimate oil recovery to actual rate-time well performance by adjusting recovery efficiencies and well-bore drainage areas.

Method/Procedure/Scope

From an analysis of a number of producing wells in the Permian Basin a model (Zimbrick) has been derived for average decline curve performance. This model has been found to work in other basins; however, basin specific models are likely to be required in some situations.

This model is then combined with petrophysical estimates of recovery efficiencies to generate rate vs. time decline curves. This is then compared with actual production to determine drainage area. Three basic questions are then addressed:

Additional adjustments might then be necessary. Results can be interpreted as follows:

Results/Objectives/Conclusions

Results from the analyses of four oil wells in the Big Horn Basin of Wyoming are presented. All four wells have excellent log suites allowing for reliable petrophysical analysis, are now depleted, and have rate-time data available.

The nominal well spacing is for 15-acre drainage. Petrophysical predictions for rate-time performance were run for two basic cases:

Using a constant recovery efficiency of 20% the drainage areas were adjusted to get an exact match with actual performance.

For three of the four wells, adjusted drainage areas are significantly greater than 15 acres.

Factors influencing the calculated drainage areas are:

Novel/Additive Information

The method compares petrophysical estimates of recoverable hydrocarbons with actual rate-time performance, allowing for considerations of drainage areas and recovery efficiencies and the possibility of production coming from a fracture system and/or adjacent unperforated intervals.

Estimates can be made from the petrophysical analysis of adjacent undrilled locations of rate-time performance before the well is completed.
Dynamic Torque and Drag Model
Authors: Samuel Robello , Huang Wenjun
Published: October 2020

It is generally acceptable to use soft string model for simple wells and stiff string for high dogleg wells. But these models fail to reveal the complex mechanical behaviors of tubular string in tripping in, tripping out, and sliding drilling operations with time as some segments of tubular string may move upward and downward alternatively. As a result, the model under predicts or over predicts the behaviors of tubular string, and requires multiple calibrations of friction factor. To avoid this, a new model has been developed to estimate dynamic torque and drag. In the new model, the effects of tubular vibration, drill fluid, viscous force, and velocity-dependent friction force are all considered, which overcomes the shortcomings of all previous models. The new model can be used for calculating dynamic mechanical behaviors of tubular string under tripping in, tripping out, and sliding drilling operations. The results provide new insights that have not been previously presented and will provide valuable insights into well planning and designing.
Prediction of Zonal Flow Allocation Using Fiber-Optics Monitoring In a Complex Injector Well System
Authors: Satti Rajani , Bale Derek , Patel Amar , Nazarenko Pavel , Avella Oscar , Solorzano Pedro , Sanchez Walter , Giosa Carlos , Satizabal Monica , Vega Sandra , Hernandez Nini , Coronel Ivan
Published: October 2020

Injector well completions are typically carried out using two methods: simple and selective. The performance of injector wells has traditionally been evaluated using spinner-based injection logging tools (ILTs) or on-demand fiber optic distributed temperature and acoustic (DTS or DAS) sensing while logging the well performance every 3 months or once a year depending on the application. However, with such methods utilizing a snap shot approach, critical well performance information or possible anomalies are often missed due to measurements taken only during certain periods. Therefore, operators have explored the use of advanced fiber-optics methods such as permanent distributed temperature sensing (DTS) and permanent distributed acoustic sensing (DAS), that provide continuous, real-time measurements to enable understanding of dynamic well behavior at all times and mitigate any deferred or behavioral problems.

Of relevance to this work is a vertical, injector well in a competent sandstone formation of the Heavy Oil Chichimene field in Llanos Basin, Colombia. As a first step of the fiber-optics monitoring strategy, a careful evaluation of DTS and DAS based fiber-optics methods was conducted. Based on the data analysis and operational history, DAS-based fiber optics monitoring was chosen as the most effective monitoring solution for this well. Subsequently, a proprietary DAS algorithm was developed to analyze the data and estimate the flow allocation for all the four zones. The results include waterfall acoustic energy maps, temporal flow allocation profiles and most importantly, the zonal flow allocation values.

Predicted (DAS) zonal flow allocation data was compared with traditional injection logs (ILT) under different operational conditions (varied injection flow rates and valve choke settings). Based on comparable agreement between DAS and ILT data, the operator decided to replace ILT runs with DAS-based fiber optic monitoring, resulting in lower operational costs while enabling near real-time monitoring, and providing the continuous distributed data essential for the dynamic monitoring of the well. The successful application of fiber-optics monitoring to provide an injection profile in conjunction with a surface-controlled electric valve system demonstrates a significant potential to optimize the injection process in complex injector wells. Further, remotely controlling, monitoring and optimizing injection rates into the multi-segmented zones improves the service life of the injection operations, eliminates future intervention costs, and increases ultimate recovery.
Predict Reservoir Fluid Properties from Advanced Mud Gas Data
Authors: Yang Tao , Yerkinkyzy Gulnar , Uleberg Knut , Arief Ibnu Hafidz
Published: October 2020

In a recent paper, we published a machine learning method to quantitatively predict reservoir fluid gas oil ratio (GOR) from advanced mud gas (AMG) data. The significant increase of the model accuracy compared to traditional modeling approaches makes it possible to estimate reservoir fluid GOR based on AMG data while drilling, before the wireline operation. This approach has clear advantages due to early access, low cost, and a continuous reservoir fluid GOR for all reservoir zones. In this paper, we release further study results to predict other fluid properties besides GOR, which is essential for geo-operations, field development plans, and production optimization.

We use two approaches to predict other fluid properties. For the first approach, we develop machine learning models for reservoir fluid density, similar to the GOR prediction approach in the previous paper. Based on an extensive fluid database, we establish machine learning models to predict reservoir fluid density from C1 to C5 compositions (same format as AMG data). As the second approach, instead of developing a machine learning model for individual fluid property from C1 to C5 compositions, we investigate the most important properties for EOS fluid characterization: C6 and C7+ compositions, and molecular weight and density of C7+ fraction. Once these properties are in place, the entire spectrum of fluid properties can be calculated with the equation of state (EOS) model.

The results of fluid property prediction are satisfactory with both approaches. The reservoir oil density prediction has a mean average error (MAE) of 0.039 g/cm3. The accuracy is superior to typical density derived from the pressure gradient from wireline logging data. For the essential fluid properties required for EOS model prediction, the overall accuracy is acceptable compared with laboratory measurements. The reservoir fluid properties predicted from the EOS model are similar or better than the predictions from individual machine learning models. We applied the field measured AMG data into the fluid property models and achieved reasonable results, as illustrated by the reservoir fluid density example.

The paper completed the methodology to predict all fluid properties based on AMG data. This work paves the way to generate a complete reservoir fluid log for all relevant fluid properties. The method has a significant business impact due to the full coverage of reservoir fluid properties along the well path compared with the availability of discrete PVT samples. The advantage of providing fluid properties in all reservoir zones along the well path far outweighs the limitation of somewhat reduced fluid property accuracy.
The Effect Particle Size Distribution of Granular LCM on Fracture Sealing Capability
Authors: Lee Lu , Dahi Taleghani Arash
Published: October 2020

Lost-Circulation Materials (LCMs) are used to control and mitigate fluid loss problems by fracture sealing. Without a proper lost-circulation technique, an increase in non-productive time (NPT) and well control problems may occur. A good design in the LCMs to seal fractures and to successfully prevent the occurrence of a serious lost-circulation event can alleviate a heavy drilling budget. Various LCMs exist in the market, of which can be broadly categorized as fibrous, flaky, or granular. Granular LCMs are effective in sealing fractures and are of low cost. A successful bridging and sealing from the LCMs depend on their mechanical strengths, shapes, sizes, and particularly, the particle size distribution (PSD). In this paper, the computational fluid dynamics (CFD) and the discrete element method (DEM) are coupled to simulate the sealing capabilities of granular LCMs on different PSDs. A single smoothed fracture is created for the study of such phenomenon. The dynamic process of fracture sealing involves the initiation of bridging from large particles and the effective particle packing to form a seal, thereby reducing the fluid loss. It is found that the LCMs with bimodally distributed sizes can achieve effective fracture sealing. The coarse LCMs should be close to the average fracture size, where accurate measurement is required. The median of the fine to coarse LCM sizes should not exceed 0.67 for fracture sealing to occur. The LCM blend consists of coarse and fine LCMs, where the fine to coarse LCMs by volume is around one third.
Effectiveness of a Smart Hydrogel in Well Leakage Remediation
Authors: Welch Nathan , Gilbertson Robert , Boukhalfa Hakim , Roback Robert , Carey J. William , Goodman Harvey , Rösli Ursula , Gisiger Jocelyn , Espie Tony , Minnig Christian
Published: October 2020

Leakage in carbon storage and hydrocarbon wells continues to be an area of concern in the development and abandonment of reservoirs. Industry need for a leakage remediation sealant that can perform in systems beyond the capability of cement squeezes has driven the development of a CO2/pH activated "smart" gel. Exploratory laboratory tests and a mock field scale well test were performed to determine the effectiveness of the smart gel. Control of the smart gel particle size distribution was demonstrated through batch synthesis experiments. Microfluidic experiments show some of the mechanisms leading to the successful sealing of an engineered fracture system. Initial and subsequent testing of the deployed smart gel in a leaky mock well completion proves the effective scale up of the smart gel sealing capability and can further drive wider adoption of this unique technology.
Laboratory Visualization of Enhanced Gas Recovery in Shale
Authors: Elkady Youssef , Kovscek Anthony
Published: October 2020

In this work, we lay the experimental groundwork for measuring CO2 storage, and other industry-relevant gases, in shale on a core scale. This works emphasizes the role of adsorption on gas storage using two core samples (one Eagle Ford and one Wolfcamp). Mass balance and Computed Tomography (CT) methods are used independently to co-validate our results. The validation process allows for confidence in the accuracy of the CT visualizations. In addition, the CT method significantly reduces the characterization time needed for measuring gas storage before running any further investigations related to gas flow and recovery.

The pulse-decay technique is initially used to quantify apparent porosity, permeability, and adsorption for He, N2, Kr, CH4, and CO2 at room temperature (and 42 °C in some cases) up to 800 psia pore pressure. In the case of Kr, Eagle Ford core (EF1) is imaged at the end of each pressure pulse step to compare CT-derived to pulse decay derived results. At 650 psia, CO2 and Kr storativity (SCF of gas per ton of rock) in sample EF1 have roughly 4.5× and 2× the storativity of He, respectively. Absolute adsorption of CO2 (181 SCF/Ton) is significantly greater than N2 (5 SCF/Ton) and Kr (45 SCF/Ton) at 650 psia pore pressure. Furthermore, our proposed CT approach yields a good match to the mass balance characterization results for Kr as opposed to the conventional CT formulation.

Permeability results show negative correlation between adsorption affinity of gas and sample liquid-like permeability. In the case of Kr and N2 measurements on sample EF1, the greater compressibility of Kr is overcome by its larger adsorption affinity resulting in a greater than N2 permeability at lower pore pressures but lower permeability at higher pore pressures. The Wolfcamp sample (WC2) captures a potentially irreversible effect of CO2 on permeability attributed to either permanent matrix swelling or matrix softening.

This study bridges both CT and mass balance derived results to ensure accurate visualization of the physics during characterization. Both methods show a better displacement of in-situ Kr (proxy for CH4) with CO2 as compared to N2 injection. CT visualizations of both gas displacement experiments show two relatively permeable flow pathways emerge during early times.
Reservoir Implications of Measured Thermodynamic Equilibrium of Crude Oil Components: Gases, Liquids, the Solid Asphaltenes, and Biomarkers
Authors: Mullins Oliver C. , Johansen Yngve Bolstad , Achourov Vladislav , Chen Qing , Cañas Jesus Albert , Chen Li , Pomerantz Andrew E. , Forsythe Julia C. , Betancourt Soraya S. , Bayestehparvin Bita
Published: October 2020

The process of compositional equilibration of reservoir crude oil requires excellent reservoir connectivity. For example, the measured of asphaltene gradients for indications of connectivity is now commonplace. In addition, equilibrated fluids imply various other important fluid and reservoir properties. However, some measurements of distinguishing equilibration from disequilibrium have been ambiguous. Here, we provide measurement protocols which provide robust determination of equilibrium within a framework of reservoir fluid geodynamics. Thermodynamic modeling of measured asphaltene gradients vertically and laterally with considerations of solution gas provides a robust determination of equilibrium. In addition, two-dimensional gas chromatography with its high-resolution compositional evaluation especially within a geochemical context can corroborate conclusions from asphaltene gradient analysis. Outlier locations in the reservoir can often be found and aid considerably in delineating the important reservoir fluid geodynamic processes operative in the reservoir and validating the assessments regarding equilibrium. The evolution of lateral equilibration is shown in a reservoir with known initial (at time of charge) and present-day lateral gradients. Modeling clarifies the convection which has occurred over geologic time to minimize these lateral gradients. Different processes of mass transport in reservoirs are compared. Equilibration processes and corresponding asphaltene gradient measurements are analyzed for differing geologic times including a very young (Pleistocene and Pliocene) and very old (Cretaceous) reservoir charges in different reservoirs. The important role of convection is shown, with its critical requirement of a density inversion.
Using Production Data to Constrain Resource Volumes and Recovery Efficiency in the Marcellus Play of West Virginia
Authors: Boswell Ray , Carney B. J. , Pool Susan
Published: October 2020

Recovery efficiency (RE) is a poorly constrained parameter with respect to unconventional resource development. However, the increasing volume and quality of data related to Marcellus development in West Virginia provide an opportunity to assess this parameter. In this report, we develop a map of estimated ultimate recovery (EUR) per square mile (mi2) for the Marcellus Play in West Virginia and compare that map to published estimates of both technically recoverable resources (TRR) and original gas-in-place resources (GIP). These comparisons reveal that Marcellus wells appear capable of producing significantly more gas than previously estimated and, throughout large areas of the State, more gas than has been assessed to be in place. While explanations for this observation likely include both potential overestimation of EUR and underestimation of GIP, our review indicates that a primary source of the discrepancy is overly-conservative GIP calculations. New GIP calculations have been conducted for a range of wells that appear to account for the bulk of the "excess gas" by including GIP volumes from bounding formations determined likely to be part of the larger Marcellus Reservoir Unit (MRU). In northeastern West Virginia, the MRU includes both the Marcellus Formation and the lower 300 ft of the Mahantango Formation. In northwestern West Virginia, units up to the Cashaqua Shale Member of the Sonyea Formation are included in the MRU. These new GIP/mi2 values, when compared with our estimates of TRR/mi2, indicate that ultimate RE for ongoing development generally ranges between 20 to 60%.

Our approach to estimate TRR/mi2 is based on identification of 166 Marcellus "development sites" in northern West Virginia. Each development site was selected to consist of multiple horizontal wells that were drilled as a coordinated activity at a common spacing over a short period of time by a single operator. Sites and wells also were selected to maximize both the relevance (post 2012 vintage wells where possible) and reliability (more than 18 months production history) of the EUR forecasts. Site area was determined as the product of cumulative lateral length and well spacing. The cumulative EURs for all wells in each site were estimated (using two independent sources for EUR estimation) and those sums were divided by the area to obtain a single point estimate of TRR/mi2. Our review indicates that Marcellus Play resource assessments tend to be overly conservative. This analysis shows the value of focusing on the most relevant production data and using those data as a ground truth check on resource assessments.
A Numerically Optimized WAG Injection Strategy for Successful Implementation of Foam Assisted Gas EOR
Authors: Katiyar Amit , Nguyen Quoc
Published: October 2020

The objective of this paper is to numerically determine necessary constraints of a novel water-alternating-gas (WAG) foam injection strategy for conformance correction and improved oil recovery with gas-EOR applied in conventional reservoirs.

A 3D 5-spot reservoir simulation model is created that simplistically captures a severe vertical conformance problem in a CO2 WAG flood. This simulation model is run on a conservative WAG strategy to lead the model to a mature gas flood state. An empirical foam model is used to implement the foam assisted gas EOR in this simulation model and determine the necessary injection constraints for its successful production-enhancing field deployment.

The simulation results of the gaseous-foam EOR technology applied in 5-spot model show that the constant rate foam injection is ideal for conformance correction and improved oil recovery even if the baseline WAG operation is maintained. Typically, most of the current WAG fields operate at constant surface pressure. The simulation results show that with constant surface pressure and baseline WAG operation, foam generation results in loss of injected gas rate and volume and potentially limits the oil recovery even with improved conformance. To mitigate this productivity gap, foam WAG strategies with higher gas water ratios (GWR) were investigated. It is first confirmed that in a pattern with conformance issues, higher GWR makes the typical gas floods even worse. However with constant surface pressure foam injection, higher GWR allows ideal gas-water mixing ratios for stronger foam generation without impacting the target injection gas volume and reservoir pressure. In addition, during foam injection, higher injection pressure than baseline can further allow maintaining baseline gas injection rates and volumes that results in improved oil recovery with more uniform gas sweep.

Prior field tests of gaseous foam conformance solution have, at times, shown inconclusive results. This study is critical to identify the limitations of the gaseous foam-EOR technology applied under constant surface pressure constraints and to provide potential solutions through optimized GWR and/or injection pressure.
Improving ESP Run Lives on Aggressively Declining Wells: A Case Study in the Permian Basin
Authors: Escobar Katherine , Gibson Matthew , Watson Arthur , Duran Salvador , Andara Oswaldo
Published: October 2020

The current strategy for many operators of US land has moved to increase production during the early stages of new wells to maximize immediate cash flows and rate of return. Electric submersible pumps (ESPs) have long been an accepted and widely used artificial lift method capable of moving high volumes of fluid with relatively moderate efficiencies and run lives. Nevertheless, in some plays in the Permian Basin, the technical requirements for artificial lift systems has increased, especially for ESPs. For the specific case of this study based on almost 40 wells in the Spraberry field, rapidly declining flow rates starting around 5,000 bbl/d and declining to 2,000 bbl/d or less in only two to four months, have inevitably forced the current pump stages to work significantly outside of their recommended operating range (ROR).

Even though compression pumps were designed to extend operation outside of their ROR and onto the left side of the curve, the aggressive decline rates seen in this case study have shown how excessive downthrust can still be a concern on compression construction pumps. This paper comprises a case study of pulled equipment that was operating significantly below the ROR. This operating condition led to severe net down thrust force, axially deflecting the components downward.

After the production challenges were analyzed and the pulled ESPs showed evidence of excessive downthrust, a new pump stage and ESP design were proposed to increase the flexibility of the ROR and adapt to the rapidly declining flow rates. This new technology was initially developed for the Bakken, and due to its proven flexibility, its use has been extended to more unconventional and conventional plays across the US. Even when the production declines and the pump's operating point moves to the flat section of the head-rate curve, the data on this study has shown that the features of the new stage such as hydraulic improvements, increased axial stiffness and additional travel, have led to enhancements in downthrust management. Ultimately, this translated into 31% run life improvement for the operator. Finally, due to the improvements on the design with a reduced number of stages, power consumption has decreased and impacted the cost of barrel produced.
An End-to-End Deep Sequential Surrogate Model for High Performance Reservoir Modeling: Enabling New Workflows
Authors: Navratil Jiri , De Paola Giorgio , Kollias Georgos , Nadukandi Prashanth , Codas Andres , Ibanez-Llano Cristina
Published: October 2020

Despite considerable progress in the development of rapid evaluation methods for physics-based reservoir model simulators there still exists a significant gap in acceleration and accuracy needed to enable complex optimization methods, including Monte Carlo and Reinforcement Learning. The latter techniques bear a great potential to improve existing workflows and create new ones for a variety of applications, including field development planning. Building on latest developments in modern deep learning technology, this paper describes an end-to-end deep surrogate model capable of modeling field and individual-well production rates given arbitrary sequences of actions (schedules) including varying well lo-cations, controls and completions. We focus on generalization properties of the surrogate model which is trained given a certain number of simulations. We study its spatial and time interpolation and extrapolation properties using the SPE9 case, followed by a validation on a large-scale real field. Our results indicate that the surrogate model achieves acceleration rates of about 15000x and 40000x for the SPE9 and the real field, respectively, incurring relative error ranging between 2% and 4% in the interpolation case, and between 5% and 12% in the various spacial and time extrapolation cases. These results provide concrete measures of the efficacy of the deep surrogate model as an enabling technology for the development of optimization techniques previously out of reach due to computational complexity.
A Comprehensive Rheological Characterization of HPAM-Based Polymers for the Potential EOR Implementation
Authors: Karimov Damir
Published: October 2020

Polymer flooding is well-established and effective independent technique for improving oil recovery. However, this method is not considered viable due to the limitations such as retention at the unfavorable conditions, weak stability in the presence of divalent ions, high cost and its inability to work under high temperature-high salinity conditions. For that reason, this paper will evaluate the proper conditions and criteria for the successful implementation of polymer flooding.

Four different partially hydrolyzed polyacrylamide (HPAM) based polymers were prepared using standard API procedure for polymer preparation. The effect of concentration and temperature and concentration was evaluated through different rheological measurements. The experimental studies on evaluating the performance and stability of polymers were investigated by performing long-term thermal stability and mechanical degradation tests. Thus, comprehensive rheological studies with partially hydrolyzed polyacrylamide (HPAM) based polymer solutions were designed for defining suitable polymer solution.

The preliminary experimental work was carried out at 25-80 °C temperature range and at different concentrations (1000-3000ppm). All four HPAM based polymer solutions showed a typical non-Newtonian rheological characteristic with shear thinning behavior. The obtained results also showed the dependence of the polymer viscosity on the concentration and temperature. As a result, Flopaam 5115 retained and showed the maximum viscosity comparing to other polymer solutions under these conditions. Then, the performance and stability of polymers was tested through different sets of rheological experiments such as long-term thermal stability and mechanical stability tests. In this case, Flopaam 5115 also showed good thermal and mechanical resistance at 80 °C for more than one hundred days and at 23900rpm, respectively.

Through the series of different rheological experiments, we identified the most suitable polymer and the conditions that would not disturb the performance and effectiveness of the particular solution. A comprehensive study on the screening different HPAM solutions showed promising results for a future investigation in this direction. The research based on different screening parameters such as concentration, temperature, time, and mechanical exposure was found to be vital for the successful implementation of polymer flooding on a field.
Efficacy of sugammadex in the prevention of postoperative residual curarisation and related complications in patients over 65 years of age undergoing general anaesthesia.
Authors: Pietraszewski Piotr , Gaszynski Tomasz
Published: October 2020

Background.
Neuromuscular blocking drugs have contributed to advances in anaesthesiology. The first agent blocking neuromuscular transmission was curare. Alarming respiratory complications in patients recovering from anaesthesia were reported from the very beginning of curare use. The currently used non-depolarizing muscle relaxants are regarded as safe. However, postoperative residual curarisation may be associated with the risk of complications in the first few days after general anaesthesia, especially in patients older than 65 years. This study aims to investigate the effect of sugammadex on the incidence of postoperative residual curarisation, postoperative critical respiratory events, and postoperative cognitive dysfunction. Although recommended, neuromuscular monitoring is still not standard practice during general anaesthesia with the use of muscle relaxants.
Methods.
Overall, 351 patients aged 65-91 years were included in the observational study. Patients were anaesthetised at the M. Kopernik Provincial Multispeciality Centre of Oncology and Traumatology in Lodz. Spirometry and MMSE (Mini-Mental State Examination) were performed in patients one day before the surgery and one day postoperatively. Neuromuscular blockade was not monitored intraoperatively. One measurement was taken during recovery from anaesthesia. Anaesthetists made a decision to administer either a dose of 2mg/kg sugammadex (group S) or 0.05 mg/kg of neostigmine iv (group N) during recovery from anaesthesia.
Results.
There were significant differences (p<0.001) between the groups in postoperative TOF ratios. The percentage of patients with TOF ratios >0.9 was significantly higher in the S group than in the N group (83% vs 49%). The incidence of critical respiratory events was significantly lower in the S group compared to the N group (7.6% vs 17%). The study demonstrated significant differences in the postoperative scores of MMSE.
Conclusions.
Sugammadex effectively prevents postoperative residual curarisation in patients over the age of 65. It reduces the incidence of critical respiratory events in elderly patients. The study revealed a slight trend that full reversal of the neuromuscular blockade may correspond with the improvement of postoperative cognitive functions.
Trial registration: Trial ID: ISRCTN17481425 Date registered: 27/01/2020, Link: https://www.isrctn.com/ISRCTN17481425
The Quality of Life after Laparoscopic Pyeloplasty due to Ureteropelvic Junction Obstruction: Assessment After Long Term Observation.
Authors: Panek Wojciech , Janczak Dawid , Panek Marta , Szydełko Urszula , Chrzan Rafał , Chabowski Mariusz , Szydełko Tomasz
Published: October 2020

Background: A change in the assessment of treatment effectiveness is currently observed. More and more emphasis is being placed on assessing the impact of treatment on patients’ quality of life (QoL). Data on postoperative quality of life in patients undergoing pyeloplasty is scarce. The aim of the study was to assess the quality of life of patients who had undergone laparoscopic pyeloplasty due to ureteropelvic junction obstruction.Methods: The study group consisted of 95 patients who had consecutively undergone laparoscopic pyeloplasty due to ureteropelvic junction obstruction in a single center, between 2002 and 2009, from whom 26 consented to participate in a study. We evaluated their quality of life using WHOQOL-BREF questionnaire and an additional form, created by one of the authors, prepared to assess specifically health related quality of life after pyeloplasty. In all the patients, postoperative, functional outcome was assessed using diuretic renography. Results: Mean follow-up time was 89.8 months. Overall, 96% of study patients were satisfied with the procedure and all of them would consent to another pyeloplasty if needed. Dissatisfaction of one patient was caused by an insufficient decrease in pain level. All the patients reported that the postoperative pain intensity did not significantly affect their life and professional activity. Conclusions: Laparoscopic pyeloplasty is associated with excellent functional outcomes and - most of all - the majority of patients are satisfied with the treatment results. There seems to be no correlation between functional outcome and postoperative satisfaction.
The effect of Epstein-Barr virus infection in central nervous system on prognosis of patients with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis
Authors: Jin Zhili , Wang Yini , Wu Lin , Wang Zhao
Published: October 2020

Background

This study was conducted to investigate the effect of Epstein–Barr virus (EBV) infection in the central nervous system(CNS) on the prognosis of Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH) patients.
Methods

Clinical information of 88 EBV-HLH patients diagnosed and treated in our medical center from January 1, 2017 to September 1, 2019 was included.
Results

The 88 patients were divided into 2 groups based on whether the result of their CSF EBV-DNA testing was positive. Statistical difference in survival time was found between the EBV + group and EBV- group(44 vs. 44 ; P = 0.049). The 88 patients were separated into 2 groups according to whether underwent allogenic hematopoietic stem cell transplantation (allo-HSCT). There were statistically differences in the allo-HSCT group and non allo-HSCT group (60 vs. 28 ;P = 0.040). Among the 60 EBV-HLH patients who did undergo allo-HSCT, they were divided into 2 groups in the light of whether the result of CSF EBV-DNA testing was positive. Statistical difference in survival time was not found between the EBV + group and EBV - group( 32 vs. 28; P = 0.540). Among the 28 EBV-HLH patients who did not undergo allo-HSCT, they were divided into 2 groups based on whether the result of CSF EBV-DNA testing was positive. Significant statistical difference in survival time was found between the EBV + group and EBV - group(12 vs. 16; P = 0.002). The 44 EBV-HLH patients who were EBV-DNA-positive in their CSF were separated into 2 groups for survival time analysis according to the highest copy number of EBV-DNA in the CSF, using 1.0E + 04 copies/ml as the cutoff, and statistical difference in survival time was found between the two groups(P = 0.030).
Conclusions

EBV infection of the CNS was found to be a poor prognostic factor in EBV-HLH patients. The changes in EBV-DNA in CSF and the EBV-DNA copy number were found to affect the prognosis of EBV-HLH patients. Monitoring the changes in EBV-DNA copy number in the CSF was of great significance. Allo-HSCT improved the prognosis of EBV-HLH patients, including patients who tested positive for EBV-DNA in the CSF.
A Network Pharmacology Approach to Understanding the Mechanisms of Action of Traditional Medicine: Rheum L. for Diabetic Kidney Disease
Authors: Luo Jinli , Piao Chunli , Jin De , Wang Li , Zhao Xiaohua , Lian Fengmei , Tong Xiaolin
Published: October 2020

BackgroundRheum L. (Da-huang in pinyin, Radix Rhei Et Rhizome in pharmaceutical name), a classic Chinese herb, has been extensively used to treat diabetic kidney disease in clinical practice in China for many years. However, the pharmacological mechanisms of Rheum L. remain elusive. To decrypt the underlying mechanisms of Rheum L. in the treatment of diabetic kidney disease using a systems pharmacology approach. MethodsA network pharmacology-based strategy was proposed to elucidate the underlying multi-component, multi-target, and multi-pathway mode of action of Rheum L. against diabetic kidney disease. We collected putative targets of Rheum L. and a network of the interactions among the putative targets of Rheum L. and known therapeutic targets of diabetic kidney disease was built. The major hubs were imported to the Database to perform a pathway enrichment analysis. ResultsA total of 6 active ingredients and 271 targets of Rheum L. were picked out. 11 cellular biological processes and 18 pathways of Rheum L. mostly associated with inflammatory response, apoptosis, fibrosis, and peripheral circulation. ConclusionsRheum L. could alleviate diabetic kidney disease via the molecular mechanisms predicted by network pharmacology.
The Protective Effect of Aesculin Eye Drops on Dry Eye Syndrome Mice
Authors: Liu Xinquan , Su Jing , Fang Yue , Wang Dahu , Jiang Dan , Dong Zhiguo
Published: October 2020

Background: The objective of this study was to test the effectiveness of the novel aesculin (AES) eye drops on treating dry eye syndrome (DES), using murine model. Methods: Dry eye was induced in murine eye with the use of an intelligent controlled environmental system (ICES). High-flow air which had been desiccated within the ICES, induced the DES. Treatment included Aesculin eye drops for 14 days. After expiration, corneal fluorescein staining was examined and stained with an endothelial maker created for tracking of lymph: Lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). Subsequently, real-time PCR and ELISA were completed to quantify secretion of TNF-α，IFN-γ，IL-1β and IL-8 in serum, ocular surface and lacrimal gland. Results: Aesculin eye drops significantly repaired ICES-induced corneal injury in murine models Statistically significant increase in lymph angiogenesis was observed at day 14 of observation. Consequently, DES in treatment group was reduced using aesculin eye drops. aesculin eye drops can significantly inhibit lymphangiogenesis and reduce inflammatory cytokines levels in mice. The percentage of Th1 and Th17 cells were decreased after treating with aesculin eye drops, while the percentage of Treg was increased. Injection of VEGF-C into mice can reduce the efficacy of aesculin eye drops in ICES-induced DES. Conclusion: as treatment group of murine models indicated significant reduction of inflammation in the cornea associated with DES, treatment of DES with aesculin eye drops, should be considered a viable treatment method for DES.