bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stimulation of Wells Damaged by Barite Present in Filter Cake or Scale
Authors: Ivanishin Igor , Nasr-El-Din Hisham A. , Solnyshkin Dmitriy , Klyubin Artem 
Published: February 2021

SummaryHigh-temperature (HT) deep carbonate reservoirs are typically drilled using barite (BaSO4) as a weighting material. Primary production in these tight reservoirs comes from the network of natural fractures, which are damaged by the invasion of mud filtrate during drilling operations. For this study, weighting material and drilling fluid were sampled at the same drillsite. X-ray diffraction (XRD) and X-ray fluorescence analyses confirmed the complex composition of the weighting material: 43.2 ± 3.8 wt% of BaSO4 and 47.8 ± 3.3 wt% of calcite (CaCO3); quartz and illite comprised the rest. The drilling fluid was used to form the filter cake in a high-pressure/high-temperature (HP/HT) filter-press apparatus at a temperature of 300°F and differential pressure of 500 psig. Compared with the weighting material, the filter cake contained less CaCO3, but more nondissolvable minerals, including quartz, illite, and kaolinite. This difference in mineral composition makes the filter cake more difficult to remove. Dissolution of laboratory-grade BaSO4, the field sample of the weighting material, and drilling-fluid filter cake were studied at 300°F and 1,000 to 1,050 psig using an autoclave equipped with a magnetic stirrer drive. Two independent techniques were used to investigate the dissolution process: analysis of the withdrawn-fluid samples using inductively coupled plasma-optical emission spectroscopy, and XRD analysis of the solid material left after the tests. The dissolution efficiency of commercial K5-diethylenetriaminepentaacetic acid (DTPA), two K4-ethylenediaminetetraacetic acid (EDTA), Na4-EDTA solutions, and two “barite dissolvers” of unknown composition was compared. K5-DTPA and K4-EDTA have similar efficiency in dissolving BaSO4 as a laboratory-grade chemical and a component of the calcite-containing weighting material. No pronounced dissolution-selectivity effect (i.e., preferential dissolution of CaCO3) was noted during the 6-hour dissolution tests with both solutions. Reported for the first time is the precipitation of barium carbonate (BaCO3) when a mixture of BaSO4 and CaCO3 is dissolved in DTPA or EDTA solutions. BaCO3 composes up to 30 wt% of the solid phase at the end of the 6-hour reaction, and can be dissolved during the field operations by 5 wt% hydrochloric acid. Being cheaper, K4-EDTA is the preferable stimulation fluid. Dilution of this chelate increases its dissolution efficiency. Compared with commonly recommended solutions of 0.5 to 0.6 M, a more dilute solution is suggested here for field application. The polymer breaker and K4-EDTA solution are incompatible; therefore, the damage should be removed in two stages if the polymer breaker is used.
A New Tool-less Layered Fracturing Technology and Its Pilot Application in Deep Thick Formations
Authors: Wang Daobing , Zhou Fujian , Ge Hongkui , Liu Xiongfei , Zlotnik Sergio , Shi Yang , Yang Xiangtong , Yuan Xuefang , Li Xiuhui , Tan Yanxin , Luan Tingting 
Published: February 2021

ABSTRACT
Multi-layer fracturing technology is challenging because of the risk of packer failure and high cost in the deep thick formation. It depends largely on the effectiveness of packer tools. However, a new degradable fiber ball could be successfully used to temporarily block the open perforations, and then the layer with higher fracturing pressure is broken down. This paper presents a new tool-less layered fracturing technique and its pilot test results with this special material.
A series of laboratory experiments were conducted to evaluate the feasibility of this new technique. Degradable fiber balls were applied to perforated pipes under simulated reservoir conditions. The ball carried by the fluid first sealed the perforation holes and then increased the pressure in the pipe to simulate the resistance to pressure. In addition, the fluid was heated up to 140°C to simulate the degradation rate of fiber balls. Throughout these processes, the flow rate, temperature and pressure were continuously monitored for subsequent analysis.
Experimental and application results showed that: (1) fiber balls could be thoroughly degraded at 140°C temperature after six hours; (2) at a pressure difference of 50-70MPa, its deformation rate was less than 1.5%, which indicated its higher compression capability; (3) it could effectively block the perforation holes at 90°C and a pressure difference of 20MPa; (4) The blockage of perforations by the fiber ball could significantly enlarge the net pressure in the wellbore. This technique was applied for 35 wells in a deep and thick oil reservoir, which had achieved a great success and the post-treatment oil production was enhanced by 50-60% compared with conventional stimulation techniques.
Validation and Analysis of Past PVT Studies from a Complex and Mature Offshore Asset in Trinidad
Authors: Bagoo D.E. , Ramnarine M.L. , Rodriguez C. J. , Hernandez M. 
Published: February 2021

Abstract
In 2005, NGC, Petrotrin and Repsol E&P T&T Ltd. as joint venture partners, acquired the TSP asset with Repsol as the operator. The three fields, Teak, Samaan and Poui, have been in production for over 40 years and are highly complex, extremely compartmentalized and consist of over 10 different sands and reservoirs. Over 100 PVT files for the three fields are available; most of which were done in the 1970's by different labs using different protocols and procedures. All files were handed over in paper form which needed digitization as well as validation.
Valid PVT data provides vital information for the characterization of reservoir fluids. The establishment of fluids' physical and PVT properties help determine in situ and stock tank volumes, strategies for production, flow assurance issues for facilities design and provides guidelines for effective and efficient reservoir management throughout the life of the asset.
Numerous techniques exist for assessing and evaluating the quality of PVT data. This paper will describe the best practices used to validate TSP PVT data, such as the material balance tests and the Y-function linearity tests as well as the applications of the validated data through examples and case studies. Some of which include the development of trends which can be extrapolated for use in new prospects, infill and developmental drilling. Additional benefits include the recognition of flow assurance issues such as wax and sulphur compounds and the sampling and design of relevant PVT experiments for new wells. Production history combined with valid PVT data provides a powerful tool to help in the prediction of expected fluid types and fluid behaviour as pressure changes in planned new wells. It also provides additional technical support for which improvements to the fluid sampling program can be made to acquire the most representative fluid samples from the reservoir.
Evaluating the Effects of CO2 Injection in Faulted Oil Reservoirs
Authors: Augustus A. , Alexander D. 
Published: February 2021

Abstract
The geologic sequestration of carbon dioxide (GCS) into depleted reservoirs has been contemplated and tested in several projects globally both for permanent storage of carbon dioxide (CO2) and enhancing oil recovery (EOR). Utilization of geologic sequestration as a mitigation strategy to reduce the effects of anthropogenic CO2 into the atmosphere may be costly without proper incentives. This cost can be lowered when incremental oil is recovered in mature fields because of rising oil prices and possibly earning carbon credits for sequestered CO2. The injection of CO2, for most of the infrastructure should be in place for mature fields. Therefore many EOR coupled with CO2 sequestration projects attempt to maximize the recovery of oil whilst storing as much CO2 as possible.
Many oil reservoirs are reaching or have reached their maturity therefore secondary and tertiary methods for EOR have become increasingly important for sustainable volumes of oil to be produced. Reservoir simulators have become increasingly important in the pre-evaluation of these projects for proper reservoir management and evaluation. One of the most critical problems when considering the geologic storage of CO2 is the risk of leakage which can lead to seepage from the storage area. In Trinidad and Tobago (T&T) many reservoirs are highly faulted. Some faults form an integral part of the structural traps whilst others are leaky and provide migration pathways for the injected CO2 to return to surface.
A simulation study was conducted using the commercial compositional simulator CMG-GEM. The model described in this paper seeks to optimize the injection of CO2 into an oil reservoir with some degree of compartmentalization due to faulting whilst maximizing the amount of incremental oil that can be produced. One of the main considerations will be to maximize the sweep efficiency below the fracture pressure and fault entry pressure. The model is intended for a type of formation likely to be used for storage in Trinidad. We conducted sensitivity analysis on the injection rate and fault transmissibity in an analogous field to those located offshore Trinidad.
It was concluded that faults transmissibility affect the overall production of oil reservoirs. Sealing faults stored less CO2 and had less cumulative production than non sealing faults.
A Model for Extending the Heptanes plus Fraction for Trinidad Gas Condensates
Authors: Mayrhoo R. , Hosein R. 
Published: February 2021

Abstract
An accurate description of pseudo-component compositions is required for Equation of State predictions for gas condensate systems. Very often these extended experimental data are unavailable and must be generated using mathematical models, of which the exponential and the three-parameter gamma distribution functions are the two most widely used. The development of these two techniques was based on the assumption of a continuous molar relationship for pseudo-components. However, experimental compositional data for gas condensate systems show discontinuities in this relationship at SCN8 and SCN13.
The above models when applied to extend the C7+ fraction for Trinidad gas condensates, under predict the SCN8 mole percent and over predict the SCN12 mole percent due to the aforementioned discontinuities. The Average Absolute Deviation between the predicted and experimental SCN8 and SCN12 data were both greater than 25 percent. The two coefficient method described by Ahmed et al., when applied to extend the C7+ fraction, reduced the discontinuity at SCN8 to less than 12 percent. However the SCN12 group still had a deviation greater than 18 percent. These results show that existing models were not designed to take care of these discontinuities and should be used with caution when extending experimental data beyond SCN7.
The Model described in this study resolves these discontinuities in the molar relationships at both SCN8 and SCN12 with an Average Absolute Deviation between the predicted and experimental compositions of less than 10 percent. This model can quite easily be included in Equation of State packages for a more accurate description of compositions for Trinidad gas condensates for performing compositional simulation studies. A partial analysis beyond the C7+ fraction is not required with this new model.
A Methodology for Screening and Ranking of Reservoirs for Light Oil Air Injection Implementation
Authors: Niz-Velasquez E. , Trujillo M. L. , Delgadillo C. , Padilla J. 
Published: February 2021

Abstract
A great portion of the produced oil currently comes from mature fields, reason why the increase in oil production of current reservoirs is the main objective of oil companies.
Thermal enhanced oil recovery processes have been studied, implemented and improved over the years. In the last decade there has been significant interest in the light oil air injection (LOAI) process since the successful implementation of the process known as High Pressure Air Injection in the Buffalo Field (USA), which is a variation from the air injection process in light oil, applicable to deep reservoirs with low permeability and porosity. Proof of this are the West Hackberry Field (USA), more than five commercial projects along the Willinston Basin (USA) and recently a pilot in the Zhong Yuan Field (China). Additionally, feasibility studies have also been initiated and performed in Mexico, Argentina and Colombia.
This article proposes screening criteria for the selection of potential light oil reservoirs to be candidates for air injection, as well as a general methodology for the prioritization of the reservoirs with the highest LOAI implementation potential. Said methodology employs screening criteria, analogies and numerical simulation. The first part goes beyond the binary screening by assigning a weight to each one of the criteria, therefore resulting in a numerical ranking. For the analogies the reservoirs in which the technology has already been applied are grouped in four group types, against which the field on evaluation is compared. There is also a numerical simulation in 1D – 2D, where the injectivity with or without pressurization is evaluated, as well as the displacement stability. Additionally a multi-criteria evaluation method is used to select the best candidate.
Dynamic Permeability Model of Coal Seam and Analysis of Various Influence Factors
Authors: Wang Y. , Xu J. , He W. , Jiang R. , Wang S. , Li S. 
Published: February 2021

Abstract
The objective of this paper is to present a new dynamic permeability model to improve modeling of production from coalbed reservoir. Currently, most modeling approaches for coalbed reservoir permeability only consider one single factor. Little research have been done on parameter sensitivity analysis. We improved the description of coalbed reservoir permeability model by considering effective stress, matrix shrinkage and Klinkenberg effect. To amend the P&M model, the dynamic permeability model is given in the form of piecewise function. Next, parameter sensitivity analysis was taken based on this new model, and the following conclusions were drawn: 1) Large Young's modulus, Poisson's ratio, critical desorption pressure and Langmuir volume strain value have greater improvement effect on permeability; 2) The greater the initial porosity, the smaller the times permeability increase; 3) Klinkenberg effect has more obvious influence on permeability under the condition of lower pressure. This gives us a message: In the whole development process, we should use the dynamic permeability index to adjust and optimize the production system continuously.
Identification of Natural Gas Hydrates in Blocks 25a, 25b, 26 and 27 Offshore Trinidad Using Available Well Log Data
Authors: Smith M. M. , Sobers L. E. 
Published: February 2021

Abstract
Natural gas hydrates can be found in conventional hydrocarbon depositional environments such as clastic marine sediments, siltstones and unconsolidated sands and in oceanic environments for reservoir pressures greater than 663 psi (46 bars) and temperatures less than 20 °C. These conditions are found in the deep water (&gt; 300 m) acreage off the South East coast of Trinidad. Natural gas hydrates have been recovered in this area during drilling and seismic data have shown that there may be deposits in some areas. In this study we reviewed all the available borehole data and employed well log interpretation techniques to identify natural gas hydrates in the deep water acreage blocks 25 a, 25 b, 26 and 27 off the Trinidad South East coast. The analysis of well log data for the given depths did not present evidence to suggest the presence of natural gas hydrates in Blocks 25 a, 25 b, 26 and 27. In this paper we present our analysis of the data available and recommend the formation depths which should be logged in during the deep water exploration drilling to confirm the seismic data and core data which indicate the presence of natural gas hydrates in these blocks.
Case Study for Reducing Tubing Failures in Suriname's Tambaredjo Field
Authors: Nurmohamed D. , Lien H. Chin , Kisoensingh S. 
Published: February 2021

Abstract
In Staatsolie, as of December 2013, there were 1549 shallow wells from its 3 oilfields. One thousand one hundred and thirty (1130) of these were in the Tambaredjo field (TAM field). In the 3 decades of its operations, the prime mechanism for lifting the 15.6oAPI crude to surface has been with progressive cavity pumps (PCP). The down hole pumps are surface driven and installed at an average true vertical depth (TVD) of 1000 ft. Oilfield best practices are employed in the design, installation and operation of the production strings and pumps.
In the period 2008-2012 an average 580 down hole failures occurred annually of which 54% was caused by tubing leaks, with a repetitive frequency of up to 6 faillures per year on individual wells. Visual inspection of internal tubing's have shown that the principal failure mechanism stems from rod tubing wear (abrasion caused by the rotational motion) exacerbated by the corrosiveness of the produced fluids. Most of the tubing wear occurs at the tubing body in direct contact with the rod couplings. It is found that most tubing leakages (up to 70%) occur on the lower part of the tubing string above the pump. Previous installation of shorter rods above the pump, which is causing a high eccentrically movement of the rod string, also increased the occurrences of these failures directly above the pump.
In an effort to reduce these tubing failures, an eight-well pilot program was commenced to install rod guides in wells with the highest failure rate and to install a sucker rod of 25 feet right above the pump. These eight wells were selected based on their high tubing failure rates. Although the program is still being conducted, preliminary results thus far have been quite promising in these wells. In four (4) wells, the work-over frequency was reduced from average 5 to 3 jobs per annum resulting in 40% reduction. The remaining 4 wells are still producing after an average 5-month period without any tubing failures.
This paper presents the approach and strategy used to minimize rod-tubing wear in shallow vertical well applications based on the outcome of the pilot test.
HSE Philosophy and Design Consideration of a Purpose Built Waste Processing Facility
Authors: Kabanov M. , Bruce D. , Mich L. M. 
Published: February 2021

Abstract
Managing, processing and correctly disposing of drill-cuttings that have been contaminated with Oil/Synthetic-Based Drilling Fluids is an integral part of drilling most wells in the North Sea and beyond. While recent advances in offshore treatment capabilities have made approach more reliable in recent times, shipping the waste to specialised onshore facilities remains the preferred choice in many areas. As such, the nature of these treatment centres can have a substantial effect on the overall environmental footprint inherent in drilling a well, as well as the perception of the industry to the public living near such facilities. This paper discusses the process of designing and building a modern, fit-for-purpose and completely compliant waste processing facility in Peterhead, near Aberdeen, UK. While a hammer-mill is at the heart of this process, this paper focusses on the facility housing the hammer-mill rather than the thermal desorption process itself. Key areas of discussion include: initial site selection; external area considerations such as drainage, rainwater re-use and skip storage; internal area features to minimise noise and smell; overall HSE goals and processes including re-use of recovered base oil and disposal options for solid and water waste streams. Furthermore, key lessons learnt and potential future improvements, changes and expansion are touched on.
A dual-band polarization insensitive metamaterial absorber with a single metal square patch for sensing application
Authors: Kang Yongqiang , Wang Jun , Liu Homgmei 
Published: February 2021

Abstract
We proposed a dual-band polarization-insensitive metamaterial absorber consisting of merely the metal square patch and a continuous metal ground separated by a middle dielectric layer. Two resonance peaks derived from `the fundamental resonance (with 97% absorbance) and the surface lattice resonance (with 99% absorbance) are realized. It is different from previous work the dual-band response is obtained by combining two resonances of different sizes. Moreover, a first-order diffraction mode of grating predicted the resonance wavelength of the proposed absorber. The surface electromagnetic field distributions of the unit-cell structure reveal the physical origin of the dual-band absorption. Importantly, the first absorption peak result from surface lattice resonance with narrow line-width has large sensitivity perform and high quality factor, which has significant potential in the application of biosensors and monitoring.
Evaluation of The Standard Procedure For Treatment of Periprosthetic Joint Infections of Total Knee and Hip Arthroplasty: A Comparison of The 2015 and 2020 Census in Total Joint Replacement Centres in Germany
Authors: Osmanski-Zenk Katrin , Klinder Annett , Rimke Christina , Wirtz Dieter C. , Lohmann Christoph H. , Haas Holger , Kladny Bernd , Mittelmeier Wolfram 
Published: February 2021

Abstract
Background Since there are no national or international algorithms there are different procedures for both, the diagnosis and the therapy of a periprosthetic joint infection (PJI). Therefore, the present paper evaluates the respective protocols from different centres on the basis of an EndoCert questionnaire to treat PJI in certified total joint replacement centres (EPZ).Materials and methodsA questionnaire was developed in cooperation with the EndoCert Certification Commission to survey the principles to treat septic revision arthroplasties in EPZ including questions on various treatment options: prosthesis preserving procedures (DAIR - Debridement, antibiotics, irrigation, and retention of the prosthesis), one-stage revision, two-stage revision, removal of the endoprosthesis and sampling prior to reimplantation. All certified EPZ were included (n = 504). The results of the current survey 2020 were compared to those of a previous analysis.ResultsThe number of centres that performed DAIR up to a maximum of 4 weeks and more than 10 weeks after index surgery has clearly decreased since 2015, while the number of centres that provided a one-stage revision as a treatment option has increased (hip: +6.3%; knee: +6.6%). The majority of the centres (73.2%) indicated a 4-8 week period as the interval between prosthesis removal and reimplantation for two-stage replacement for both, hip and knee revisions. Amongst centres with a higher number of revision surgeries (>200 revisions/year), there were even more that opted for the 4-8 week period (92.3%). The Girdlestone situation, but also metal-based spacers with/without reinforcement with antibiotic-containing cement, are less frequently used. When exchanging knee replacements, there was a clear trend towards cemented anchoring, whereas cementless anchorage was preferred for hip replacements. Overall, the number of EPZ with a standardised protocol for the procedure continues to increase. In addition, more samples for microbiological testing are taken when removing the endoprosthesis, 72% of the centres take 5 or more samples.ConclusionWhile there was a trend towards standardised therapeutic algorithms for PJI with more uniform choices among the centres in 2020 compared to 2015, the treatment often remains an individual decision. However, since a consistent treatment regime is of vital importance with an expected rise of total numbers of revision arthroplasties, uniform definitions with regard to comparability and standardisation are necessary for the further development of the EndoCert system.