bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maximizing Stimulation Efficiencies in Offshore Multistage Completions, Black Sea, Romania
Authors: Grubac Gabrijel , Conrad Joel , Janiczek Peter , Alexandru Dragomir , Mcgarvey Sean 
Published: January 2022

Abstract
This paper presents an analysis of the stimulation treatment design and operational efficiencies in the Black Sea. In greater detail, the paper focuses on how the stimulation design and each operational step has been optimized to save time, money and ensure an HSE driven completion methodology.
An analysis was performed on the stimulation design and implementation approach looking at its evolution through a knowledge building and lesson learning process. The principal goal was to determine the most economical way to stimulate an offshore well without making any concessions to the reservoirs’ production or ultimate recovery. From the basics of well and frac design to completion optimization, effort was applied in analyzing ball launching procedures, frac spacing, logistical arrangements on the stimulation vessel and all other areas where there was potential to make improvements. Ultimately, an analysis of fluid displacements during flush was performed and deductions inferred.
Past stimulation treatments were analyzed in an effort of better understanding the advantages and disadvantages in terms of production output of the wells. Similarly, an analysis of the completion approach and operational efficiencies showed the ability of pumping three stimulation stages a day. Considering that horizontal wells in the area are usually completed in six stages, a stimulation campaign would effectively be completed in 2 pumping days, 4 days total if no weather or operational delays are faced. Further improvements of this approach have been implemented in 2021 when six stimulation stages have been pumped in a single vessel ride. Applying the ball drop procedure offshore showed optimal results, as it is efficient in reducing downtime in between fracturing stages and in achieving proper isolation between stimulation zones. Likewise, with over flush being a concern throughout most of the stimulation population, certain cases in the Black Sea showed that over flushing did not adversely affect production of the wells with the production exhibiting ~15% above expected production rates post stimulation. In conclusion, the authors believe that the operational efficiencies achieved in the Black Sea are transposable in other offshore environments and successful cost cutting can be achieved by sound engineering and logistical decisions.
The approach and results are beneficial in understanding where the economics are positively impacted in multistage stimulation treatments in the offshore environments, hence ultimately improving the rate of return.
Fluorescent Microspheres Method Efficiency in Horizontal Wells with Gas Condensate Liquid
Authors: Klimov Mikhail , Ramazanov Rinat , Husein Nadir , Upadhye Vishwajit , Drobot Albina , Novikov Igor , Bydzan Andrei , Gazizov Ruslan , Buyanov Anton 
Published: January 2022

Abstract
The proportion of hard-to-recover reserves is currently increasing and reached more than 65% of total conventional hydrocarbon reserves. This results in an increasing number of horizontal wells put into operation. When evaluating the resource recovery efficiency in horizontal wells, and, consequently, the effectiveness of the development of gas condensate field, the key task is to evaluate the well productivity. To accomplish this task, it is necessary to obtain the reservoir fluid production profile for each interval. Conventional well logging methods with proven efficiency in vertical wells, in case of horizontal wells, will require costly asset-heavy applications such as coiled tubing, downhole tractors conveying well logging tools, and Y-tool bypass systems if pump is used. In addition, the logging data interpretation in the case of horizontal wells is less reliable due to the multiphase flow and variations of the fluid flow rate.
The fluorescent-based nanomaterial production profiling surveillance technology can be used as a viable solution to this problem, which enables cheaper and more effective means of the development of hard-to-recover reserves. This technology assumes that tracers are placed downhole in various forms, such as marker tapes for lower completions, markers in the polymer coating of the proppant used for multi-stage hydraulic fracturing, and markers placed as fluid in fracturing fluid during hydraulic fracturing or acid stimulation during bottom-hole treatment.
The fundamental difference between nanomaterial tracers production profiling and traditional logging methods is that the former offers the possibility to monitor the production at frac ports in the well for a long period of time with far less equipment and manpower, reduced costs, and improved HSE.
Case Study of Condensate Dropout Effect in Unconventional Gas/Condensate Reservoirs with Hydraulically Fractured Wells
Authors: Alsultan Ali H. , Shaoul Josef R. , Park Jason , Zitha Pacelli L. J. 
Published: January 2022

Abstract
Condensate banking is a major issue in the production operations of gas condensate reservoirs. Increase in liquid saturation in the near-wellbore zone due to pressure decline below dew point, decreases well deliverability and the produced condensate-gas ratio (CGR). This paper investigates the effects of condensate banking on the deliverability of hydraulically fractured wells producing from ultralow permeability (0.001 to 0.1 mD) gas condensate reservoirs. Cases where condensate dropout occurs over a large volume of the reservoir, not only near the fracture face, were examined by a detailed numerical reservoir simulation.
A commercial compositional simulator with local grid refinement (LGR) around the fracture was used to quantify condensate dropout as a result of reservoir pressure decline and its impact on well productivity index (PI). The effects of gas production rate and reservoir permeability were investigated. Numerical simulation results showed a significant change in fluid compositions and relative permeability to gas over a large reservoir volume due to pressure decline during reservoir depletion. Results further illustrated the complications in understanding the PI evolution of hydraulically fractured wells in "unconventional" gas condensate reservoirs and illustrate how to correctly evaluate fracture performance in such a situation.
The findings of our study and novel approach help to more accurately predict post-fracture performance. They provide a better understanding of the hydrocarbon phase change not only near the wellbore and fracture, but also deep in the reservoir, which is critical in unconventional gas condensate reservoirs. The optimization of both fracture spacing in horizontal wells and well spacing for vertical well developments can be achieved by improving the ability of production engineers to generate more realistic predictions of gas and condensate production over time.
Impact of Delayed Flowback on Well Performance: Case Study
Authors: Al Shidhani Ruqia , Al Shueili Ahmed , Al Salmi Hussain , Jaboob Musallam 
Published: January 2022

AbstractDue to a resource optimization and efficiency improvements, wells that are hydraulically fractured in the tight gas Barik Formation of the Khazzan Field in the Sultanate of Oman are often temporarily left shut-in directly following a large scale massive hydraulic fracturing stimulation treatment. Extensive industry literature has often suggested (and reported), that this may result in a significant direct loss of productivity due to the delayed flowback and the resulting fracture conductivity and formation damage. This paper will review the available data from the Khazzan Field address these concerns; indicating where the concerns should and should not necessarily apply.The Barik Formation in the Khazzan Field is an over-pressured gas-condensate reservoir at 4,500 m with gas permeability ranging from 0.1 to 20 mD. The average well after hydraulic fracturing produces 25 MMscfd and 500 bcpd against a wellhead pressure of 4,000 psi. A typical hydraulic fracturing stimulation treatment consists of 14,000 bbl of a borate-crosslinked guar fluid, placing upwards of 1MM Lbs of high conductivity bauxite proppant within a single fracture. In order to assess the potential production loss due to delayed flowback operations, BP Oman performed a suite of formation damage tests including core samples from the Barik reservoir, fracture conductivity considerations and dynamic behaviors. Additionally, normalized production was compared between offset wells that were cleaned-up and put onto production at different times after the hydraulic fracturing operations.Core tests showed a range of fracture conductivities over time with delayed flowback after using the breaker concentrations from actual treatments. As expected, enhanced conductivity was achieved with additional breaker. The magnitude of the conductivity being created in these massive treatments was also demonstrated to be dominant with respect to damage effects. Finally, a normalized comparison of an extensive suite of wells clearly showed no discernible loss of production resulted from any delay in the flowback operations.This paper describes in details the workflow and resulting analysis of the impact of extensive shut-in versus immediate flowback post massive hydraulic fracturing. It indicates that the impact of such events will be limited if the appropriate steps have been taken to minimize the opportunity for damage to occur. Whereas the existing fracturing literature takes the safe stance of indicating that damage will always result from such shut-ins, this paper will demonstrate the limitations of such assumptions and the flexibility that can be demonstrated with real data.
Extended-Time Conductivity Testing of Proppants Used for Multi-Stage Horizontal Completions
Authors: Pearson C. Mark , Green Christopher A. , McGill Mark , Milton-Tayler David 
Published: January 2022

Abstract
The American Petroleum Institute Recommended Practice 19-D (2018) is the current industry standard for conductivity testing of proppants used in hydraulic fracturing. Similar to previous standards from both the API and ISO, it continues the practice of measuring a "reference" long-term conductivity after 50-hours of time at a given stress. The fracture design engineer is then left to estimate a damage factor to apply over the life of the well completion based on correlations or experience.
This study takes four standard proppants used for multi-stage horizontal well completions in North America and presents test data over 250-days of "extended-time" at 7,500 psi of effective stress. The API RP 19-D procedure was followed for all testing, but extended for 250-days duration for the four proppant types: 40/70 mesh mono-crystalline "White" sand, 40/70 mesh multi-crystalline "Brown" sand, 100 mesh "Brown" sand, and 40/70 mesh Light Weight Ceramic (LWC). The 7,500 psi stress condition was chosen to replicate initial stress conditions for a 10,000 feet deep well with a 0.75 psi/ft fracture gradient - typical of unconventional resource plays such as the Bakken formation of North Dakota or the Delaware Basin in west Texas. Results presented provide a measure of the amount of damage occurring in the proppant pack due to time at stress.
To the authors’ knowledge, there has never been any extended-time conductivity data published for multiple proppant types over the timeframe completed in this study - despite the obvious need for this understanding to optimize the stimulation design over the full life of the well.
Results for the four proppant types are presented as conductivity curves as a function of time for the 250-days of testing. Pack degradation is shown to follow a semi-log decline. Late time continued degradation for all materials is extrapolated over the life of a typical well (40 years), and compared to extended-time particle size distribution and crush data to explain the results observed.
Extended-time data such as this 250-day study have never been published on proppants such as these despite the fact that fracture conductivity has a major impact on the productive life of a well and the ultimate recovery of hydrocarbons from the formation. The data presented should be of great interest to any engineer involved with completion designs, or reservoir engineers assessing the productive life and ultimate recovery in the formation since economic optimization is primarily driven by the interplay of fracture length/area with extended-time in-situ fracture conductivity.
Eco-Friendly Electric-Powered Hydraulic Fracturing Towards Shale-Gas Recovery: Efficiency, Economics and Field Application
Authors: Tong Zheng , Kuang Yunfan , Fan Chunming , Li Tao , Wang Jiangyang , Li Yiliang , Qian Jie 
Published: January 2022

Abstract
The recovery of unconventional gas fields especially the shale gas is of great significance to clean energy supply. High productivity of shale gas is attributed to the large-scale hydraulic fracturing with high operating pressure (80-100MPa) and discharging rate (14-18m3/min). More high-horsepower fracturing vehicles driven by diesel engines result in higher CAPEX. The low operation efficiency and unexpected maintenance negatively affected the economics performance of operators due to unacceptable OPEX. The fully electric-powered hydraulic fracturing solution was proposed as the alternative to the diesel-engine fracturing vehicles in this article. The skid-based electric pumping units were newly developed with advantages of high power density (6000HP per unit), Variable Frequency Drive (VFD) modules integration, fuel cost saving, low maintenance expenditure and eco-friendly operation. The field application was conducted in one pad of N209 in shale gas field, Sichuan, China.
The electric-powered system, consisting of pumping units and blenders with other facilities, was deployed on the operation site. One large-capacity electric power grid (35kV and 30000kVA) was constructed for both drilling and massive multistage fracturing. The operation team successfully performed all hydraulic fracturing jobs as required with 7.4×105 kWh of total power consumption. The system functioned reliably without large faults occurred.
The electric-powered solution was comprehensively evaluated and compared to the diesel-engine fracturing solution in terms of CAPEX, operational efficiency, power consumption, maintenance and fleet crew cost. The novelty of the technology is the fully electric-powered hydraulic fracturing system with large-capacity electric power grid. It is concluded from the field application that the electric-powered fracturing technology is qualified for unconventional reservoirs development.
Connecting the Dots: Multistage Fracturing in Horizontal Wells with Multilayered Reservoirs - Lessons Learned
Authors: Al Shueili Ahmed , Jaboob Musallam , Al Salmi Hussain 
Published: January 2022

Abstract
Efficient multistage hydraulic fracturing in horizontal wells in tight-gas formations with multilayered and laminated reservoirs is a very challenging subject matter; due to formation structure, required well trajectory, and the ability to establish a conductive and permanent connection between all the layers. BP Oman had initiated the technical journey to deliver an effective horizontal well multistage frac design through learnings obtained during three key pilot horizontal wells. Since these initial wells, additional candidates have been drilled and stimulated, resulting in further advancement of the learning curve.
Many aspects will be covered in this paper, that will describe how to facilitate the most effective hydraulic fracture placement and production performance, under these laminated conditions. These approaches will include the completion and perforation selection, fracture initiation zone selection, fracture height consideration, frac fluid type and design. The paper will go on to describe a range of different surveillance options, including clean-up and performance surveillance as well as number of other factors.
The experiences that have been gained provide valuable insight and learning about how to approach a multistage fracturing horizontal well program in this kind of depositional environment. Additionally, how these lessons can potentially be subsequently adapted and applied to access resources in the more challenging and higher risk areas of the field. For example, this paper will present direct comparison of over and under-displaced stages; differences in execution and production for cased hole and open hole completions; and many other variables that always under discussion for hydraulic fracturing in horizontal wells.
This paper describes in detail the results of many multistage fracturing trials by BP Oman in horizontal wells drilled in challenging multilayered and laminated tight-gas reservoirs. These findings may help to cut short learning curve in similar reservoirs in the Middle East Region and elsewhere.
Worlds First Offshore Horizontal Well Using Jointed Pipe Cemented Frac Sleeve Technology
Authors: Thomson Shaun , Kiyabayev Baglan , Ritchie Barry , Monberg Jakob , De Heer Maurits , Skov List Soren 
Published: January 2022

Abstract
The Valdemar field, located in the Danish sector of the North Sea, targets a Lower Cretaceous, "dirty chalk" reservoir characterized by low permeabilities of &lt;0.5mD, high porosities of &gt;20% and contains up to 25% insoluble fines. To produce economically the reservoir must be stimulated. Typically, this is by means of hydraulic fracturing. A traditional propped fracture consists of 500,000 to 1,000,000 lbs of 20/40 sand, placed using a crosslinked seawater-based borate fluid. The existing wells in the field are completed using the PSI (perforate, isolate, stimulate)1 system. This system was developed in the late 1980s as a way of improving completion times allowing each interval to be perforated, stimulated and isolated in a single trip and has been used extensively in the Danish North Sea in a variety of fields. The system consists of multiset packers with sliding sleeves and typically takes 2-3 days between the start of one fracture to the next.
Future developments in this area now require a new, novel and more efficient approach owing to new target reservoir being of a thinner and poorer quality. In order for these new developments to be economical an approach was required to allow for longer wells to be drilled and completed allowing better reservoir connectivity whilst at the same time reducing the completion time, and therefore rig time and overall cost.
A project team was put together to develop a system that could be used in an offshore environment that would satisfy the above criteria, allowing wells to be drilled out to 21,000ft and beyond in excess of coiled tubing reach. The technology developed consists of cemented frac sleeves, operated with jointed pipe, allowing multiple zones to be stimulated in one trip, as well as utilizing a modified BHA that allows for the treatments to take place through the tubing, bringing numerous benefits.
The following paper details the reasons for developing the new technology, the development process itself, the challenges that had to be overcome and a case history on the execution of the first job of its kind in the North Sea, in which over 7MM lbs of sand was pumped successfully, as well as the post treatment operations which included a proof of concept in utilizing a tractor to manipulate the sleeves. Finally, the production performance will be discussed supported by the use of tracer subs at each of the zones.
Experimental Study on Phase Conjecture Based on Two-dimensional Image and Carrying Three-dimensional Image With Mist in Electro-holographic Reconstruction *
Authors: Zhi-xiong ZHAO , Hua ZHANG , Qing-yun Kuang , Bo Li , Lin Hu 
Published: January 2022

Abstract
A method is proposed for phase conjecture based on the intensity curve of a two-dimensional(2D) image by computing a polynomial equation. The intensity values of the 2D image, which represents the distance between the image detectors and the three-dimensional(3D) scene is converted to phase information by our method. The results of numerical calculation with phase conjecture are analyzed. And what’s more, the numerical reconstruction results with phase information obtained as initial phase factors of a complex object for Fresnel kinoform and dynamic pseudorandom-phase tomographic computer holography(DPP-TCH) are compared. The peak signal-to-noise ratio(PSNR) and correlation coefficient (CC) between the reconstructed images and original object are analyzed. An experimental system is designed for photoelectric holographic reconstruction based on phase-only liquid crystal spatial light modulator(LC-SLM) and mist screen. The electro-optical experimental results indicate that suppressed the speckle noise 3D images that can be observed with naked eye have been obtained.
Comprehensive Multi-cohort Transcriptional Meta-analysis of Muscle Diseases Identifies a Signature of Disease Severity
Authors: Walsh Christopher James , Batt Jane , Herridge Margaret , Mathur Sunita , Bader Gary D , Hu Pingzhao , Khatri Purvesh , Santos Claudia Dos 
Published: January 2022

Abstract
Muscle diseases share common pathological features suggesting common underlying mechanisms. We hypothesized there is a common set of genes dysregulated across muscle diseases compared to healthy muscle and that these genes correlate with severity of muscle disease. We performed meta-analysis of transcriptional profiles of muscle biopsies from human muscle diseases and healthy controls. Studies obtained from public microarray repositories fulfilling quality criteria were divided into six categories: i) Immobility, ii) inflammatory myopathies, iii) ICU acquired weakness (ICUAW), iv) congenital muscle diseases, v) chronic systemic diseases, vi) motor neuron disease. Patient cohorts were separated in discovery and validation cohorts retaining roughly equal proportions of samples for the disease categories. To remove bias towards a specific muscle disease category we repeated the meta-analysis five times by removing data sets corresponding to one muscle disease class at a time in a “leave-one-disease-out” analysis. We used 636 muscle tissue samples from 30 independent cohorts to identify a 52 gene signature (36 up-regulated and 16 down-regulated genes). We validated the discriminatory power of this signature in 657 muscle biopsies from 12 additional patient cohorts encompassing five categories of muscle diseases with an area under the receiver operating characteristic curve of 0.91, 83% sensitivity, and 85.3% specificity. The expression score of the gene signature inversely correlated with quadriceps muscle mass (r =-0.50, p-value = 0.011) in ICUAW and shoulder abduction strength (r=-0.77, p-value = 0.014) in amyotrophic lateral sclerosis (ALS). The signature also positively correlated with histologic assessment of muscle atrophy in ALS (r=0.88, p-value=1.62x10−3) and fibrosis in muscular dystrophy (Jonckheere trend test p-value = 4.45 x 10−9). Our results identify a conserved transcriptional signature associated with clinical and histologic muscle disease severity. Several genes in this conserved signature have not been previously associated with muscle disease severity.