bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Integrated Study of Probabilistic Formation Evaluation and Geomechanical Analysis to Investigate the Potential of Hydraulic Fracture Stimulation in Najmah Unconventional Shale Reservoirs
Authors: He Ting , Hornbrook John W. , Dharanidharan Bala , Al-Bahar Mohammad , Al-Sane Amal , Suresh Vandana , Hickey James J 
Published: October 2019

AbstractThe Najmah Shale, an organic-rich marl, is generally considered the primary source rock for hydrocarbons in Kuwait’s Jurassic and Cretaceous reservoirs. The purpose of this study was to estimate the original hydrocarbons in place (OHIP) and the geomechanical properties of the Najmah reservoir to aid in the design of a hydraulic fracture stimulation program in West Kuwait.An integrated petrophysical evaluation utilized conventional and sidewall core measurements, and standard and advanced open-hole logs were used to estimate net pay, porosity, oil saturation, and geomechanical properties. Formation evaluation of the Najmah Shale as a potential unconventional reservoir posed numerous challenges. These challenges included the ambiguous effects that high total organic carbon (TOC) has on conventional porosity logs and resistivity logs and the associated shale volume estimations. In this study, a probabilistic multi-mineral model was developed to more accurately assess the TOC of the rock and the associated porosity, saturation, and clay volume. Advanced well logs, including spectral gamma ray and elemental spectroscopy logs, were used to improve the mineralogical model of the complex formation. Routine core analysis, programmed pyrolysis, and X-ray diffraction (XRD) analyses were used to verify and calibrate the multi-mineral model results. Since a dual-porosity system was present in the formation, the Simandoux saturation equation was used to evaluate the fluid saturations. Anisotropic horizontal stress profiles were developed for specific wells based on analysis of dipole sonic logs, resulting in a greater regional understanding of the target interval.Based on the results of the multi-mineral modeling, the average TOC of the Najmah Shale varies from well to well throughout West Kuwait, with values as high as 14.8%. The effective porosity of the Najmah Shale ranges from 1 to 8%. Water saturation is low for these organic-rich formations. Water zones may occur above or below the organic-rich interval depending on the location. The geomechanical properties of the Najmah Shale are conducive to hydraulic fracture stimulation, by analogy to proven productive shale plays. The Sargelu interval, below the Najmah Shale, exhibits distinctly higher minimum horizontal stress gradients while the limestone above the Najmah Shale presents a weaker stress barrier.The results of the probabilistic formation evaluation of the Najmah Shale indicated that a significant volume of hydrocarbons is present in the formation. The geomechanical properties of the Najmah and adjacent units are conducive to successful hydraulic fracture stimulation. The evaluation of water-bearing zones adjacent to the target formation is critical to the investigation of the formation’s stimulation potential.
A New Algorithm to Quantify the Productivity of Hydraulically Fractured Horizontal Gas Wells
Authors: Mohamed Abdelmjeed , Abdalla Mohamed , Alnuaim Sami 
Published: October 2019

AbstractMulti-stage hydraulic fracturing is considered as a solution to low-productivity wells when the reservoir properties are not good enough to produce oil or gas naturally. The Inflow Performance Relationship (IPR) is the most common method used to evaluate well productivity. Many models have been introduced to estimate the IPR for horizontal wells. However, a significant error will result when they are applied for fractured horizontal wells. This work introduces a new IPR model to estimate gas production rates from multi-stage hydraulically fractured horizontal gas wells at different well pressures.A single-horizontal-well simulation model was built to generate the production data, and several scenarios were created by changing different parameters, such reservoir permeability anisotropy and fracture properties (fracture dimensions, conductivity, and the number of fractures) to determine the parameters that significantly affect gas production rates from such wells. After the effective parameters were determined, 70% of the resultant data was used to develop the new IPR model using nonlinear regression techniques, while 30% of the data was used for testing. Afterward, a statistical study was performed to evaluate the proposed model to ensure its accuracy in estimating gas production rates using different statistical means, such as R-squared, mean percentage error, variance, and standard deviation.The term dimensionless conductivity was introduced to simplify the model. This term is a combination of reservoir permeability, fracture half-length, and fracture conductivity. The gas production rate was found to be a strong function of the ratio between vertical and horizontal permeability, the number of fractures, and fracture conductivity, while the height of the fracture and the half-length had no significant effect on the dimensionless IPR curve. The new model showed an excellent performance in estimating gas production rates for hydraulically fractured horizontal wells with a mean percentage error of 3.06% and R-squared of 0.9966.This study introduced a new simple and reliable IPR model that accurately estimates the gas production rates from multi-stage hydraulically fractured horizontal gas wells at different flowing bottom-hole pressures.
Optimization of Development of Heavy Oil Reservoirs through Geochemical Characterization
Authors: Canbaz Celal Hakan , Deniz-Paker Melek , Hosgor Fatma Bahar , Putra Dike , Moreno Raul , Temizel Cenk , Alkouh Ahmad 
Published: October 2019

AbstractGeochemistry is not only a well-known tool in providing a better understanding of the distribution of fluids in the reservoir rock but also an efficient kit in developing reservoir by decreasing the uncertainty throughout the characterization process. Utilizing geochemistry, not only efficiently identify the fluids and type of oil alteration drastically laterally and vertically over short distances in heavy oil reservoirs where such differences are of significant importance in production of heavy oils in these already challenging reservoirs, but also outline the value of geochemistry to justify the value of information in the process of more robust reservoir characterization and management of heavy oil reservoirs.A conceptual model representative heavy oil reservoir recovery is utilized to compare the recoveries between a case where geochemistry is applied to characterize the reservoir and another case where geochemical methods are not employed by using a full-physics commercial reservoir simulator. A sensitivity and optimization software is coupled with the reservoir simulator to outline the relative significance of the important parameters in the recovery process.Geochemical characterization, not only, provides information on gas content and its likely behavior where it can also lead to better decisions on completion strategies to avoid zones of different viscosity, but also the essential correlation between the geochemistry and the thermodynamics of heavy oil. Comprehensive reservoir characterization leads to a more robust identification of reservoir fluids where such knowledge will greatly enhance the efficiency thus the economics of the process that is especially important in low oil price environments. There is lack of studies recently on the application of geochemical characterization on the recovery of the process analyzing the relative significance of components, key drivers and the value of the information throughout the process, even though some authors have been published their research on geochemistry and its use in the characterization of the reservoirs. Our study outlines a comprehensive background including latest developments, investigates the key factors, and the value of information on comparative cases considering the relevant components of the process.
New Robust Model to Evaluate the Total Organic Carbon Using Fuzzy Logic
Authors: Mahmoud Ahmed Abdulhamid , Elkatatny Salaheldin , Ali Abdulwahab , Abouelresh Mohamed , Abdulraheem Abdulazeez 
Published: October 2019

Abstract
Total organic carbon (TOC) is an essential parameter used for unconventional shale resources evaluation. The current methods for TOC determination are based on conducting time-consuming laboratory experiments or by using empirical correlations; the later are developed based on assumptions that restrict their applicability. This study provides a new robust model for TOC estimation based on conventional well logs. The model was developed using an adaptive neuro-fuzzy inference system with subtractive clustering (ANFIS-SC).
Four conventional well logs of deep resistivity, sonic transit time, gamma ray, and formation bulk density collected from Barnett shale formation were used to develop the ANFIS-SC model for TOC estimation. A dataset consists of 645 records of the four well logs and TOC were used to develop the new model. The model was optimized for the different combinations of the ANFIS-SC’ design parameters and for training/testing data ratio. The optimum predictability of the ANFIS-SC TOC model was reached after 400 iterations using a cluster radius of 0.3 and a training/testing data ratio of 70/30.
The statistical analysis showed that TOC is a strong function of the bulk density, moderate function of the sonic transit time and gamma ray, and a weak function of the deep resistivity. The training and testing results proved that the developed ANFIS-SC model is able to predict the TOC based on the four mentioned well log data with high accuracy. For the training data set, the TOC was estimated with an average absolute percentage error (AAPE) of 8.62%, a coefficient of determination (R2) of 0.91, and a correlation coefficient (R) of 0.96. For the testing data set, the associated AAPE in predicting the TOC is 9.57%, while R2 and R between the actual and predicted TOC are 0.89 and 0.94, respectively.
Laboratory Study on Polymer Mechanical Degradation in Carbonate Core Plugs Versus in Capillary Tubes
Authors: Cao Dongqing , Han Ming , Leng Zhenpeng , Wang Jinxun 
Published: October 2019

AbstractPolymer mechanical degradation can be induced by high flow rate during the injection in subterranean formations, especially near-wellbore regions. This work presents a study on the polymer injection in carbonate core plugs and capillary tubes at different injection rates in order to assess the critical shear rates beyond which significant polymer degradation takes place. The polymer degradation process in capillary tubes is correlated with that in the carbonate core plugs, which facilitates the degradation assessment.A semi-dilute polymer solution in synthetic injection water was injected into carbonate and sandstone core plugs with different permeabilities and length. The collected effluent solutions were monitored by viscosity measurement using a rheometer and molecular weight distribution measurement using gel permeation chromatography (GPC). Similar procedures were followed for the polymer mechanical degradation using capillary tubes with inner diameters of 0.12, 0.254 and 0.508 mm.Flow in porous media induced severe polymer degradation at a flow rate above the critical shear rate. The carbonate cores showed lower critical shear rates than the sandstone cores. For carbonate core plugs with permeability 390md and 60md, the critical flow rate was 20mL/min corresponding to a shear rate of 4402.1 s-1 and 2mL/min corresponding to a shear rate of 1122.2 s-1. For the sandstone core plugs with permeability 490md and 40md, the critical flow rate was 10mL/min corresponding to a shear rate of 2198.0 s-1 and 1mL/min corresponding to a shear rate of 771.5 s-1. It was observed that greater polymer degradation appeared in the flow through the lower permeability core plugs. Core length had limited effect on the degradation. The average molecular weight became smaller while the molecular weight distribution became wider for the polymer solutions after the mechanical degradation, indicating the irreversible fragmentation of polymer molecules. In comparison, polymer degradation in capillary tubes appeared at a critical shear rate in the magnitude of 200,000 s-1. Similar with the scenarios of polymer injection in core plugs, greater viscosity loss happens in the flow through smaller capillary diameter. By the correlation, the polymer degradation in carbonate core plugs can be predicted by the measurement in the capillary tubes.This work provides the insight of polymer mechanical degradation in carbonate matrix. An easy-to-operate method on the evaluation of polymer mechanical degradation was developed to assist in the operation of the polymer injections.
Utilising Advanced Mud Gas Assessment SATLOG for De-Risking in Business Development
Authors: Pedersen Rasmus , Opsal Jan Gunnar , Kråkenes Kristian , Harrison Darrell 
Published: October 2019

Abstract
A case study is presented, by KUFPEC Norway AS in cooperation with Searcher Geoservices AS, introducing an advanced mud gas evaluation workflow (SATLOG). Results from well analyses are used to aid in the screening, ranking and prioritising of business development opportunities in a strategically important KUFPEC core area in the Norwegian North Sea.
The unique SATLOG approach is based on the reprocessing of digitised mud log well data (gases, C1 to C5) along with analysis of available drilling parameters, core data, and both seismic and wireline log interpretation.
The background for this study is a new ventures and business development initiative in a KUFPEC core area close to the Gina Krog and Sleipner Fields in Norway.
In summary, these SATLOG interpretations can aid in re-classifying well results and highlight one missed discovery and indicate a number of wells may have missed oil pay. This information is vital to the in-house KUFPEC Norway evaluation and prioritising of business development opportunities in the area.
The SATLOG (advanced mud gas) assessment was performed on multiple wells, with a focus on the chemical signature present in producing fields and discoveries. This was followed by a detailed comparison to the wells containing oil shows and wells stated to be dry. In the study area, several wells are formally defined as dry with no shows, however, the SATLOG study indicates that some of these dry wells could hold significant hydrocarbon saturation in missed pay and up-dip accumulations on the scale of 100-150 million barrels STOIIP.
In addition, the SATLOG assessment highlights that some areas can be deemed to be of limited interest as lateral barriers or ineffective migration paths are clearly indicated.
The novel aspect of utilising SATLOG together with seismic and wireline interpretation is the ability to cost effectively re-interpret existing data and gain new and vital knowledge of upside potential in new ventures and business development initiatives in strategically important core areas.
Downhole Energy Harvesting From an Isothermal Well Zone by Converting a Differential Pressure into a Differential Temperature and Combining Thermo-Generators for Smart Well Completions
Authors: Noui-Mehidi Mohamed Nabil , Rizq Ahmed 
Published: October 2019

Abstract
The present paper is concerned with a new method for downhole energy harvesting from an isothermal well zone. It is shown that in a horizontal well compartment where there is thermal equilibrium, the pressure differential between the sand face and the wellbore can be converted into temperature differential using a vortex tube system. The flow, pressure and temperature measurements using the vortex tube in a physical model are correlated to the amount of energy generated with different pressure ranges expected in the well environment. The data reveal that the energy generated can charge substantially a battery to operate downhole sensors and control devices.
Geologic, Seismic, Climatic and Oil Production Controls on Hydrocarbon Seepages at Al-Ahmadi Town, South-Eastern Kuwait
Authors: Ibrahim Muhammad W 
Published: October 2019

AbstractA series of explosions destroyed several houses at Al-Ahmadi Town in southeast Kuwait during 2010 and 2011; they were initially attributed to gas leakages from discarded old domestic gas supply system. The incidents led Kuwait Oil Company (KOC) to commission a surface geochemical survey of one of KOC's Al-Ahmadi housing blocks which was affected by the explosions. A serious gas explosion in Al-Ahmadi on the 18th of May 2015 prompted an evacuation of a number of Al-Ahmadi houses, followed by a prolonged investigation of the source(s) of the recurrent gas leakages. This paper is a review of the published surface geology, subsurface stratigraphy, seismic structural motives and consequences of prolonged production operations of Greater Burgan Oil Field (with special focus on the surface and subsurface stratigraphy and structure of the Al-Ahmadi Ridge of Greater Burgan Oil Field, which is situated beneath the afflicted Al-Ahmadi Town) in search of natural seepage(s) rather than man-made leakage(s) of the exploding gas. The review revealed that the gas explosions were not likely caused by trapped gas in the discarded domestic gas supply network, and argue for an imperfect Greater Burgan oil trap, with inherent ancient oil and gas seepages propagated by environmental side effects of prolonged oil production operations, which attained recurrent cycles in response to climatic seasons, and probably amplified by the occasional regional earthquake seismic waves. The review concludes that under current environments and production practices, the historic trend projects an increase in the volume and number of gas seepages sites over and beyond the footprint of Greater Burgan Oil Field. Furthermore, the review recommends some habitat gas seepage mitigation measures and the deployment of mobile technologies for regular surveying and monitoring of Methane and H2S build-up in the air, and in the shallow subsurface reservoirs below the Ahmadi Town as routine risk management procedures.
Overview of Tracer Applications in Oil and Gas Industry
Authors: Tayyib Deena , Al-Qasim Abdulaziz , Kokal Sunil , Huseby Olaf 
Published: October 2019

AbstractTracer technology is an efficient and effective monitoring and surveillance tool with many useful applications in the oil and gas industry. Some of these applications include improving reservoir characterization, waterflood optimization, remaining oil saturation (Sor) determination, fluid pathways, and connectivity between wells. Tracer surveys can be deployed inter-well between an injector and offset producer(s) or as push-and-pull studies in a single well.Tracers can be classified several ways. (a) Based on their functionality: partitioning and passive tracers. Partitioning tracers interact with the reservoir and thus propagate slower than passive tracers do. The time lag between the two types can be used to estimate Sor, to ultimately assess and optimize EOR operations. (b) Based on their carrying fluid: water and gas tracers. These can be used in IOR or EOR operations. All gas tracers are partitioning tracers and the most common are perfluorocarbons; they are thermally stable, environmentally friendly, have high detectability and low natural occurrence in the reservoir. On the other hand, water tracers are passive tracers and the most commonly used ones are fluorinated acids. (c) Based on radioactivity: radioactive and non-radioactive tracers. Selecting a tracer to deploy in the field depends on a number of factors including their solubility, fluid compatibility, background concentration, stability, detectability, cost, and environmental impact.This paper provides an overview of various tracer applications in the oil and gas industry. These will include the single-well tracer test (SWCT), inter-well tracer test (IWTT), nano tracers, gas tracers and radioactive tracers. Their use will be highlighted in different scenarios. Field case studies will be reviewed for all types of tracers. Lessons learnt for all the applications, including what works and what does not work, will be shared. Specific cases and examples will include the optimization of waterflood operations, remaining oil saturation determination, flow paths and connectivity between wells, and IOR/EOR applications. The current state-of-the-art will be presented and novel emerging methods will be highlighted. This paper will showcase how the tracer technology has evolved over the years and how it shows great potential as a reservoir monitoring and surveillance tool.
Benchmarking Well, Reservoir and Facility Management WRFM Performance in Greenfield Heavy Oil Assets
Authors: Gonzalez Santiago , Gomez Fernando , Gonzalez Gregorio , Montero Jacobo 
Published: October 2019

Abstract
The paper describes the results of a benchmarking exercise conducted for a selected set of Well Reservoir and Facility Management (WRFM) Key Performance Indicators (KPIs) on two greenfield, heavy oil assets in Kuwait. The purpose of the benchmark exercise was to define a baseline performance for these new heavy oil assets to validate ongoing improvement efforts, as well as to identify further improvements opportunities the medium term.
The assets were compared against a group of analogue assets operated by an IOCs. The benchmarking exercise focused on four areas common to all assets: Production Optimization Gains, Well Stock Reviewed, Total Deferment from Wells and Data Acquisition Compliance. Given the differences in conceptual definitions employed by the companies (including the definition of the KPIs, and even the definition of an "asset"), the study started by formalizing the definitions based on the IOC standard. Given that the WRFM processes had only been formally implemented in the Kuwait heavy oil assets in 2018, the data collection was limited to 2018. The greenfield nature of the assets presented some challenges due to different approaches in measurements and the ongoing implementation of the WRFM processes which required normalization of the data to make the comparison effective.
Analysis of the benchmark results indicate that the heavy oil assets in Kuwait have an acceptable performance versus the IOC assets, particularly in Production Optimization Gains and Data Acquisition Compliance. However, the performance is mostly driven by the nature of the asset (Greenfield, early production life) and the relatively small number of wells compared to the IOC assets, which are more mature. The assets required additional focus on well stock reviewed and reduction of the total deferment from wells. By increasing the well stock coverage, more optimization opportunities would be identified and eventually executed. Deferment (mostly due to Sand production and availability of equipment) required urgent attention based on the larger difference in this KPI with the benchmarking group. A set of recommendations per KPI was defined to support the improvement efforts, which are expected to positively impact the performance of the Kuwaiti assets and to maximize the value at their early production stages.
Benchmarking of greenfield assets, particularly in heavy oil, presents various challenges associated with the early stages of operation (and the implementation of WRFM processes), as well as with the actual measurement of performance when compared to more matured assets. The paper is expected to provide a valuable reference for new heavy oil projects, either under definition or in early production, to focus WRFM efforts and accelerate their performance toward top quartile.