bluuebunny/crossref_metadata_2025_split huggingface dataset:
Borehole Breakout Modeling and Stress Profiling Using Anisotropic Mechanical Properties: Case Study in a Tight Basement and Overlying Formation
Authors: Moronkeji Dee , Cazeneuve Eduardo , Franquet Javier , Sandia Marianella Rojas , Velo Diego 
Published: September 2015

Abstract
Optimizing the drilling and completion phases of a typical oil or gas wellbore requires geomechanical analysis to characterize the in-situ stresses. Stress profiles and lateral tectonic stresses can be determined and calibrated through MicroFrac testing and by modeling borehole breakouts observed in borehole image logs.
Several wells in the Campamento 1 field (the first field in the Neuquén Basin) were drilled with the tight basement formation in the Neuquén province in Argentina as the primary target. These wells were evaluated to estimate the stress profile using anisotropic mechanical properties and to identify suitable intervals to fracture. There are several tests and analyses that can typically be used to calibrate horizontal stresses. These tests and analyses include leak-off test (LOT), extended leak-off test (XLOT), minifrac test, step-rate-injection test (SRT), MicroFrac test, core strain measurement (Anelastic Strain Recovery, ASR), analysis of borehole breakouts and induced fractures from specific image logs.
The objective of this paper is to show the use of borehole breakouts and hydraulically induced fracture initiation and closure pressures to calibrate the magnitude of the horizontal stresses in a vertical well. Breakouts are typically more visible in an acoustic image log and are expected to occur in formations with lower strength and/or lower internal friction coefficient but sometimes they occur in intervals with high strength and stiffness sustaining high horizontal tectonic stresses.
Examples are shown in the Campamento 1 field wells with borehole breakouts and minifrac data used in constraining the magnitude of the lateral tectonic strains. The horizontal stress profiles obtained from these vertical wellbores provide valuable information for predicting hydraulic fracture geometry, propagation and containment for subsequent reservoir stimulation jobs. Two vertical wells where coupled calibration with minifrac data and breakout modeling were done are presented to show how this calibration is achieved and how it helps to constrain the magnitude of the horizontal stresses in a vertical well.
The results show how observed borehole breakouts and fracture pressures can help in constraining the magnitude of the lateral tectonic strains. These are important parameters in estimating the horizontal stress profile in the target reservoir and the stress contrast over the sub-adjacent and supra-adjacent formations.
Value of Multiple Production Measurements and Water Front Tracking in Closed-Loop Reservoir Management
Authors: Barros E. G. , Leeuwenburgh O. , Hof P. M. , Jansen J. D. 
Published: September 2015

Abstract
This paper extends previous work on value of information (VOI) assessment in closed-loop reservoir management (CLRM) to estimate the added value of performing multiple measurements along the producing life of the reservoir. The new procedure is based on the workflow from our previous paper which allows to quantify the VOI of a single observation under geological uncertainty. Here we show that, by modifying that workflow slightly, it is possible to assess the value of a series of measurements without a prohibitive increase in computational costs. The approach is illustrated with two cases based on a simple water flooding problem in a two-dimensional five-spot reservoir: the first one, in which we assess the value of a series of production measurements, and the second one, in which we estimate the additional value of water front positions tracked by an interpreted time-lapse seismic survey. We believe that our proposed workflow is a complete methodology to estimate the VOI in a CLRM context because we take into account that the production strategy is updated periodically after new information has been assimilated in the models. However, future work will be required to reduce the computational load to allow for the application of the workflow to real field cases.
Automatic Well Completions and Reservoir Grid Data Quality Assurance for Reservoir Simulation Models
Authors: Al-Zahrani Tariq , Al-Mulla Muath , Al-Nuaim Mohammed 
Published: September 2015

Abstract
Reservoir simulation engineers have to go through an intense and time consuming process to manually quality check large amounts of data which consist of wells, logs and completion events for more than 50 years of history. It is fundamental that data used in building reservoir simulation models is quality controlled and cross-checked to eliminate inconsistencies during the history match process.
This new implemented method will give an overview of the simulation data quality workflow design and outline the development of a state of the art software package that guides engineers through the quality checking process as the first stage of simulation model construction.
We have developed a workflow software package that covers most of the data required for building simulation models. The preparation and validation of data is conducted using tailored automated workflows that guide engineers through the quality control steps in a streamlined manner. At every step, specific data is reviewed and validated based on some well-developed quality check (QC) criteria. In case of any inconsistencies, the software issues relevant error and warning messages and recommends possible remedial solutions or actions.
This tool eliminates tedious manual nonformal effort and results in high-quality simulation models checked and verified through formal and automated workflows, therefore. The new workflow/software reduces the checking process from weeks to days or hours and hence minimizes the overall time to perform history matching.
Exploring the Upside Potential of Ras El Ush - A Mature Producing Field, its Challenges and Solutions
Authors: Patnaik Golak , Abhishek Karmesh , Naser Khafagy Abdel , Attia Wael , Walia Samir K. , Abd-Allah Mohammed 
Published: September 2015

Abstract
The Gulf of Suez is characterized by intensive normal faulting related to rifting of the Red Sea. The Ras El Ush (REU) field displays the same pattern. The field itself is bound on its eastern margin by large NW-SE oriented normal faults dipping NE (towards the Red Sea) and has dip closure to the west. However the nature of the northern and southern boundaries is unclear and they could be limited either by fault or dip terminations.
The REU field has been producing since 1996 from the Nubia and Matulla formations and it currently has around a 26% recovery factor. Nubia and Matulla are isolated from the bottom water aquifer by tarmat layer that acts as a barrier. The field therefore exhibits depletion drive with a sharp pressure decline initially then a secondary gas cab expansion drive.
The objective is to optimize pressure maintenance in the developed blocks either by using Gas Injection or Water Interjection and to evaluate the upside potential using an integrated reservoir management study approach and leveraging advance tools, technologies and best practices.
Since the structure contains dipping beds (up to ~50 deg) and faults, the conventional seismic does not help in interpreting reservoir units and dipping faults. Some of the vertical faults can be picked from seismic. In this case, it's critical to quantify the structural uncertainty due to lateral movement of faults and vertical movement of horizons, particularly near the oil water contact.
Upscaled Pseudo-porosity Extracted from Impedance Volume Can Effectively Predict Gas Fingering in a Dynamic Model – a Gas Injection Case Study
Authors: Namdarian Fatemeh , Taghanaki Morteza Aghababaee , Hashemi Abolfazl 
Published: September 2015

Abstract
Gas injection in an unsaturated carbonate reservoir which is located in south-west of Iran started in 2009, and based on the original dynamic model the gas breakthrough would not have happened earlier than 2017. However, the gas oil ratio (GOR) in some wells increased rapidly before the anticipated time; also the real field data shows different behaviors of gas breakthrough in different wells.
The 3D Geocellular grid obtained from 3D seismic cubes was applied to dynamic model, and by making the size of the cells smaller, the heterogeneity was identified as the most important factor in modeling and monitoring the gas movement from the injected wells towards the production wells. Based on the new upscaling, two dynamic models were constructed. The original model had 267,000 grid cells and the new ones have 1,120,000 and 2,400,000 grid cells respectively. Running the new models illustrated the gas breakout from some wells mostly through one layer of the reservoir. Since effective porosity was estimated by collocated cokrigging of well data with seismic porosity, vuggy porosity distribution in this layer is correctly predicted, given that a karstic volume has been detected in some part of the reservoir which its boundary has been defined by seismic data and the cross-plots of neutron porosity with acoustic impedence validate the reliability of this karstic zone. The results show various types of vuggy porosity that mostly governs the productivity of the wells in this reservoir.
As a result of this study, both dynamic and static models modified based on pseudo-porosity derived from seismic cubes as the best known distributed heterogeneity in this field to predict the gas movement in the reservoir. Based on this modeling, new maximum efficient rates were defined for wells and field development strategy was reconsidered.
Tapping Marginal Resource into Reality: A Case Study in Economically Developing a Low Resistivity Deep Thin Pay Reservoir, Tarim Basin West China
Authors: Li Ning , Li Qiang , Yang Pei , Zhou Bo , Liu Ruiying , Guo Xinyong , Wen Zhang , Xia Guofeng , Lin Xin , Kok Jeffrey , Yen Han Shim , Wang Yong , Liu Yanmei , Wu Bohong , Wang Xiongfei , Sun Qigang , Geng Gan 
Published: September 2015

Abstract
The study area is a marginal oilfield with tilted oil-water-contact. The target reservoir is located more than 5000m deep with an oil column of merely 1m. The primary challenge is to accurately land the well in this thin interval without penetrating the water zone. Faced with complex lithology in a low resistivity pay zone, formation evaluation poses obvious complications. Steering the production lateral within the thin oil column, while performing real-time reservoir evaluation, is the key to succeed economic objectives.
A combined while-drilling technology, including multi-layer bed-mapping and multi-function Logging-While-Drilling (LWD) tools were employed to address these challenges and by the end of 2014, the pilot project had successfully placed the lateral within the target zone, securing an in zone Key-Performance-Indicator (KPI) ratio of over 90% despite encountering lateral heterogeneity. By achieving this KPI, the drilling cycle was shortend by almost one-third. The authors believe that the fit-for-purpose solution can be applied in similar blocks to achieve repeated success.
Reservoir Monitoring Using Streaming Potential; Is the Thermoelectric Correction Necessary?
Authors: Jaafar M. Z. , Ahmed T. , Sulaiman W. R. , Ismail A. R. 
Published: September 2015

Abstract
Wellbore streaming current and their applicability in the location of subsurface sand bodies were discovered in 1931 and the usefulness of this measurement has persisted to the present day. Through the endeavor of many researchers, knowledge and understanding of streaming potential (SP) have slowly evolved from the original mere recognition of its existence to its present-day quantitative use in many applications such as Enhanced Oil Recovery (EOR), water flooding, intelligent wells, etc. The spontaneous potential acts to maintain overall electroneutrality when a separation of electrical charge occurs in response to gradients in pressure (Electrokinetic), chemical composition (Electrochemical), or temperature (Thermoelectric). In spite of it being discovered 70 years ago, unfortunately little work has been done to find measurable value especially for thermoelectric coupling coefficient. Many researchers attempt to generate a universal model for SP. They attributes the limitations (if any) of their model to the scarce availability of accurate estimation for coupling coefficient. This study measures the value of thermoelectric coupling coefficient for five rock samples saturated with 0.01M (NaCl) saline brine. The study takes account of temperature dependant electrode effect. The result shows value of 0.2 mV/K, which is in a good match with most of the published data. It was also found that there is no strong correlation between the thermoelectric coupling coefficient and porosity. The measured thermoelectric values are considered insignificantly small compared to the electrokinetic effect in the system.
Developing A Two-scale Fracture Model And Its Application For Drilling Strategy In A Fractured Carbonate Reservoir
Authors: Changrong Bian , Wang Yi , Feng Xingqiang , Zhang Yu , Li Zhihua , Shen Feng 
Published: September 2015

Abstract
In this study, we present an integrated approach to develop a two-scale fracture model for the Ordovician carbonate fractured reservoir in the Yubei area. The objective of this study is to provide new insights into the impact of fractures on oil production and to recommend drilling strategy. Fractures are characterized by using log data, 3D seismic attribute, borehole image logs and reservoir production data. Image logs illustrate that the dominant reservoir fractures trending in the NE direction parallel to the present-day maximum horizontal compressive stress and are consistent with the major fault system. The electrofacies generated with conventional logs are calibrated into different fracture units by using borehole image logs and reservoir dynamic data. The dynamic behavior of the complex matrix and fracture system is characterized for fracture units at wells. For layer bound diffuse fractures, the fracture properties are modeled statistically set by set with borehole image logs, fracture seismic facies volume representing degree of the fracturation and seismic geometric attribute. Fracture lineaments at the corridor scale are extracted directly from edge-enhanced seismic attribute. Fracture lineaments are cleaned and meshed to define their topology relationships to construct a comprehensive DFN (Discrete Fracture Network) model. Fracture networks are characterized deterministically, which constitute a unique fracture model on the reservoir scale. DFN model provides a geological representation how these fractures are spatially organized in the subsurface and how they may enhance or inhibit fluid flow. The final fracture model honored the two scale fracture models. Grid-cell permeability properties are derived from the two-scale fracture model. Based on the dynamic behavior of fracture units, fracture properties are calibrated against the dynamic data. Our results show that NE orientated fractures are open and conductive. The high productivity zones are characterized by high permeability located in the vicinity of faults. Enhanced oil recovery operations could be optimized using production wells oriented at high angles to NE orientated fractures.
Determination of Effective Matrix and Fracture Compressibilities from Production Data and Material Balance
Authors: Ham J. M. , Moreno A. , Villasana J. C. , Herrera R. Perez , Rodney C. A. 
Published: September 2015

Abstract
A new method is proposed to estimate the matrix and fracture’s effective compressibilities by using the material balance equation (MBE) and production data. Assuming the behavior of naturally fractured reservoir (NFR), accordingly to the pressure tests analysis, it is then possible to replace the effective compressibilities into a MBE of double porosity to determine original oil from both systems.
Due to the lack of information from cores and the problem that implies acquiring it, this method represents a useful alternative for analytical models. Generally, it is complicated to determine representative values of fracture compressibilities for the entire reservoir; especially when this is very heterogeneous. The calculated compressibility of the matrix and fractures can be compared with formation compressibility correlations when there are no core analysis or pressure tests available.
This is an innovative method to obtain reliable compressibilities for the analysis of material balance of double porosity (MBDP). In addition, with this method it is also possible to obtain the original ratio of the volume stored in the fractures to the total volume in the reservoir; which is a crucial factor in the determination of the final oil recovery.
Strategy for Calibrating a Field-Scale Numerical Simulation Study for the Implementation of a Chemical Enhanced Oil Recovery Pilot Using Core Flooding and Pre-Pilot Experiments
Authors: Bozorgzadeh M. , Stofferis M. M. , Yznaga R. Angulo , Cubillos H. , Caro E. Yuste , Montes J. , Gallego P. Alonso , Rodriguez R. , Fernandez P. Romero , Blin N. , Prieto C. A. 
Published: September 2015

Abstract
Chemical Enhanced Oil Recovery (CEOR) in a multi-layered reservoir environment with moderate to strong natural water-drive is a complex process with associated risks and uncertainties. Reservoir simulation is one of the most important tools available to predict behavior under chemical flooding conditions and to study sensitivities aimed to a cost-effective CEOR process implementation. Key to the success of a reliable reservoir simulation is the application of a de-risking process and the acquisition of important calibration data, such as laboratory core-flood data and field-scale pilot experiments.
A CEOR pilot is currently undertaken in the Caracara Sur (CCS) field (Llanos Basin, Colombia) which has an unfavorable mobility ratio and very low water salinity. However challenges exist, such as strong water drive (no water injection experience), high temperature and a complex geological nature (up to 15 reservoir layers that made up of multiple isolated distributary channels). A detailed reservoir simulation model was built to study full field implementation of CEOR in Caracara Sur. The model was calibrated with laboratory tests data, residual oil saturations from Single Well CEOR ASP Well Tracer Test Pilots, injectivity tests and breakthrough times from inter-well tracer tests.
The paper discusses the approaches taken for full field modeling of Caracara Sur using commercial software and describes how the data collected from alkaline/surfactant/polymer (ASP) core flooding were up scaled and used in pilot sector modeling and for designing tracer back flow tests (TBFT) and single well tracer tests (SWTT) before and after ASP flooding. The TBFT and SWTT results in a pilot injection well, in the middle of three producers, confirmed the absence of aquifer drift, which was also predicted by pilot sector modeling. The paper explains how the obtained results from the tracer tests (residual oil saturations, breakthrough times) and well injectivity were used to calibrate the full field numerical model for reliable prediction of the effectiveness of the ASP flooding.
Modelling Reservoir Depletion Processes to Obtain Representative Oil Formation Volume Factors
Authors: Liu Lulu , Williams John M. 
Published: September 2015

Abstract
This research investigates the way laboratory oil formation volume factors (FVF or Bo) from differential liberation (DL) and flash separation tests are used by engineers to represent real reservoir production processes. A survey about Bo was performed among industry professionals. The work proposes standardisation in these approaches, including a way of adjusting laboratory DL data to represent a true differential process and a new technique for obtaining composite Bo data from combined DL and separator tests. Finally, 3-D reservoir black-oil and compositional models were developed to calculate Bo and explore which phase behaviour processes ECLIPSE 100 and ECLIPSE 300 are mimicking.
This paper shows laboratory Bo data are commonly misunderstood by engineers, and recommends greater awareness and better education. A novel analysis of laboratory DL studies demonstrates that these can seriously overestimate true differential processes. The work tests and discusses the feasibility of using 3D compositional simulation models to derive more realistic Bo values for the combined reservoir and production process. A procedure has been written based on the findings of this work to help petroleum and PVT engineers to standardise the reporting and proper use of laboratory Bo measurements.
Innovative PDC Bit Design Increases Drilling Efficiency in Egypt’s Notoriously Difficult Western Desert Deep Lithology Column
Authors: Farouk H.. , Elwekeel W.. , Shokry A. E. , Ibrahim A.. , Sherif M.. , Elsherif O. H. , Aguib K.. , Bits Smith 
Published: September 2015

Abstract
Efficiently drilling the deep lithology column with PDC bits in Egypt’s Western Desert (WD) has been extremely challenging. The formations—Alam El Buwaib, Masajid, Zahra, and Safa—contain a volatile mixture of highly interbedded sandstone, siltstone, and shale that have damaged PDC bits, especially at depths of 12,500 ft and greater. In addition to the demanding drilling requirements, operators are pursuing multiple targets per well for better cost optimization. Finally, a tight control on target drilling days has required more efficient and consistent drilling solutions. In addition, the array of different drive types and BHAs used in the area have all suffered and exhibited the same symptoms: high stick/slip, high shock and vibration, failure of MLWD tools, RSS, or positive displacement motor (PDM), and premature tripping for bit changeout.
To solve the issues, several 8½-in PDC bits were developed that feature a central conical diamond element (CDE). The bit designs feature an abbreviated cutting structure profile at the bit center that generates a rock column that stabilizes the bit. The rock column is constantly being destroyed with axial force as opposed to traditional shear, resulting in lower torque magnitude and fluctuations. The reduction in torque fluctuations increases the bit’s potential to solve a combination of vibration issues. The new-style bits were scheduled to be field tested in different wells and runs in Egypt’s Western Desert applications, including with classical rotary BHAs, with different RSS/PDM types in a variety of directional well profiles, at different depths, and in different fields. This robust field campaign was performed with the intent of proving and providing a consistent solution and grounds for a paradigm shift of how PDC bits need to be constructed.
The results of the multifield campaign delivered low levels of torque and torque fluctuations; enhanced bit durability, frequently replacing two bits or more; low vibration levels; a significant increase in cuttings size, thereby enhancing surface formation identification; and high dogleg capability and smooth directional response. The bits also increased footage and overall ROP due to preserving the cutting structure, producing a performance step change and achieving consistent lower cost per foot across the WD field.
The field test campaign results in Western Desert spans over 60 runs conducted over a 12-month period. A close monitoring of the performance improvement has been tracked where the runs are rated against offsets. The rating is in terms of overall run performance, footage improvement, ROP increase, cutting structure condition, and overall dull grade. The new bits set over 30 new benchmarks.