bluuebunny/crossref_metadata_2025_split huggingface dataset:
Minimizing Over-Flush Volumes at the End of Fracture-Stimulation Stages - An Eagle Ford Case Study
Authors: Al-Tailji Wadhah , Northington Neill , Conway Matthew , Davidson Brian 
Published: October 2014

Abstract
With the growing popularity of multi-stage hydraulic fracturing treatments in horizontal wellbores, various completion systems have been utilized for mechanical isolation and staging of individual fracture treatments. One of the more popular fracture staging techniques is the plug-and-perf technique in cemented casing, which requires the lateral section of the wellbore to be free of debris and proppant so that the plug and perforation tool string can be pumped down to the desired setting depth. Proppant that has settled in the lateral can result in plugs getting stuck and prematurely setting at the wrong depth, requiring costly intervention work and delaying the progress of completing the well.
The industry standard practice to prepare a clean wellbore has been to over-flush each fracture treatment by 50 to 100 barrels in excess of the volume to the perforations. This practice has raised concerns about disturbing near-wellbore proppant conductivity and potentially harming fracture continuity with the wellbore, and thus productivity. Since operators have achieved satisfactory economics in many shale plays, this practice continues despite its controversy.
These concerns have led to experiments in minimizing excess flush volumes in wells located in the liquids-bearing window of the Eagle Ford Shale. This paper proposes a process involving the use of real-time treatment data displayed within a wellbore model simulation to adjust the flush volume of each stage based on the reduction in proppant concentration at the perforations. Over 200 stages were successfully placed with this method with no incidences of plugs sticking in the lateral. This paper contains a selection of treatment charts and wellbore diagrams from actual applications of this method. Simulated fracture profiles of different over-flush scenarios are also compared and discussed.
This paper will be useful for engineers and managers involved in well completions and stimulation, and presents detailed methodology for successfully applying this strategy in their fields. By applying these procedures, continuity between the proppant pack in the fractures and the wellbore should be improved, and fresh water usage will be reduced.
Simultaneous Operations in Multi-Well Pad: a Cost Effective way of Drilling Multi Wells Pad and Deliver 8 Fracs a Day
Authors: Ogoke V. C. , Schauerte L. J. , Bouchard G. , Inglehart S. C. 
Published: October 2014

Abstract
Unconventional gas or tight shale-oil plays require a high density of wells and multistage hydraulic fracturing to economically develop. This leads to the use of high density well pads to reduce land costs, associated environmental impact and well delivery efficiency through batch drilling. A pad in Shell's North American assets of Groundbirch and Fox Creek (Canada), Appalachia, Permian and Eagleford (USA) can comprise of two opposing rows of 13 - 20 horizontal wells spaced three to six meters apart.
Considering it takes an average of 14 days to drill a 5,000m well and a subsequent nine days to complete the multistage hydraulic fracturing sequence, a typical 26 well pad in the Grounbirch asset would take approximately two years from spud to first gas.
Simultaneous Operations (SIMOPS) is defined as when two or more mutually exclusive activities take place within 50m of a wellbore, or each other. The activities are classified as critical and have to be carefully planned to ensure the safety of all personnel involved and comply with regulatory spacing stipulations. This paper aims to illustrate how Shell Canada implemented SIMOPS; further highlighting how rig operations were successfully co-ordinated during a restrictive weather period (melting snow and associated road bans) and how simultaneous completion operations were utilized to achieve eight hydraulic fracturing jobs, or ‘fracs’, a day, averaging 6.2 fracs/day over 13 wells.
Maximizing Capital Efficiency by Expanding the Limiter Redesign Process to Flat Time Operations
Authors: Valenta M. A. , Walker M. W. , Pastusek P. E. , Bailey J. R. , Elks W. C. , Lewis S. B. , Mitchell N. D. 
Published: October 2014

Abstract
The operator's drilling efficiency program has been expanded to a Limiter Redesign Process that seeks to optimize all rig time, including flat time. As drilling efficiency gains have been achieved, flat time now accounts for roughly 80% of the total rig time and approximately 70% of the total cost of drilling and completions operations; leaving 20% of rig time for drilling. This fact led to the generation of a comprehensive Flat Time Reduction (FTR) program.
The Fast Drill Process has become a well-known workflow to identify hole-making limiters and mitigate them through "relentless redesign to the economic limit of performance". Efforts to increase drilling efficiency continue, and this process has yielded a continuous increase in the overall footage per day and a reduction in flat time within individual hole sections.
To address operations that do not include drilling of rock, the operator has launched a similar effort and workflow process which focuses on "flat time" portions of the well construction process. This has become a key focal point in the organizations approach to maximize capital efficiency. The Flat Time Reduction process provides an environment in which operations are optimized while further enhancing a workplace where "Nobody Gets Hurt."
This process is yielding significant savings globally and has been accomplished through planning, "real-time" recognition and response, collaboration with service providers, and a focus on Non-Productive Time (NPT) reduction while continuously improving safety performance. Field applications of limiter redesign are discussed in this paper. The purpose of this paper is to present the current status and specific approaches being used to reduce flat time and share the workflow process.
Digital Rocks: Developing an Emerging Technology Through to a Proven Capability Deployed in the Business
Authors: Fredrich J. T. , Lakshtanov D. L. , Lane N. M. , Liu E. B. , Natarajan C. S. , Ni D. M. , Toms J. J. 
Published: October 2014

Abstract
This paper describes the development of ‘Digital Rocks’ technology – in which high-resolution 3D image data is used in conjunction with advanced modeling and simulation methods to "measure" petrophysical rock properties – through to a proven capability that is sanctioned for use in the operating assets of a large, multinational oil company. Digital Rocks is a disruptive technology in that it can fundamentally alter how the industry measures the basic rock properties that are used to characterize reservoirs and help predict their performance. Whilst Digital Rocks has been the subject of a number of publications, these have been generally limited in scope, and focus on certain aspects of the underlying science, or alternatively, present a stand-alone example application. This paper describes the research and development process, summarizes the results of extensive field trials, and explains how application of this technology has produced value within the context of an established field development decision-making process.
We describe the underlying philosophy motivating the specific research that has been undertaken, and more generally, the technology development process that included extensive verification and validation. The paper describes navigating through the ‘valley of death’ – which describes the intervening terrain between research & development and the industrial application of a proven technology – a key challenge for nearly all emerging technologies. Details of the required capabilities, including experimental x-ray micro-computed tomographic imaging, image processing, numerical simulation including high performance computing, and rock physics interpretation are described.
The technology development described is specific to static rock properties, and its application to conventional oil and gas reservoirs (i.e. permeabilities of ~1 millidarcy or greater). The results of over a half-dozen field trials carried out across BP's portfolio are presented, including comparisons of image-based porosity and simulated permeability, formation factor, cementation exponent, resistivity index, saturation exponent, and capillary pressure with experimental data that have been obtained using traditional laboratory measurement techniques on core plugs. The field trials included over 100 plugs taken from cores from more than ten wells.
Digital Rocks technology can improve evaluation of reservoir quality and quantification of hydrocarbons in place, and it can help inform the development of improved recovery methods. Key advantages include reducing the cycle time for appraisal and reducing uncertainty in subsurface description.
Use of a Non-Invasive, Non-Damaging Blocking Agent for Improved Cleaning in Low Bottomhole Pressure Wells
Authors: Ananaba O. Victor , Hain Larry L. , White Jason A. , Craig Steven H. , Koch Richard T. 
Published: October 2014

Abstract
Solids removal from severely depleted wells remains a challenging intervention operation in the oil and gas industry. The various cleanout options that exist generally require significant expense, and may result in loss of potentially damaging fluids or permeability reduction to zones with low bottomhole pressures.
This paper will focus on several field trials in South Texas utilizing a fluid-based, formation-blocking agent as part of the cleanout circulating fluid. The blocking agent has been in use for several years in cement spacer systems as a lost circulation material (LCM) with favorable results. The blocking agent uses a modified, hydrophobic polysaccharide to form micelles. Under differential pressure the micelles adsorb and realign in a layer along the formation or perforation tunnel forming an impermeable seal effectively blocking the loss of fluids to the formation. With the formation blocked, the solids can be circulated out using a higher density fluid and at higher circulation rates than the low-pressure reservoir would support. When the well is returned to an underbalanced system, the micelles will disperse, returning the fluid to its original state and restoring permeability to near a pre-intervention level.
The case histories included in this paper are the first application of this material for well intervention operations outside a cement spacer application, and the results discussed show that the material performed remarkably well.
From Regional Depositional Architecture to Reservoir-Scale Considerations, Lower Paleozoic Baltic Basin, N Poland
Authors: Krzywiec P. , Volterrani S. , Slonka L. , Lis P. , Buffenmyer V. , Malinowski M. , Lewandowski M. 
Published: October 2014

Abstract
The western edge of the East European Craton in Poland has recently been the focus of intense exploration efforts for unconventional hydrocarbons, led by Polish and foreign companies. Results of early exploration wells clearly demonstrate that there are still many unknowns regarding various aspects of the unconventional petroleum system, both regional (structure and depositional architecture of the Lower Paleozoic succession) and more local (variations of shale thickness, TOC, mechanical properties etc.). In order to shed light on some of these problems high-effort regional reflection seismic survey PolandSPAN has been acquired that covered entire Lower Paleozoic basin developed above the SW edge of the East European Craton. Following regional interpretation a feasibility study devoted to seismic reservoir characterization has been completed that allowed to assess applicability of seismic reflection data for reservoir-oriented studies of the Lower Paleozoic shales in Poland.
The Lower Paleozoic basin in Poland is located above the southwest edge of the East European Craton, northwest from the Teisseyre – Tornquist Zone which is separating the cratonic plate from the West European Platform (Ziegler, 1992; Doornenbal & Stevenson, 2010). Later Late Paleozoic tectonic movements resulted in compartmentalization of the Lower Paleozoic basin into three sub-basins: Baltic Basin, Podlasie Basin and Lublin Basin (Fig. 1). During the Precambrian/Cambrian, the cratonic edge underwent extension and rifting of the Rodinia supercontinent, while Cambrian – Middle Ordovician subsidence was driven by a post-rift lithospheric thermal cooling (Poprawa et al., 1999; Poprawa, 2006a). In the Late Ordovician – Silurian, the cratonic edge was under the strong influence of the Caledonian thrust belt, and was incorporated into its flexural foredeep basin (Poprawa et al., 1999; Nawrocki & Poprawa, 2006). Deposition was dominated by fine-grained organic rich shales, generally derived from the eroded orogenic wedge and deposited in the distal foredeep basin (Poprawa et al., 1999; Poprawa, 2006b). The Silurian Caledonian foredeep basin encompassed vast areas stretching from the present-day Sweden across Estonia, Latvian, Lithuania, Russia (i.e. Kaliningrad District), Poland, Belarus, Ukraine and farther to the southeast (Poprawa et al., 1999; Skompski et al., 2008; Zdanaviciute and Lazauskiene, 2007). Presently available information regarding the Caledonian orogenic wedge is very limited and mostly indirect, based on e.g. provenance studies of the foredeep infill, as it was destroyed and deeply buried during the later tectonic phases (Poprawa, 2006b).
Structural Uncertainty Integration within Reservoir Risk Analysis and History Matching
Authors: Sabatino R. , Viviani E. , Della Rossa E. , Sala C. , Maffioli A. 
Published: October 2014

Abstract
Reservoir structural modelling is one of the fundamental steps in a reservoir study workflow. The impact of the structural uncertainties on the dynamic response of the reservoir is well known and not negligible, but often the reservoir shape is considered as fixed due to the complexity to manage alternative geological structures in multi-realisations simulation loop. Nevertheless, both Risk Analysis (RA) and History Matching (HM) workflows strongly require a practical and time-effective methodology for structure management with an efficient uncertain geometry parameterization. In this work, an innovative methodology for structural uncertainty handling is presented. The methodology is based on the combination of Principal Component Analysis (PCA) and Elastic Gridding. In particular, the PCA-based parameterization is able to efficiently handle the geophysical uncertainty model, consistent with the geostatistical characterization as well. Such methodology has been structured in an internally developed tool. This tool is specifically designed for a direct handling of corner point geometry grids and allows changes of surfaces, shape and size of internal reservoir layers, fault throw and fault position and even new fault placement, honouring geological constraints. One of the key points of the proposed methodology is the integration of a geologically-oriented parameterization and a statistical parameters reduction technique (the above mentioned PCA) in a workflow which includes commercial HM/RA tool and a dynamic simulator. The result is an efficient structural uncertainty management framework suitable for Risk Analysis and History Matching studies. Among the field applications performed so far, two cases have been chosen aiming at showing the potentialities of the proposed approach. The first example is a history matching exercise on an undersatured oil reservoir. A comparison between the traditional and the "structural", even if simplified, HM is herein provided, showing the improvement due to a better geologically-oriented uncertainty model. The second example is a risk analysis application on an oil field, with a strong uncertainty of the oil in place due to lack of accurate knowledge of the reservoir flanks shape. The application highlights the advantages deriving from the geophysical PCA-based workflow.
Fault Diagnosis in Oil Wells
Authors: Horowitz G. , Faundez E. , Maestri M. , Cassanello M. 
Published: October 2014

Abstract
A new automatic fault diagnostic method based on variable trend analysis was developed. Every time a fault is detected, the proposed method uses a local model to determine the variable trends associated to the detected fault. The fault identification is achieved by comparing the extracted variable trends with a previously generated library of faults signatures. The method was implemented and tested with a set of faults purposedly generated in an oil production well equipped with a pressure cavity pump (PCP). It was able to correctly identify all the generated faults, outperforming simpler versions of the method based on global models.
First Successful Application of Horizontal Open Hole Multistage Completion Systems in Turkey's Selmo Field
Authors: Mitchell David , Davis Justin , Appleton Joel , Watson Mark 
Published: October 2014

Abstract
Turkey has significant oil and gas reserves that have not been fully developed. This paper will highlight the planning, execution, challenges and production benefits of the first installations of horizontal open hole multistage completion systems in the Şelmo field. Located in southeastern Turkey and north of the prolific Zagros fold belt, which encompasses the oil fields of Iran and Iraq, Şelmo is the second largest oil field in Turkey by cumulative production, with an estimated 600 MMbbl of oil in place. An operator has recently started redeveloping the field targeting the Middle Sinan Dolomite zone by drilling horizontal wells.
Matrix acidizing is a method of stimulating carbonate reservoirs for oil and gas production. The acid treatment creates conductive flow channels which transport reservoir fluids from within the formation matrix directly into the wellbore. In matrix acidizing of carbonate reservoirs, accurate acid placement is a major challenge because the acid tends to flow preferentially toward the highest permeability areas. This can result in overstimulation at these intervals leaving the lower permeability regions untreated. A significant percentage of matrix acidizing treatments do not meet expectations because of improper job design. In some cases, increased water production is observed due to preferential stimulation of high permeability sections associated with water. This paper will provide an in depth understanding of acid stimulation of carbonate formations with both single and limited entry open hole multistage systems that can be applied to carbonate reservoirs worldwide.
The operator designed a pilot project including four horizontal wells in the Şelmo field; two wells were completed using single entry open hole multistage completion systems and the other two using batch stimulated limited entry open hole multistage completion systems. In the single entry systems, there is only one injection port per stage while in the limited entry systems, multiple injection jets are used. The jets enable controlled injection and leak off for effective flow of acid into the entire section of the interval. The designed treatment is thereby placed at an optimal rate and pressure along the stage length, maximizing the development of conductive channels throughout the entire stimulated reservoir. Results of the pilot indicate a successful stimulation and a significant increase in production from all four horizontal wells compared to offset vertical wells.
With the success achieved from the first horizontal open hole multistage completion systems in Turkey's Şelmo field, the operator plans to complete more wells using these systems to exploit its assets. The success of this project demonstrates the applicability and benefits of using open hole systems for effective matrix acidizing of carbonate reservoirs around the world.
The Relationship Between Rock Properties and Fracture Conductivity in the Fayetteville Shale
Authors: Briggs Kathryn , Hill A. Daniel , Zhu Ding , Olson Karen 
Published: October 2014

Abstract
Fracture conductivity in shale is largely dependent upon the shale rock properties and the formation conditions. This paper aims to explore two different vertical intervals of the Fayetteville Shale, FL2 and FL3, by comparing laboratory fracture conductivity measurements. Fayetteville Shale outcrop cores were artificially fractured, preserving the surface roughness for the conductivity measurements. Controllable parameters, such as proppant size, concentration and type, were kept consistent between the two zones. An initial unpropped experiment was run, followed by two 30:70 mesh propped experiments at 0.03 lb/ft2 and 0.1 lb/ft2 concentrations.
The FL2 consistently recorded higher conductivity values than the FL3 at closure stress up to 3, 000 psi. Therefore, each zone was evaluated using mineralogical composition, thin-section analysis and surface-roughness scans to identify rock property differences. The FL2 and FL3 rock analysis identified that the two zones are very different. Although the FL2 and FL3 samples used in the conductivity experiments had similar clay content, the FL2 contained more quartz and the FL3 contained more carbonate. Additionally, the FL2 samples were less fissile and had larger surface fragments break along the fracture surface, whereas the FL3 samples broke parallel to the bedding plane and had flaky dust fragments break along the fracture surface. The FL2 had higher conductivity values at low closure stress due to the rearrangement of bulky surface fragments and larger voids created on the surface when fragments were lost. The difference between the FL2 and FL3 conductivity decreases as the concentration of proppant increases because the voids causing unpropped conductivity differences become filled with proppant. Finally, production data was used to confirm laboratory results by providing evidence that wells in the FL3 produce less than the wells in the FL2 formation.
Case study demonstrates "Learning Through Observations" as an effective education tool
Authors: Aggour Mohamed , Hussien Hassan , Fraim Michael 
Published: October 2014

Abstract
Experience has shown that traditional teaching through lecturing generally results in students acquiring/remembering less than 50% of the information delivered in the lecture. Several factors contribute to such ineffective teaching/learning method. Most important among these factor is that information are merely presented at lectures as facts or finding and students are j ust spoon-fed the information. Other contributing factors are the lack of student attention in class, and the fact that students did not spend any effort to acquire the information or knowledge. We believe that students will better remember information/knowledge which they spend effort to acquire or find. Certainly, knowledge acquired as conclusions from observations would never be forgotten. Therefore, we conducted two case studies where students, for each case, were divided into two groups of equal academic strength. One group went through traditional lecturing of course materials of a specific topic, while the other was directed to conduct specific experiments under specific conditions and was asked to arrive at conclusions based on the observations. The two groups for each case study were tested under same conditions and results were compared to determine the effectiveness of the proposed teaching method, which we call "Learning Through Observations (LTO)". The study involved specific topics in two courses. We selected gas lift in the production engineering course, and cementing in the drilling engineering course. The results showed that LTO is a much more effective teaching approach. This paper presents the details of the case study.