bluuebunny/crossref_metadata_2025_split huggingface dataset:
A CO2 Sequestration Simulation Case Study at the Dickman Field, Ness Co., Kansas
Authors: Liner C. L. , Geng P. , Zeng J. , King H. , Li J 
Published: October 2011

Abstract
Since 2006 the University of Houston has evaluated CO2 sequestration potential in a deep saline aquifer system in Ness County, Kansas. This paper is a summary on the simulation part of the project.
Combining 3D seismic and dense well control, a static model was constructed and history matching was accomplished.Good history matching validates the static geological model and the same model can then be further used for CO2 sequestration prediction.
After history matching, several aquifer simulation models were constructed to study the CO2 injection rate and storage safety issues. A full formation simulation model including sallow geological layers and deep saline aquifer was further constructed to predict CO2 migration after injection. Free CO2 gas trapped in a geological structure can migrate to the surface through faults, fractures, failed cap rock, or corroded well pipe. These actions represent a real safety threat. A major challenge is to develop a practical simulation model to study CO2 leakage scenarios over long time periods (typically 250 years in our work). One way of improving CO2 storage safety is to accelerate residual gas and solubility trapping. Our simulation results indicate two effective ways of reducing free CO2: injecting CO2 with brine, and/or horizontal well injection. In the carbonate aquifer we studied, tuned combination of these methods can reduce the amount of free CO2 from over 50% to less than 10%.
As part of the lower Paleozoic aquifer system in Kansas, Missouri and Oklahoma, the site under the Dickman oil field shows potential as a viable CO2 storage site. However, faulting and numerous abandoned wells cast uncertainty on its ability to serve as a permanent CO2 storage site. This study shows that a careful simulation study can maximize CO2 injection rate, minimize existence of free CO2, and significantly reduce uncertainty in the safety of CO2 permanent storage.
Use of Data-Driven and Engineering Modeling to Plan and Evaluate Hydraulic Fracture Stimulated Horizontal Bakken Completions
Authors: Shelley Robert F. , O'Connell Kevin E. , Skari David , Baribault Rey A. 
Published: October 2011

Abstract
Drilling horizontally to facilitate hydraulic fracturing is proving to be the well type of choice to develop the low permeability Bakken Shale in the Williston Basin. However, as the complexity of these completions increases (to 30 or more hydraulic fracturing treatments per well), the challenge of modeling these completions and justifying the expenditure ($3 million or more) is becoming more problematic. In addition, there is frequently only limited reservoir data available due to horizontal open hole logging limitations and the fact that the middle Bakken target zone is rarely completely penetrated. In addition to formation evaluation and rock mechanics, other difficult to access issues such as hydraulic fracture geometry, frac staging methodology, perforation methodology, frac compartment zone isolation, drillout/cleanup, wellbore placement/orientation, etc., can also have a significant effect on well production and economics. This presentation will describe a methodology which is being used to improve hydraulic fracture understanding and facilitate decision making pertaining to the completion and stimulation of horizontal Bakken wells. Case histories from the Truax and Wildrose areas in Williams and Divide Counties, North Dakota are used to demonstrate the usefulness of using this type of approach.
Long Term Hydrocarbon Removal Using Treatment Wetlands
Authors: Wallace Scott , Schmidt Martin , Larson Eric 
Published: October 2011

Abstract
This study focuses on the treatment performance of two full-scale treatment wetlands constructed by BP for groundwater remediation. The first is in Casper, Wyoming (commissioned in 2003); the second is located in Wellsville, New York (commissioned in 2008). Treatment wetlands were selected in both cases due to low operating costs, which result in favorable life-cycle costs when managing legacy contaminants associated with former refining operations.
Both treatment systems have been highly effective and have met regulatory compliance objectives. System performance can be measured by a first-order, area-based rate coefficient (k), that can be applied to future wetland design projects. For the full-scale Casper wetland, rate coefficients were measured as 0.66, 0.96, and 0.89 m/d for benzene, BTEX and gasoline-range organics, respectively. The wetland system removes essentially 100% of these constituents, with non-detect concentrations in the effluent.
For the full-scale Wellsville wetland, rate coefficients were measured as 0.37 and 0.33 m/d for aniline and nitrobenzene. The wetland system has removed 94% of the aniline and 93% of the nitrobenzene (based on mean influent and effluent concentration values over the period of record). Treatment performance has been very stable after the initial winter start-up period. Excursions above non-detect concentrations typically occur during the winter months when water temperatures are at a minimum and the wetlands are partially iced over. The Wellsville system has also been very effective in iron removal, removing 98% of the iron (based on mean concentration values), despite relatively high influent concentrations (mean value of 33.3 mg/L).
Both systems operate under cold climate conditions. The Casper wetland operates at temperatures as low as -35°C; the Wellsville wetland operates at temperatures that can drop below -20°C. The multi-year performance history of these two wetland systems demonstrates that wetlands are a viable and cost-effective treatment alternative, even under cold climate conditions.
Three- Phase Unsteady-State Relative Permeability Measurements in Consolidated Cores Using Three Immisicible Liquids
Authors: Cao P. , Siddiqui S. 
Published: October 2011

Abstract
This paper discusses results from a series of two- and three-phase coreflooding experiments on consolidated cores using three immiscible fluids and using an unsteady-state relative permeability setup. The three-phase extension of the Buckley-Leverett theory proposed by Grader and O’Meara (1988) and verified by Siddiqui et al. (1996) was used for calculating three-phase relative permeabilities from the dynamic displacement data. From the results of three-phase displacement experiment, three-phase saturation trajectories are mapped and then compared against results of DDI (decreasing of water phase and oil or heavy phase and increasing of gas or light phase during a dynamic injection stage) runs found in the literature. The DID (decreasing of water phase, increasing of oil or heavy phase and decreasing of gas or light phase) runs presented in the current work are unique which map a wide range of the interior region of the ternary diagram. However, bypassing was observed during the IDD (Increasing of water phase and decreasing of oil or heavy phase and gas or light phase) runs, possibly due to fluids reaching the residual saturations before the dynamic water injection. In the petroleum industry, empirical models are often used to extrapolate three-phase relative permeabilities from two sets of two-phase relative permeability data. The experimental three-phase relative permeability data from the DDI and DID runs are compared with the model data, and it is found out that in some cases these models cannot adequately provide satisfactory matches with the experimental data.
A New Compact Triaxial Perforation Tunnel Stability Tester
Authors: Saito Yuya , Sato Hirotaka , Morita Nobuo 
Published: October 2011

Abstract
Thick wall cylinder testers (TWC testers) are commonly used for evaluating perforation stability. However, the results are ambiguous since the standard TWC testers use cylindrical cores where only uniform confining pressure can be applied, while the real in-situ stress is directional around perforations. A new triaxial perforation tunnel stability tester (TPS tester) is developed to simulate perforation stability under more realistic conditions. Normally, it requires a relatively large pressure cell and three independent pressure pumps to create a triaxial stress state in a cubic sample. However, the equipment developed in this paper is as simple and as small as the standard TWC testers with the following configurations:
Sample is a cubic rock with a 0.5 inch hole as the standard TWC test. The dimension of the cubic sample is 1.5 in. × 1.5 in. and the thickness is adjusted by core availability (normally varies from 0.75 in. to 1.5 in.). The stress ratio of the horizontal to vertical stresses in perpendicular to the hole axis can be varied between 0.33 to 1.0. The pressurization system requires only one pump by increasing the two confining stresses proportionally. A square jacket has a device to induce the directional loading. The pressure cell is as small as the standard TWC tester and the test procedure is also as simple as the standard TWC test.
Using the above device, various rock samples are tested varying the ratio of horizontal and vertical stresses. The results show that unlike the standard TWC tests, the perforation stability tests with the same in-situ stress ratio as the field one do not require corrections of directional in-situ stress effect. Note that depending on rock non-linearity, complex correction factors from hydrostatic confining stress to directional stress is required for the standard TWC tests since pre-mature failures are commonly observed for hydrostatic loading. The equipment is handy and portable so that it can be used in a small field laboratory.
Structural and Stratigraphic Control on the Trapping Machanism in Stacked Reservoirs of Kuwait
Authors: Azim Shaikh Abdul , Al-Otaibi Basel , Al-Qattan Sarah , Al-Saad Bader 
Published: October 2011

Abstract
Two giant faulted domal structures are separated by a narrow saddle on the northern extension of Burgan Arch in Kuwait. The structures hold oil at multiple levels in Zubair, Burgan, Mauddud and Tuba Formations with varying entrapment mechanisms. The Zubair Formation is a major oil reservoir in Eastern structure but water wet in the structurally higher Western structure while the Tuba Formation is oil bearing only in the West and wet in East.
Multiple phases of oil migration, filling, up-fault migration and spilling of the traps due to tilting and faulting have been postulated from an integrated study of geochemistry, trapping mechanism and structural history. The early charge of immature and bio degraded oils have been replaced by more mature lighter oil. Part of the spilling and redistribution of oil is due to the structural tilting initiated during the Zagros orogeny. Deeper relict oil, geometry of a heavy-oil wedge, presence of higher porosity in carbonates, residual oil rims below the original oil water contacts indicate structural tilt towards the north and west. Another interesting feature is the presence of high asphaltene oil in the form of a massive "mushroom" plug in the central part surrounded by lighter oil in and Burgan formation of western structure. The immovable oil and nearby lighter oil at same depths have similar biomarkers indicating a common source but different spill/charge histories. The lighter hydrocarbons have moved up through faults in the crestal area leaving behind the asphaltene rich heavy oil. In Eastern structure, the major part of Zubair is devoid of movable hydrocarbons in structural traps due to up-fault migration, lesser charge and inefficient seal of cavernous Shuaiba limestone. In contrast, giant structural oil traps in Western structure are to due to the smaller oil leakage along the less intense faults and more charging from the southwest. Additional support to the migration theory is that all the overlying traps are filled to spill point other than Zubair. Hydrocarbons are trapped in Burgan and Mauddud due to seals provided by carbonate cemented sands of Middle Burgan and marine shales of Wara.
Understanding the redistribution of oil in structural traps and the basinal oil charging have been pursued in discovery and delineation of the stratigraphic traps of Zubair and Ratawi Formations of the Eastern structure. These traps are much smaller compared to the giant structural traps.
Predicting Shale Reservoir Response to Stimulation in the Upper Devonian of West Virginia
Authors: Moos Daniel , Vassilellis G. , Cade R. , Franquet J. , Lacazette A. , Bourtembourg E. , Daniel G. 
Published: October 2011

Abstract
A comprehensive site study carried out in an Upper Devonian shale gas reservoir at a site in southern West Virginia provided data to test a geomechanical model for stimulation of the Huron formation. Using a model in which natural fractures provide the primary conduits for production and are the major target for stimulation, and in which stimulation triggers shear slip on those pre-existing fractures, we were able to predict the shape of the reservoir volume stimulated by injection of high-quality foam and to match injection flow rates and pressures using a dual porosity dual permeability finite-difference flow simulator with anisotropic, pressure-sensitive reservoir properties. The resulting calibrated model matched both the relative contribution of the individual stages measured by production logging and the early-life well production. This suggests that similar models may in the future provide earlier and better production predictions, guidance for completion and stimulation design, and recommendations to minimize production decline and maximize well value.
Drill Pipe Dynamic Measurements Provide Valuable Insight Into Drill String Dysfunctions
Authors: Raap Constantijn , Craig Andrew D. , Graham Ryan 
Published: October 2011

Abstract
Recently the oil and gas drilling industry has become increasingly interested in drilling dynamics and vibration as a cause of reduced drilling performance, downhole tool and drill string failures. Historically, vibration data has been captured by an MWD tool incorporated in the lower BHA. Whilst this provides valuable information on the dynamic behaviour of the lower BHA, this approach is not always sufficient for understanding the drill string dynamics of more complex applications. Two case wells are discussed within this paper in which high frequency vibration data was recorded at several strategic and innovative points within the drill string. The acquisition and analysis of this data provided new insights of the dynamic behaviour of drill strings in high angle wells.
A large international operator experienced both excessive and erratic surface torque during the first horizontal section of a large development project. The available surface drilling parameters and MWD vibration data were analysed, but the cause for the excessive surface torque could not be explained. To gain an understanding of the dynamic conditions across the drill string and to help identify the cause for the excessive torque, multiple Downhole Dynamics Recorders (DDRs) were included in the drill pipe, at positions up to 2500 metres from the drill bit, for two subsequent wells.
The DDR data revealed that during periods of excessive surface torque, severe levels of sustained lateral vibration were present in the drill pipe, but not in the lower BHA, where traditional vibration measurement tools are located. Two drill string failures occurred during the second well and the fracture profile suggested that they were the result of fatigue failure. The DDR tools located in close proximity to the failure points recorded periods of severe and sustained lateral vibration. It is likely that fatigue failure of the drill string was accelerated by the high and cyclic bending stresses generated during these periods of vibration.
In conclusion, dynamic dysfunctions can be present at any point in the drill string and these dysfunctions can have severe consequences within a short period of time. Furthermore, it is shown that novel and untraditional downhole measurements are required to understand, and mitigate, these dynamic dysfunctions.
Hydraulic Fracture-Height Growth: Real Data
Authors: Fisher Kevin , Warpinski Norm 
Published: October 2011

Abstract
Much public discourse has taken place regarding hydraulic-fracture growth in unconventional reservoirs and whether fractures could potentially grow up to the surface and create communication pathways for frac fluids or produced hydrocarbons to pollute groundwater supplies. Real fracture-growth data mapped during thousands of fracturing treatments in unconventional reservoirs are presented along with the reported aquifer depths in the vicinity of the fractured wells. These data are supplemented with an in-depth discussion of fracture-growth limiting mechanisms augmented by mineback tests and other studies performed to visually examine hydraulic fractures. These height-growth limiting mechanisms, which are supported by the mapping data, provide insight into why hydraulic fractures are longer laterally and more constrained vertically. This information can be used to improve models, optimize fracturing, and provide definitive data for regulators and interest groups.
Performance Advance in Section Milling Technology
Authors: Stowe Cal , Ponder Andrew 
Published: October 2011

Summary
Tungsten carbide cutter technology is over 50 years old, yet much of its potential for milling steel downhole was only recently realized with enhancements to the cutter design and the material composition. Substantial performance improvement was achieved by carefully tailoring the cutter geometry and carbide chemistry to the downhole environment.
This new technology was used to meet a North Sea customer's call for improved section milling performance. The goal was to reduce the number of days to plug and abandon a well for platform slot recovery. The results were remarkable, with an average of five days saved per well, which represented approx. US$3 million in savings for the operator. This was accomplished by reducing the number of milling trips from three to one. Ten wells have been milled to date, with uniformly good results.
In section milling, the mill is run to the desired depth and cutting knives are extended to cut through the casing wall. After cutting through, the knives mill down to remove the unwanted casing. The mill was run in conjunction with a downhole monitoring tool to obtain real time data during the case studies. This data helped optimize operating parameters to minimize downhole vibration.
The new cutting insert has significant advantages over a conventional insert. The new carbide chemistry provides both impact and wear resistance, and the new geometry reduces rubbing area for faster cutting. The edge design is both sharp and impact resistant, and features an effective chip breaker to reduce cuttings packoff while milling.
Recent implementation of the new technology, its successful outcome, and lessons learned from its use in offshore plug and abandonment will be included for review and discussion.
Formalization and Standardization of the Smart Well Modeling Workflow
Authors: Hudson John D. , Alves Ibere , Khoshkbarchi Mohammad 
Published: October 2011

Abstract
Case studies and related to approximately 30 oil and gas production fields containing smart wells were reviewed to consider the work process that was used to justify the incremental investment in hardware and installation cost. These fields are from two operating companies and are distributed across most major oil and gas productive regions worldwide. The paper outlines key findings from the review, recommends a project-stage-based modelling workflow and presents opportunities for improvements to support more rigorous and efficient design decisions.
Challenges and Surprises of Abnormal Pore Pressures in Shale Gas Formations
Authors: Zhang Jincai , Wieseneck James 
Published: October 2011

Abstract
Drilling the gas-bearing shales in the Bossier and Haynesville formations in northwestern Louisiana presents many drilling challenges. Pore pressures increase from slightly elevated levels to a surprisingly high geopressures over short intervals. These pressures, if not correctly predicted, can lead to dangerous gas kicks and potentially blowouts. In the shale gas formations, conventional log-based pore pressure prediction techniques did not work well. The presence of gas in the shales adversely affected the compressional velocity. The impact of the Sabine uplift also reduced the ability of conventional pore pressure techniques to quantify pressures adequately in the objective formations. Instead we analyzed 54 kicks and other downhole measurements across the field to analyze the abnormal pressures. This approach yielded consistent results and provided a reliable basis for pore pressure prediction. The pore pressures in the lower Bossier and Haynesville shale gas formations show highly overpressured after a overpressure transition in upper Bossier shales, and unloading effect on pore pressure in those formation are also identified. Using the kick derived pore pressure model and improved log-based effective stress models, we developed a comprehensive pore pressure prediction method.
Drilling with a Balanced-Activity Invert Emulsion Fluid in Shale: Is It Sufficient for Maintaining or Enhancing Wellbore Stability?
Authors: Hemphill Terry 
Published: October 2011

Abstract
The great majority of wellbore stability problems encountered while drilling occur in shale formations. As invert emulsion drilling fluids (IEF) are commonly used to drill reactive shales in today's challenging wells, better understanding is needed of shale failure with exposure to IEF. Over the years, the concept of shale stability and interaction with IEF has been linked to several theories:
Semi-permeable membrane theory Osmotic pressure theory Balanced activity theory
Understanding of these individual theories is helpful to interpreting experimental data presented in this paper.
The shale that is the subject of this study was cored from deepwater operations, offshore West Africa. The operator who supplied the core had previously tested core samples in air, in water, and in a triaxial test apparatus. The results from the tests are reported here. Later, experimental testing of the deepwater shale was performed with a new test apparatus that has been presented to the industry. In short, this new appartus allows for shale samples to be directly tested under downhole conditions, and results have been shared with the drilling industry. Analysis of the test results in light of "balanced activity" theory calls this theory into question. The results show that even at an activity level higher than the known shale activity level, water was able to enter the shale and weaken it. This paper uses the concept of "chemomechanical balance" to explain measured results in terms of the coupling of shale mechanical properties and IEF chemical activity and the resulting consequences for selection of activity levels for IEF.