bluuebunny/crossref_metadata_2025_split huggingface dataset:
Practical and Operational Use of Assisted History Matching and Model-Based Optimisation in the Salym Field
Authors: Joosten Gerard , Altintas Asli , De Sousa Paulino 
Published: October 2011

Abstract
History matching and future production optimisation in reservoir modelling is being done more and more with the help of automated or assisted computing techniques, such as design of experiments, Ensemble Kalman Filtering or adjoint- and other gradient-based techniques. With the advent of these techniques, reservoir engineers also get less trivial applications of computer assisted optimisation at their disposal. In this paper we will present two such non-trivial applications.
In the first example we demonstrate how an adjoint-based history match, updating gridblock by gridblock permeability, can flag the problematic areas of a model. The results show that good data matches, requiring unrealistic values for updated parameters are not necessarily useless, but can actually provide a lot of information about unmodelled aspects of reservoir behaviour. Some of the learnings from such an exercise are of geological, others of operational nature. In the second example we use, again adjoint-based, gradients of net present value (NPV) with respect to production and injection rates to optimise well work-over timing. In the field under investigation, each injector well starts its life as a producer, for both geomechanical and operational reasons. Making use of the gradients of NPV with respect to the modelled production rate before the conversion and the modelled injection rate after conversion, the process of shifting the conversion moment forward or backward in time has been automated.
The first example allows for the creation of multiple history matched models, by updating static and dynamic models in parallel, while ensuring the geological concepts are maintained. The second example, well conversion moment optimisation, has been used to validate schedules for operational hoist allocation.
Both applications have had a significant impact on the view of the asset team on the practical usage of modelling: in the first one, a very useful multi-disciplinary platform to help steer thoughts on model improvement was found, while the second helped assess the overall impact of operational decisions on field development.
Lean Synchronization for Turnaround Reduction in Seismic Exploration Programs: The Case of Diaba 3D 6000 km2 Deep Offshore Seismic
Authors: Wabara Kingsley , Petton Ronan , Houllevigue Henri , Garinet Emmanuelle 
Published: October 2011

Abstract
The time, from petroleum exploration work program start dates to the drilling of the first exploration well, constitutes an important constraint on the numerous projects performed during this initial exploration period. Schedule extensions may be negotiated when the going gets tough; but, over the long term, delays in delivering work programs as per initial schedule ultimately imply substantial costs in both cash and reputation; the latter usually in the form of increasing negative perceptions of the enterprise capability to perform. To adapt, industry stakeholders have, in turn, been leveraging principles-guided approaches to cut down on their overall program turnarounds. Lean synchronization, the aim of delivering agreed work programs according to pre-defined quality requirements just-in-time (JIT), and at the lowest possible cost, is one of several means to this end. Using the Diaba 6000 km2 3D full Kirchhoff Pre-Stack Time Migration (PSTM) project as a case study, and within the framework of fixed price plus incentive fee (FPIF) contracts, we conceptualized and implemented a new enterprise project management mechanism principally aligned with the key decision logic for lean synchronization. The results, in all project dimensions, were encouraging: over 50% reduction (from 24 to 9 months) of the pre-bid project execution cycle time; "project-delivery" significantly under budget; and substantial improvements relative to the benchmark product quality.
Decoupling the Mechanisms of Microbial Enhanced Oil Recovery
Authors: Armstrong Ryan T. , Wildenschild Dorthe 
Published: October 2011

Abstract
Microbial Enhanced Oil Recovery (MEOR) is a process where microorganisms are used for tertiary oil recovery. Numerous mechanisms have been proposed in the literature through which microorganisms facilitate the mobilization of residual oil. Herein, we focus on the MEOR mechanisms of interfacial tension reduction (via biosurfactant) and bioclogging in water-wet micromodels, using Shewanella oneidensis (MR-1) that causes bioclogging and Bacillus mojavensis (JF-2) that produces biosurfactant and causes bioclogging. Micromodels were flooded with an assortment of flooding solutions ranging from metabolically active bacteria to nutrient limited bacteria to dead inactive biomass to asses the effectiveness of the proposed MEOR mechanisms of bioclogging and biosurfactant production. Results indicate tertiary flooding of the micromodel system with biomass and biosurfactant was optimal for oil recovery due to the combined effects of bioclogging of the pore-space and IFT reduction. However, metabolic by-products alone were able to recover oil in some cases dependent on wettability. Unaided biomass (i.e. no biosurfactant) that clogged the pore-space also successfully produced additional oil recovery. When analyzing residual oil blob morphology, MEOR resulted in oil blob size and radius of curvature distributions similar to those obtained by an abiotic capillary desaturation test, where flooding rate was increased post secondary recovery. Furthermore, for the capillary number calculated during MEOR flooding with bioclogging and biosurfactant, lower residual oil saturation was measured than for the corresponding capillary number under abiotic conditions. These results suggest that bioclogging is a potentially effective approach for pore morphology modification and thus flow alteration in porous media that can have a significant effect on oil recovery beyond that predicted by capillary number.
Ceramic Screens, an Innovative Milestone in Sand Control
Authors: Müssig S. , Henriksen P. E , Wildhack S. , Lesniak C. 
Published: October 2011

Abstract
The Danish offshore oil and gas fields in the Danish Underground, operated by Maersk Oil on behalf of the DUC (Danish Underground Consortium), which is a collaboration between A.P. Møller - Mærsk A/S, Shell Olie- og Gasudvinding Danmark B.V. (Holland) and Chevron Denmark Inc., are of mainly tight Cretaceous carbonates with permeabilities of 0.5 - 2.5 mD.
In order to establish economical production rates all the wells need to be stimulated before they can be set on production. DUC is using two types of completions, the CAJ (Controlled Acid Jetting) - liner principle [Hansen, J.H. et al. 2002] and the PSI (Perforate-Stimulate-Isolate) principle [Damgaard, A.P., Bangert, D.S., Murray, D.J., Rubbo, R.P., and Stout, G.W. 1992]. The latter is used when hydraulic fracture operations have been selected for stimulation. Experience showed that during cleanup operations and during the production significant erosion may occur due to backflow of proppant contributing to increased health and safety risks. Operations also faced the problem of sand spreading across the entire facilities and pipelines creating production downtime. In addition resin coated sand having been classified as a "red" chemical in the Danish sector a solution was required to remove its use. Therefore the operator and ESK designed and developed a new sand screen based on ceramic material, which is able to keep the sand out of the production stream and having enough strength to resist the erosional forces. In this paper the development of the ceramic screens is described, and their deployment in two applications is presented: In the first example, the ceramic screen was engineered particularly for preventing proppant flowback in propped fractured reservoirs. For the second application, the ceramic screen was designed as a regular sand screen to stop sand flow from the unconsolidated sand propped fracture.
In addition to the screen development, production results will be discussed for the ceramic screens applied in the PSI completions of two oil production wells in the Valdemar field as well as in a gas production well in the Tyra field.
Geosteering with Sonic in Conventional and Unconventional Reservoirs
Authors: Pitcher Jason , Market Jennifer , Hinz David 
Published: October 2011

Abstract
Azimuthal variations in sonic logs have been observed for many years, both in wireline and LWD data. Rudimentary reactive geosteering methods have been used in the past, including drilling until real-time sonic log detected a change in formation velocity and subsequently altering the wellbore trajectory.
We propose taking sonic geosteering a step further by providing real-time azimuthal images showing the velocities as they vary around the wellbore. Images can also be transmitted at both shallow and deep depths of investigation to determine how close an approaching boundary may be.
While more traditional geosteering measurements, such as resistivity and gamma ray, are highly suitable in many cases, there are instances where the resistivity or gamma ray contrast between beds may be low or the depth of investigation very shallow, making geosteering problematic. However, in such environments, there may well be a porosity contrast, detectable as velocity differences by the sonic tool, which are more suitable to geosteer with. In addition, sonic logs are an ideal way of determining gas contact points in a reservoir, as compressional velocity measurements are highly sensitive to gas.
For unconventional shale reservoirs, sonic anisotropy and its relationship to rock mechanical properties are a principle determinant of a well-placement strategy.
In this paper, we explore some key factors of sonic geosteering, such as depth of investigation, azimuthal resolution, and compressional vs. shear velocity responses. A workflow for integrating azimuthal sonic measurements into existing visualization and geosteering software is described. Field data examples are presented, showing the feasibility of sonic geosteering as well as its current limitations.
Validation of T2-Bin Derived Permeability - A Case Study in Carbonates
Authors: Kneedy Jason , Smith Charles H , Ramakrishna Sandeep 
Published: October 2011

Abstract
The Atoka Wash in Oklahoma is a segment of the arkosic detrital material that eroded from the Wichita Mountain uplift. The rock ranges in age from Precambrian to Middle Pennsylvanian. The distinguishing characteristic is the composition of carbonate matrix material. The deposition can vary from finely grained to very course, depending upon the energy of transport.
Petrophysical properties of this rock contributed to confusion over the ability of the rock to produce hydrocarbon and the volume of reserves possible. Standard triple-combo logs were the logs typically run to evaluate the formation. Completions would be attempted when density/neutron crossplot porosity was in excess of 8%. Still, many completion attempts were unsuccessful, as the reservoirs would not produce at commercial rates. As one unsuccessful attempt followed another, drilling for this horizon became a discouraging and costly business.
The advent of T2 bin-derived permeability from NMR measurements cast this formation in a new light. NMR logs were used to evaluate other horizons in wells, and data was acquired in certain wells where mud logs indicated shows in this Atoka Wash. The surprising result was the existence of high-permeability areas in parts of the well with very low porosity. Some wells had indicated density/neutron porosity of less than 3% but with excellent indications of permeability from the T2 bin distribution. Completion attempts were made in some of these NMR-indicated productive zones with excellent results.
This paper presents the observed logs and the techniques used to ascertain these productive horizons. The usefulness of NMR bin-derived permeability to design completions is also emphasized. Finally, we will provide a comparison of the calculated productivity versus actual production for a series of these Atoka Wash wells, thereby validating the derivation and application of this NMR T2 bin-derived permeability.
Novel Transient Electromagnetic Borehole System for Reservoir Monitoring
Authors: Dutta Sushant M. , Reiderman Arcady , Schoonover Larry G. , Rabinovich Michael B. 
Published: October 2011

Abstract
In this paper we describe a novel transient electromagnetic borehole system for reservoir monitoring that has important advantages over existing borehole electromagnetic technology. This work is based on computer simulations of waterflooded reservoir models that demonstrate the effectiveness of this technology for reservoir monitoring.
Conventional and enhanced oil recovery processes such as waterflooding, steam flooding, and chemical flooding cause key changes in reservoir fluid composition over time. The proposed transient electromagnetic borehole technology can be used for fluid-front monitoring and to detect bypassed pay in reservoirs.
Existing cross-well borehole electromagnetic technology has shown potential for detecting changes in the reservoir over time by measuring resistivity contrasts. However, this approach has limitations, most notably that the measurements are limited to the region between a pair of wells. We show that transient measurements have a distinct advantage over traditional continuous-wave measurements in that different segments of the transient signal can be mapped to different regions of the formation. Furthermore, the measured transient signal experiences no interference from the transmitter because the transmitter is silent when the formation signal is acquired. This technology eliminates the need for using at least two separate wells simultaneously, and it results in better spatial resolution for the region close to the well. We use a realistic model of a waterflooded reservoir as a benchmark to present several three-dimensional (3-D) transient simulation results, demonstrating that this technology can provide deep (up to 300 m) and azimuthally selective measurements.
As opposed to cross-well technology, the proposed technique does not need a multifrequency, multispacing transmitter-receiver system or wireline logging equipment. It can be implemented as a permanent sensor system in the borehole. It can potentially also be used to monitor CO2 movement in carbon capture and sequestration (CCS) applications. The 3-D transient electromagnetic computer simulations performed for this work are a significant addition to the knowledgebase of the industry.
Expansion of Field Testing and Application of New Hybrid Drill Bit
Authors: Dolezal Tisha , Felderhoff Floyd , Holliday Alan , Bruton Greg 
Published: October 2011

Abstract
Improvements in drilling performance in key applications around the world continue to focus on reducing vibrations of the system consisting of the drill bit, bottomhole assembly (BHA) and drillstring. These vibrations can take the form of whirl, stick-slip, bit bounce or combinations of these, leading to drilling inefficiencies. Many efforts are under way to control and manage these vibrations and develop tools that can withstand the higher vibrations seen in today's drilling environment.
Introduction of the most-recent design of a hybrid drill bit took place in 2009 with the presentation of IADC/SPE paper 128741. It was shown to be a viable drilling tool for potentially difficult or problem-prone applications. This paper covers the ongoing development work on the hybrid bit technology which combines elements of polycrystalline diamond compact (PDC) and tungsten carbide insert (TCI) bits. Testing is now taking place on a large scale and the results confirm the potential benefits revealed in the early prototype testing.
Early tests of the hybrid bits were designed to show that it is sufficiently robust to drill and hold up under normal drilling. The next 100+ runs were targeted at areas where both traditional PDC and TCI drill bits struggle and the hybrid bit proved to be both faster and more durable than the conventional bits. This was achieved through the synergy of the smooth running action of the rolling cutters with the sharp cutting elements on the fixed PDC bit blades.
This paper details the knowledge gained in drilling over 167,000 feet just over 10,100 hours that has led to further design improvements and a better definition of the applications in which a hybrid bit can deliver superior performance. These applications are generally in the harder and hard-interbedded formations. The targeting of the hybrid technology is enabling problem wells to be finished sooner and at lower cost while still avoiding dynamic dysfunctions commonly seen. Results of all hybrid runs in a wide range of applications will be compared and recommendations will be made on where this technology can provide the most significant improvements.
Field Application of a New Proppant Detection Technology
Authors: Duenckel Robert J. , Smith Harry D. , Warren William A. , Grae Abram D. 
Published: October 2011

Abstract
Traditional proppant placement evaluation in hydraulically induced fractures has utilized detection of radioactive tracers pumped down hole with the proppant. We are proposing new methods for proppant placement determination. The proppant placement determination method described in this paper eliminates down hole placement of radioactive materials. A thermal neutron absorbing compound is inseparably incorporated into a ceramic proppant during manufacturing in sufficiently low concentration that it does not affect proppant properties. Proppant is detected using standard compensated neutron tools or pulsed neutron tools, with detection based on the high thermal neutron absorptive properties of the compound relative to downhole constituents.
Specifically, proppant is detected using after-frac compensated neutron logs combined with corresponding before-frac logs. Increased thermal neutron absorption by the compound reduces count rates in the near and far detectors, with approximately the same percentage reduction observed in each detector, leaving the N/F ratio unchanged. One detection method utilizes a comparison of before-frac log count rates and after-frac count rates, with reduced after-frac count rates observed in zones containing proppant. A second detection method, especially useful when formation gas saturations change, involves only the after-frac log. Since the near to far detector count ratio is unaffected by proppant, after-frac count rates predicted from the ratio will also be unaffected. These computed/synthetic count rates will be greater than the observed after-frac count rates in intervals containing proppant.
This paper will describe the results of applications of the new detectable proppant in wells in South Texas and Wyoming. The location of the detectable proppant was determined from analysis of before-frac and after-frac compensated neutron logs.
Advanced Logging-While-Drilling Formation Evaluation Case Study, North Slope, Alaska
Authors: Hastings Doug , Armfield Bart , Hupp Douglas 
Published: October 2011

Abstract
Efficient operations are critical to the successful development of North Slope, Alaska, prospects where an abbreviated drilling season and rig-time costs constrain project planning. Logging While Drilling (LWD) provides the real-time data used to make essential well construction decisions. In addition, data are acquired in troublesome formations with complex well profiles where acquisition of wireline data would be overly risky or sometimes impossible. This paper highlights a particular case in which one operator used LWD technology and strategic evaluation to manage risk and significantly reduce operating costs while drilling a well in the Sag River formation.
The Sag River formation is fine-grained sandstone with variable permeability controlled by porosity and lithology. The permeability profile causes a significant transition zone at the oil/water contact. Reservoir engineering studies require an accurate understanding of the formation permeability to determine the optimal well placement strategy, and horizontal wellbores are necessary to maximize exposure in the most productive zones. Considering these factors, it is critical to understand permeability, pore size distribution, traditional porosity, and saturation properties for successful development.
Because of considerable wellbore stability risk in the Kingak shale, LWD services were used to acquire reservoir data. The LWD services used to evaluate this reservoir measured bulk density, neutron porosity, gamma ray, resistivity, spectroscopy, capture sigma, magnetic resonance porosity and T2 spectrum, permeability, pore size distribution, annular pressure, formation pressure, and a computed mobility. Acquiring the necessary formation data with LWD tools saved 3 days of rig time and eliminated stuck tool and fishing risks associated with wireline evaluation. Furthermore, a casing string that would have been used to facilitate prolonged reservoir evaluation operations after drilling was eliminated.
Data interpretation showed that the Sag River formation at this location was oil bearing and that the higher-than-expected water saturation was actually bound water. The spectroscopy results helped refine the clay volume as well as the volume of non-quartz minerals. The results of this evaluation will be used in subsequent reservoir modeling to identify the best approach to exploiting this reservoir. A comparison of the core evaluation with the petrophysical interpretation is also presented.