bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancement of Vorwata Field Reservoir Model by Integration of Pressure Transient Analysis with Real-Time Downhole Pressure Data
Authors: Setiawan Agus , Hird Kirk B. , Curtis Bennett O. 
Published: January 2012

Abstract
Vorwata is a giant gas field located in Bintuni Bay, Papua Barat Province, Indonesia. The field was discovered in 1997 and currently produces approximately 1.3 bcf/d of dry gas from the Roabiba sandstone reservoir. Initial development consists of 14 wells drilled from two platforms. The wells produce through 7-inch tubing and have been tested up to 240 mmscf/d. A Permanent Downhole Pressure Sensor (PDPS) is installed in each well to continuously monitor downhole pressure and temperature.
Vorwata field is a faulted, high sand quality reservoir. The impact of faults on reservoir performance was very uncertain prior to startup. There was great concern the field could be compartmentalized, or at least strongly influenced by flow baffles and barriers. One of the primary subsurface objectives during pre-startup testing was to assess lateral and vertical reservoir connectivity within the development area.
Pressure build-up tests (PBU) were conducted in each well as part of the initial clean up and testing procedure. The initial tests were very helpful in characterizing offset faults. PBUs obtained once the field was put on production are influenced by interference from offset wells, masking any boundary effects. Interpretation of the PBUs is enhanced by applying deconvolution. A pre-startup interference test successfully identified lateral and vertical pressure communication within the development area. The well/fault geometries and reservoir connectivity characteristics obtained from the PBUs and interference test have been used to condition the static and dynamic models.
This paper describes the well testing program that has been implemented to reduce reservoir uncertainty in the Vorwata reservoir during the early phase of field development. Well test and pressure interference results have been integrated into full-field models to better assess future field performance and development decisions.
Optimization of Equity Redeterminations through Fit-for-Purpose Evaluation Procedures
Authors: Worthington Paul F. 
Published: January 2012

Abstract
Equity redetermination is most commonly encountered where a straddling field is developed as a discrete entity through a process of unitization. It is enacted through evaluation procedures that prescribe the technical methodology for requantifying different license shares, or tract participations, in a field unit as more data become available. The formulation of these procedures usually takes place at unitization, it is based on appraisal data, and therefore it is guided by simplified perceptions of reservoir character. For this reason, many such technical procedures have been found to be lacking when they are applied later at the equity redetermination stage. These shortcomings can take the form of ambiguous wording, misleading definitions, technically-inappropriate specifications, contradictory prescription, or simply a lack of sufficient detail to render the intended process meaningful. They have impeded the determination of revised tract participations by triggering inter-license disagreements that might otherwise have been avoided.
With the objective of reducing this unhelpful impact, experience of redetermination situations is used to illustrate the nature and consequences of poorly constructed procedures for the recomputation of tract participations. The analysis is then flipped to generate a framework of key elements of technical procedures together with indications of how they are best implemented. These matters form the basis for a high-level set of protocols for a more efficient and effective redetermination of equity that would avoid the previously encountered shortcomings. The protocols encompass the proper incorporation of data character, a sound technical basis for redetermination, a balance between under- and over-prescription, an auditable deterministic ethos, and adherence to good international petroleum practice. They constitute recommendations for a better approach to the compilation of fit-for-purpose evaluation procedures within those unitization agreements that make provision for a future redetermination of equity. The recommendations are equally applicable to domestic and international unitizations. The principal benefit lies in an enhanced efficiency of the equity-redetermination process, which feeds through to a greater collective asset value.
Real-time Geomechanics Optimizes Drilling 4 Deep Water Wells in Kutei and Tarakan Basin - Offshore East Kalimantan
Authors: Capone Graziano , Bucari Giovanni , Bahuguna Somesh , Setiawan, Ngurah Beni 
Published: January 2012

Abstract
Oil and Gas exploration in deep water poses significant challenge of drilling through narrow mud weight windows with little margin for error. A thorough pre-drill planning complemented with more informed real-time risk detection and intervention while drilling the well, ensures efficient and safe drilling. This paper is a summary of one such recent successful drilling campaign.
In 2010, Eni Indonesia one of the big operators in Indonesian deep water, drilled 4 Deep water wells in varying water depths as deep as 2700ft in Kutei and Tarakan basin, offshore East Kalimantan. Real-time geomechanics services were employed to provide estimate of safe mud weight windows while drilling to the drillers. Under this service in the planning phase, pre-drill pore pressure models generated for each of the planned wells, revealed over pressured reservoirs with narrow drilling margin between pore pressure and fracture gradient. In the execution phase, a customized workflow was followed to ensure that correct pore pressure is estimated in real-time using all the available log and drilling data generated while drilling and that only properly interpreted and validated safe mud weight windows is communicated to the drilling team on board the drill-ship and town through a flag-based communication tree.
Geomechanics engineers working onboard the drill-ship ran proprietary software which streamed in real-time logging-while-drilling data – Gamma Ray, Resistivity, Density and Neutron porosity logs, caliper etc. Using these logs multiple pore pressure and fracture gradient estimates were generated in real-time. These estimates were interpreted in conjunction with drilling mechanics, mud logs, cuttings analysis, Equivalent Circulating Density and Equivalent Static Density to generate safe mud weight windows. This window was further calibrated during drilling with wireline and logging-while-drilling recorded formation pressure measurements and leak-off tests. Real-time update of safe mud weight window enabled several critical decisions like altering casing depths and mud weight management.
Introducing the Concept of Sustainable Geothermal Management in Indonesia
Authors: Amar Meutia S. , Kustino Huri 
Published: January 2012

Abstract
The generic issue of sustainable geothermal energy management is discussed, based on the UN principles of sustainable development, and on Indonesia’s national legal implementation mandated by the newly promulgated Act No 32/2009 and its regulatory derivatives. The development of a comprehensive assessment framework of sustainability indicators is introduced, taking into consideration economic prosperity, environment and social justice. Sustainable development as defined by the World Commission on Environment and Development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs. This definition is inherently vague, and is often misunderstood or misinterpreted.
In an attempt to link sustainable development to the management of geothermal resources, two approaches are introduced: BLUE sustainability which assumes the validity of growth and places equal importance on environment, social justice and economic prosperity; and GREEN sustainability having the environment as a comprehensive baseline foundation for social justice and economic prosperity.
In simple terms, GREEN sustainability focuses on the capacity of any given geothermal system to sustain exploitation, whereas BLUE sustainability focuses on economic forces and technological advances. The basic framework of P3 (People, Planet and Profit) is utilized to explore an equilibrium model for a typical geothermal energy project, using indicators for social, business/economics and the environment derived from the Global Sustainability Reporting Initiatives.
New Openhole Technology Unlocks Unconventional Oil and Gas Reserves Worldwide.
Authors: Rivenbark Mark , Dickenson Robert Wayne 
Published: January 2012

Abstract
Open hole, multi-stage (OHMS) fracturing systems were introduced in 2001. Since then, this technology has been credited with unlocking oil and gas reserves around the world that were previously dismissed as unavailable or uneconomic, enabling companies to maximize production in tight rock formations and mature oil fields. OHMS systems have been run in every type of formation from the much heralded shale gas plays in North America to the massive carbonate formations in Saudi Arabia and have also been used in offshore wells in the North Sea, Black Sea and West Africa.
This paper focuses on the open hole packer used in OHMS systems to generate the annular compartmentalization necessary for effective multi-stage stimulation and production. This packer is a dual element, hydraulic-set, mechanical (DHM) packer and provides reliable open hole isolation with various benefits compared to swellable, inflatable and other mechanical packers including: 1) Reduced torque and drag due to their short length (average 5 ft) with only two short sections of rubber with a minimum running outside diameter, 2) Creation of two independent sealing points via dual elements, which together act like a single, 3 ft long seal with redundant sealing, 3) No need to formulate them for specific downhole fluids or wait for them to swell, 4) No thermal contraction such that the seal is not lost during stimulation, and 5) The rubber element does not reduce its durometer rating when set.
Laboratory testing and field applications of the DHM packer are presented including HPHT, multi-laterals, proppant fracturing and acid stimulation with on and offshore case histories incorporating stand alone screens, acid jets, fracture ports and combinations thereof.
Wellbore Stability Analysis in the South China Sea: A Case Study
Authors: Cai Jun , Shao Shijun , Zhang Chao , Qiu Kaibin 
Published: January 2012

Abstract
The paper describes a case study in the South China Sea in which drilling problems were successfully addressed through a wellbore stability analysis. The wellbore stability analysis started from understanding of the drilling history of offset wells. A specially designed drilling event review plot, which categorizes and organizes all drilling problems in a graphical display, was used as to illustrate drilling and borehole failure history for the two offset wells in the study area. A mechanical earth model was constructed by following a systematical workflow with emphasis on reducing uncertainty of the in-situ stresses. The synthetic borehole failure image was used to provide an excellent visualization of borehole failure forecast, which made it easily understandable even for geomechanics non-experts and was comparable to the borehole failure observations from caliper logs and borehole image data. A drilling map was constructed to provide a user-friendly presentation of the outcome of the wellbore stability analysis. This improved the communication among all drilling stakeholders. Based on the results provided from the analysis, engineers revised the setting depth for 9 5/8-in. casing to reduce drilling risk. Post-drilling analysis showed that there was substantial improvement in the subsequent drilling performance for the planned well compared to that for the previous wells.
This paper illustrates that incorporating wellbore stability analysis as part of the well planning process allows the drilling team to optimize the casing design and drilling mud weight to minimize wellbore instability and improve drilling performance.
A Strategic Method to Accelerate Individual’s Learning and Enhance Subsurface Team Performance within Multidisciplinary and Multi-generational Environments
Authors: Dashti Qasem , Gunawan Christine 
Published: January 2012

Abstract
The development of young geoscientists and engineers to be independent contributors is paramount for Kuwait Oil Company’s long-term success in optimizing their production and improving field development efficiency. In our fields, main challenges are characterized by the deep and tight naturally fractured carbonate reservoirs, volatile fluids, high pressure high temperature conditions and the presence of CO2 and sour gas.
Production enhancement activities play a significant role in maintaining production capacity. Therefore, rapid and integrated decisions from multidisciplinary teams are necessary to select potential solutions and to accelerate the required remedial work. Yet the largely junior population of the asset teams creates an immense challenge in getting the work completed.
Overcoming this challenge begins by developing individual staff learning programs that are aligned with competency gaps, business needs and personal development plans. The program lists the competencies required, which are then achieved through blended learning. The learning program emphasizes transferring knowledge and skills on the job, and holds the learner accountable for achieving results. Therefore, linking training with relevant and appropriate task assignments is essential to accelerate and reinforce competency development. One task which has proven key in the blended learning methodology is conducting formal and detailed well reviews, in which all pertinent data is presented on a specific well, and a multi-disciplinary team brainstorms and recommends an action plan and the additional. Staff assigned to conduct well reviews must develop knowledge outside their domain in order to facilitate team collaboration among the different disciplines, allowing the sharing of best practices and optimum decision making.
This accelerated staff development method has been applied for two years in North Kuwait and has resulted in meeting our production goals, better field management and improved team performance. Some examples of activities enabled by this methodology are defining perforation intervals, developing sector reservoir models to determine shut-in periods required for buildup testing, and formulating workover program design. In these two years 12 workover programs have been completed successfully – is an outcome of 66 well reviews. Just as importantly, junior staff competency grew 48%, an achievement which is mainly the result of their being assigned and performing jobs such as well data analysis and well reviews with minimum supervision.
This paper details the method and progress of what has proven to be the best approach to accelerating staff learning curves, reducing competency gaps and enhancing professional development that delivers. Also summarized is the value of team collaboration, interaction between engineers and geosciences for successful reservoir management, and lessons learned.
Impact of Electrical Surface Charges and Cation Exchange on Oil Recovery by Low Salinity Water
Authors: Nasralla Ramez A. , Nasr-El-Din Hisham A. 
Published: January 2012

Abstract
Low salinity water is a promising technique for improving oil recovery in sandstone reservoirs. However, the mechanisms of low salinity water are still uncertain; that makes the optimum conditions are unknown. In this paper, we study the effect of cation type and concentration in the injected water to identify the optimum salinity. Coreflood experiments of waterflooding and cation exchange tests were conducted to investigate the impact of cations on oil recovery, and understand the rock/brine interactions. In addition, zeta potential at oil/brine and rock/brine interfaces were measured to examine how the cation type and concentration change the electrical surface charges, and relate these measurements to the oil recovery obtained from coreflood.
Berea sandstone cores were used for waterflooding and cation exchange experiments; all coreflood experiments run at HPHT. Three concentrations of NaCl, CaCl2, and MgCl2 were tested with two crude oils of different compositions and properties. ICP-OES, and a spectrophotometer were used to analyze the ions concentrations in the effluent fluids for both waterflooding and cation exchange tests. Zeta potential was measured for solutions of oil/brine, and solid/brine; the solids used were Berea sandstone and four types of clays.
This work contributes to the understandings of the impact of electrical surface charge and cation exchange on oil recovery by low salinity waterflooding. Zeta potential results showed that Na+ changes the electrical charge at both oil/brine and rock/brine interface to highly negative, which results in repulsion forces between the two interfaces, and hence wettability alteration and improvement in oil recovery. Moreover, waterflood experiments of NaCl solutions improved oil recovery significantly compared to CaCl2, and MgCl2. Analysis of core effluent fluid proved the interaction between brine and rock; injection of single cation brine leached some of the ions from the rock surface by exchanging cations, which could contribute to improvement of oil recovery. Results demonstrate that the existing cations in the injected water brine have more dominant effect on the recovery factor than the water salinity. These findings can help in defining the brines that have higher potential for oil recovery improvement.
Maari Field Development – Case Study
Authors: Mills C. R. , Marron A. , Leeb W. J. 
Published: January 2012

Abstract
The Maari Field in the offshore Taranaki Basin, New Zealand was discovered in 1983 by the Moki-1 exploration well (figure 1). Appraisal activities and development studies undertaken by various oil companies over the subsequent two decades failed to identify a viable development concept with an acceptable risk profile. Key factors delaying development were distance from existing infrastructure, field size in association with oil price and critically the high wax / low pour point nature of the oil. The Maari Joint Venture identified a strategy to develop the field and produce the previously stranded oil by means of innovative technology applications.
The self-installing wellhead platform and the FPSO were installed in April and May 2008, respectively but the jack-up rig to drill the five horizontal production and three deviated water injection wells was delayed by three months due to winter weather. First Oil from the field was on 25th February 2009, a milestone achieved some 25 years after its discovery.
A number of new technologies and pioneering applications were put into practice with the Maari field development: The self installing wellhead platform. At the time Maari WHP was the largest self-installing platform of its kind.The production wells have a thermal design with both passive (thermal gel and thermal cement in the annuli) and active (electric down hole heating system) elements.Drilling while casing.The electric submersible pump assemblies were designed to handle free gas conditions down hole in the horizontal section due to the reservoir fluid being close to its bubble point.The injection water is heated to reservoir temperature to avoid wax precipitation in the reservoir and injected above the ‘fracture pressure’.
Two smaller near field satellite oil accumulations were also drilled and completed, including a ~8,000m horizontal ERD production well targeting a deeper reservoir in separate structure to the south of Maari. Numerous challenges, such as scale, hydrogen sulphide, corrosion, completion designs and wax, have been encountered and largely overcome during the production phase.
The paper will detail the innovations, new technologies, major learnings and experiences from the development concepts to production of this originally ‘stranded’ asset.
An Integrated Petrophysical Analysis to Evaluate Sequence Stratigraphy of the Winduck Interval in the Neckarboo Sub-basin, Darling Basin, NSW
Authors: Khalifa Mohamed , Alta’ee Ali F. 
Published: January 2012

Abstract
The latest Silurian to Early Devonian Winduck Interval of the extensive but poorly exposed Neckarboo Sub-basin, consists of several thousands of metres of a quartzose siliciclastic sandstone succession that has been divided into three sequence divisions called (in ascending parasequence order) parasequence A (coarse-grained quartz sandstone), parasequence B (fining-upward succession of sandstone with siltstone and sandstone beds thicken upward) and parasequence C (coarse-grained quartz sandstone with siltstone and interbedded calcareous sandstones). These three geophysically defined parasequences are separated by slightly discordant erosion surfaces. The erosion surfaces are characterised by abrupt breaks at the top of parasequences A and B and the surface at the top of parasequence B represents relatively local erosion. The top of parasequence C is marked by a major unconformity with the Snake Cave Interval. Gamma ray and self-potential signatures within the parasequences can be correlated throughout the Neckarboo Sub-basin. The three sequence divisions are further subdivided into depositional parasequences, which are readily recognised from core sedimentology and electrofacies analysis. The parasequences provide the framework for a detailed sedimentological analysis, which focuses on the identification of lithofacies successions and parasequences. Petrophysical data are recorded and their relationships to the depositional parasequences are discussed. This paper presents a predictive reservoir effectiveness model that has been developed to aid exploration of the Winduck Interval. The aim is to find the distribution of parasequences (based on variations in porosity, net effective thickness and lithofacies with burial depth) and to provide a dataset for lithostratigraphic units within the Winduck Interval and parameter input for exploration prospect evaluation. Parasequence stratigraphic analyses were obtained where there is good lithofacies control. The porosity and permeability results have been analyzed in a number of parasequences and poor reservoir quality may be due to the effects of structure and fluid flow. This approach provides for better and more precise stratigraphic trap analysis.