bluuebunny/crossref_metadata_2025 huggingface dataset:
Adding Value to Oil and Gas Fields through Systematic Full Field Reviews
Authors: Balnaves C. , Bangkong S. , Herweijer J. , Irrgang H. R. , Khurana A. K. , Lammerink W. , Palmer I. D.
Published: December 2007

A Full Field Review (FFR) is a comprehensive multi-disciplinary integrated re-evaluation of all basic reservoir characterisation data, dynamic reservoir and well performance data as well as relevant surface facilities pertaining to an oil or gas field to maximise knowledge and understanding of the field. The basic purpose of FFRs is to formulate and maintain evergreen initial and ongoing development plans to maximise full lifecycle value of the field. FFRs are a key component of integrated reservoir management.

Pre development FFRs are standard industry practice, their value is well understood and are prerequisites to development approval by regulatory authorities and budget sanction by corporations. Brownfield FFRs on the other hand are conducted on an ad-hoc basis.

We believe that systematic, timely and well focused brownfield FFRs add significant value by identifying potential production and reserves optimisation opportunities in and around brown fields. Most value is added by questioning prevailing assumptions, seeking and explaining anomalies, finding creative solutions and looking for opportunities to add value through application of new technologies. The importance of mutually optimising the reservoir, wells and surface facilities cannot be overemphasised.

Alternative static and dynamic realisations of the reservoirs are tested under different operating strategies via reservoir models to search for additional development opportunities, not only within the field under study but also in its geographic proximity so as to utilise and/or build upon the existing surface facilities and infrastructure. FFRs also help in justifying reserves reclassification of probable and possible reserves into higher categories. Alternatively they can identify appraisal and data requirements to justify such reserves reclassification.

The Malaysian regulatory regime administered by the Petroleum Management Unit (PMU) of Petronas formally requires its production sharing contractors to conduct periodic brownfield FFRs. This paper reports the results of a 2005 PMU sponsored benchmarking study of international industry and regulators' Full Field Review best practices. Results of implementing FFR outcomes in three fields together with predictions of four further FFRs completed to date on Malaysian fields are also provided.
A Systematic Approach to Incorporate Capillary Pressure-Saturation Data into Reservoir Simulation
Authors: Wang Y. , Bandal M. , Moreno J. , Sakdilah M. Z.
Published: December 2007

The Capillary-saturation function plays an important role in describing fluid distribution and modeling flow in reservoir simulation. In our full field review, a systematic procedure was developed to establish a capillary pressure-saturation correlation honoring various sources of information such as laboratory measurements and well log data in the following steps:

Laboratory capillary pressure and saturation data of a variety of measuring methods were processed to represent capillary pressure versus saturation at reservoir conditions. A method was established to determine the practical transition zone height and irreducible water saturation. A reliable correlation between the irreducible water saturation and rock quality index was derived, and the normalized saturation was calculated. Capillary pressure was normalized using the J function, and an optimal correlation of the J function and normalized saturation was established.

Following these steps, a normalized capillary pressure-saturation function including values for rock-quality dependent irreducible water saturation and end-point capillary pressure was established for simulation use. During upscaling of the fine scale geological model to the relatively coarse flow simulation model, one of the key goals is to preserve the hydrocarbon volumes from the fine scale model. Several approaches were tested. Advantages and disadvantages of each method were investigated and an optimum method was chosen for the study that was robust and yielded satisfactory results.

This paper describes our approach and addresses the following important practical issues:

determination of irreducible water saturation and transition zone height, normalization of capillary pressure and saturation, and preservation of hydrocarbon volumes during upscaling.

The optimal solutions to these issues are discussed. The application of the method to our full field study is presented.
Rapid Pressure Support for Champion SE Reservoirs by Multi-Layer Fractured Water Injection
Authors: Sommerauer G. , Zerbst C.
Published: December 2007

The Champion field is a large oil field offshore Negara Brunei Darussalam. This paper discusses the-for us-novel application of multi-layer fractured water injection into three shallow reservoirs in the Champion Southeast field (CPSE). The project is part of a larger secondary recovery implementation scheme and future efforts to increase economic oil production and ultimate recovery in the whole Champion field.

The main boundary condition for the rapid water injection project is the use of existing infrastructure with the exception of three new water pipelines and nine new wells. This paper describes the following:

Reservoir setting and production history. Water injection philosophy. Design considerations for fractured water injection including: ○ Pressure requirement to design for fractured water injection. ○ Simulation of fracture growth and containment and resulting conclusions. Design considerations for the multi-layer fractured water injector wells including: ○ Selected Drilling Aspects (well trajectory, drill-in fluid, formation evaluation, casing scheme). ○ Completion Design Considerations (clean-out, perforating, sand control, selectivity, "smartness", other). ○ Material selection.

One of the main conclusions is that fracture growth and containment is not a major issue in soft, high-permeable formations. The main challenge is in drilling the sometimes-demanding well trajectories and running the ("smart") completions in these wells with small tolerances.
Water Control and Fracturing: A Reality
Authors: Mahajan M. , Rauf N. , Gilmore T. , Maylana A.
Published: December 2007

Water production in mature fields is a common situation. In many mature areas, every barrel of oil is being produced with six to ten barrels of water. The production of water results in increased operating expenses along with other water related well problems like scale, fines migration, sand face failure, water loading in wellbores etc.

The goal of any hydraulic fracturing treatment is to increase the production potential of the well. This is achieved by parting the formation rock under pressure and leaving it "propped" open to create more conductive path between the reservoir and wellbore. This technique has become a common and routine method of stimulating oil or gas wells.

Many operators do not associate the stimulation and water control objectives in the same treatment. In fact, it is usually the opposite; the candidate is rejected for a hydraulic fracturing stimulation treatment because of the fear of increasing the water rate. This should not be the case for a few reasons. The first, a mature well will produce water with or without the hydraulic fracture treatment. The second, the emergence of a new stimulation technique over recent years that combines water control technology as part of the hydraulic fracturing treatment, offering the potential for reduced post frac water cut with the gains in productivity that a hydraulic fracturing treatment can offer.

The conformance fracturing technology opens the possibility to stimulate high water cut wells while controlling the water simultaneously. This is achieved by using specially designed relative permeability modifiers (RPMs). By placing the RPMs in the fracturing fluids, resistance to water flow will occur in the filtrate-invaded area opposite the fracture faces. The conformance fracturing treatment generally results in a net increase of oil flow with reduction in the water cut.

This paper will review the evolution and progresses made in the field of conformance engineering with special focus to their applications in conjunction with fracturing treatments. It will describe the successful application of conformance fracturing technology in a mature field in South Sumatra, Indonesia. The placement method, RPM technology and the field case histories of successful treatments shall be discussed in order to substantiate the technology.
Research on Remaining Oil Distribution and Further Development Methods for Different Kinds of Oil Layers in Daqing Oilfield at High Water-Cut Stage
Authors: Chengfang Shi , Qinglong Du , Lihong Zhu , Shanyan Zhang , Lei Zhang , Xiaowei Jian
Published: December 2007

Daqing oilfield is multi-layered sandstone oilfield with serious heterogeneity1. After more than 40 years flooding, the oilfield has entered the high water-cut stage when the water flooding and polymer flooding are coexisting. After multi infill drilling and multi adjustments, different kinds of oil layers have been swept with certain degree, and the remaining oil distributes highly scattered2,3. Three types of oil reservoirs can be divided according to their properties and their grown conditions. Due to the difference in reservoir properties and development strategy, the potential and problems exited for various oil reservoirs are not the same. In Class I oil reservoir, the contradiction is mainly caused by the coexistence of remaining oil, which is resulted by heterogeneity in oil layers, and inefficient water circulation; In Class II oil reservoir, the main contradiction is caused by the coexistence of water flooding and polymer flooding both in vertical and areal; In Class III oil reservoir, two main contradictions are incomplete production-injection structure caused by discontinuous sand body development in areal and interlayer interference caused by too many oil layers in vertical. In view of the main contradictions and problems in different oil reservoirs, and with the consideration of current production technology, the relevant further development measures for different oil reservoirs are determined, and the field application results are fairly good. New methods and techniques to improve the swept volume and displacement efficiency in different oil reservoirs at super high water cut stage are also discussed in this paper.
A High Success Rate Acid Stimulation Campaign—A Case History
Authors: Al-Araimi N. , Jin L.
Published: December 2007

A successful acid stimulation campaign was conducted in 2004 in Brunei Shell Petroleum (BSP). This paper discusses what have been done differently, best practices, and learning.

What is different in this campaign from previous ones? Detailed design

Detailed well-by-well review for first round candidate selection. Fundamental data collection (well data, pressure, formation fluids - water and oil, mineralogy data and lab tests…). Data management system allowing for quick access to well production history data. A design tool (Stim2001) for detailed candidate selection, damage diagnosis, fluid system selection, and job design. QA/QC and compatibility tests aiming to obtain high success rate.

In Brunei Shell, a self-raising rig (BIMA) with a coil-tubing unit on board is used to overcome the limitations due to weather.

A combined pumping procedure (coiled tubing and bull-heading) was implemented to best-fit individual well condition.

Close cooperation among different parties (Well services, Subsurface technology teams, Operation services, and Service providers, etc.)

6000 bpdoe of initial gain was achieved by this campaign in Brunei with high success rate (no failure on single well was recorded).

Confidence level of acid stimulation in Shell Asia Pacific region has been elevated through this stimulation campaign. Lessons learnt and best practices established will be passed to future campaigns. We would like share our belief that acidization is still a good means for stimulating well productivity, but it has to be carried our properly.
Vertically Fractured Well Performance in Rectangular Drainage Area
Authors: Sabaev V. V. , Wolcott D. S. , Mach J. M. , Antipina D. V. , Haidar A. M. , Sviyazova O. O.
Published: December 2007

This paper presents two new models to define the dimensionless productivity index of finite conductivity fractured well either for pseudo-steady state or steady state conditions in the rectangular shape reservoir.

Maximum dimensionless productivity index (JD) of a fractured well in a square drainage is 6/π at pseudo-steady state, and 4/π steady state. The same well in a rectangular drainage can have larger JD with the same area and dimensionless proppant number (Nprop).

Since rectangular geometry provides much larger JD, it seams reasonable to consider this geometry for field development. For a given set of reservoir conditions there is an optimum rectangular geometry aspect ratio (rectangle length width ratio), which when fractured properly, will yield the maximum possible JD under pseudo steady state. Optimizing the aspect ratio impacts the well spacing, which has major significance for field development planning or infill evaluation. The purpose of this work is to provide performance type curves for a fractured well in rectangular drainage area and provide a methodology to determine the optimum aspect ratio for a given set of reservoir conditions.
A Case Study of a Successful Chemical Treatment to Mitigate Asphaltene Precipitation and Deposition in Light Crude Oil Field
Authors: Sanada A. , Miyagawa Y.
Published: December 2007

This paper describes the results of an investigative case study to identify the causes of productivity decline in an oil well and a successful chemical treatment to restore productivity.

A well in a Japanese oil field has suffered from a significant productivity decline from the beginning of commercial production. Pressure build up tests have shown the presence of formation damage becoming larger as production goes. Then we considered the possibility of asphaltene deposition, which has been observed in most of the surface facilities, in the near wellbore formation restricting flow capacity around the well.

A multidisciplinary team was organized, with field operation engineers and researchers from the R&D center, to investigate the asphaltene behavior in the formation and to find the effective way of chemical treatment as asphaltene-control measures.

Laboratory analyses using bottom-hole fluid samples have built the onset pressure curve of asphaltene precipitation, which indicated the asphaltene deposition in the near wellbore region under the production conditions.1

Then the intensive laboratory tests have been carried out to evaluate some commercial additives in terms of their efficiency as an asphaltene inhibitor under the formation conditions and to find the most effective chemical to resolve precipitated asphaltene.

Based on laboratory analyses and tests, a complete chemical treatment program consisting of injection of Xylene into the formation with a three feet treatment radius and squeezing of an asphaltene inhibitor around the well has been designed and applied to the well.

This chemical treatment resulted in a significant improvement in the productivity index which is almost ten times larger comparing as before.
A Constraint Management Based Planning Approach to Delivering Exploration, Development and Production Work Programmes
Authors: MacDougall I. , Saman K.
Published: December 2007

Stuart Petroleum is an emerging independent oil and gas company, operating an exploration, development and production work programme in the Cooper Basin in central Australia. The company's philosophy is to operate as a virtual organization, outsourcing many aspects of its programme in order to leverage the capability of local and international service and technology providers to gain competitive advantage. With an approach such as this, driven by a very small central leadership team, an effective planning capability underpinning effective execution becomes a critical core competency.

Even in a small company such as Stuart, the exploration, development and production programme contains in excess of 5000 key items in any one year, including both office and field activities. Stuart Petroleum uses a state of the art MP-ReMS™ (Multi-Project Resource Management System) planning platform, which dynamically models the oil and gas exploration development programme across the enterprise, based on key corporate objectives.

This capability has yielded significant benefit in optimising resource and materials utilisation and has facilitated substantial cost reductions. Stuart Petroleum has successfully linked its planning strategies directly to its corporate objectives hence connecting the work programme directly to the outcomes achieved for its shareholders. The planning platform models the deployment of critical resources and also tracks milestones in the undertaking of each event, underscoring the priorities of the business.

A Constraint Management approach is employed to accelerate drilling and production hookup of a ranked seriatum of oil and gas prospects with minimal resource and material wastage. This approach offers far greater flexibility compared to traditional time based scheduling methods such as critical path analysis.

The system developed incorporates a "what if" Scenario Analysis capability that allows the leadership team to explore strategic options and their impact on the "current best plan" and corporate objectives.

This paper illustrates the approach taken, highlighting some of the challenges faced and outcomes achieved when managing a large number of concurrent activities competing for finite resources, through effective application of a constraint management approach.
Kutubu: A Rethink
Authors: Williams N. , Lund D.
Published: December 2007

Kutubu is Papua New Guinea's largest oil field. It came on line in 1992 and achieved peak rates of over 130,000 stb/d in 1993 before decline commenced in 1994. Capacity was still 45,000 stb/d at the beginning of 1998 but Kutubu production rates declined rapidly and half the field capacity was lost during 1998 to 2000. It was beginning to look in 2001 as if the field would be completely shut in within a few more years.

Kutubu was originally developed on the basis of a dynamic aquifer (or tilted contact) theory that was used to explain the apparent lack of oil along the northwest side of the field.

A field review conducted by the operator identified an alternate theory of compartmentalisation to explain the non-uniform oil column. As the alternate hypothesis was as good at explaining the early data and better at explaining some of the more recent performance, it was decided to abandon the original concept and test the new theory by drilling in areas the original concept would have predicted to be unprospective. Drilling results were conclusive-there was oil and little or no water in the centre of the field. Consequently, the compartmentalisation theory opened up a series of opportunities in areas that were previously considered unprospective due to the tilted contact concept, and a followup development campaign, along with other projects, has for four straight years completely halted the production decline. The field now appears to have a considerable remaining life of up to 2 decades.
Material Balance Analysis in Complex Mature Reservoirs–Experience in Samarang Field, Malaysia
Authors: Bui T. , Bandal M. , Hutamin N. , Gajraj A.
Published: December 2007

In this paper we present the results of a material balance study for a mature field in East Malaysia. The field consists of several stacked sands and is highly faulted, resulting in a complex system of several compartmentalized reservoirs. The drive mechanisms of these reservoirs range from strong gas cap drive to strong water influx or combinations of these. Fourteen material balance models were built and the results analyzed. This study shows that proper integration of all pressure, production and geological data is critical in defining reservoir compartmentalization and in analyzing the results of material balance (MB) analysis. In particular, analysis of the reservoir production behavior and the fluid contact movement over time is essential in narrowing the uncertainty in the parameters used in the model. In building the MB model, two new techniques were proposed and successfully used:

moving linear regression for generating the input pressure for the MB model production-derived relative permeability data for MB prediction.

Applying these techniques resulted in a well-behaved model and a realistic production profile.
Practical Steps for Successful Identification and Production of Remaining Hydrocarbons Reserves in a Mature Field—Case Study From Tinggi, Malaysia
Authors: Claverie M. , Malek N. A. , Goh K. F.
Published: December 2007

After more than 20 years of exploitation, many of the thick and prolific reservoirs of the Malay basin are depleted. However, field studies indicate that large volumes of hydrocarbons remain located in lower quality but producible layers.

These reserves are the focus of monitoring and recompletion campaigns, to maintain production and extend field life.

Most wells intercept thick accumulations of multi-layered reservoirs, which are produced from dual tubing strings, multiple packers and selectable sliding side doors. In these difficult conditions, special care must be brought to the planning, acquisition and interpretation of monitoring surveys, and to the execution of re-perforation, water shut-off, and other recompletion solutions.

This presentation highlights the practical steps that have led to a successful campaign of identification and production of remaining reserves in the Tinggi field, offshore Peninsular Malaysia.
Water Frac Application in Injectors Improves Waterflooding—An Innovative Approach
Authors: Nainwal S. P. , Das R. , Singh C. B. , Singh S. S. P.
Published: December 2007

Fracturing in water injectors often becomes a pre-requisite to achieve the desired sweep efficiency. The requirement is more pronounced in the injectors with very poor injectivity or poor dissipation. Conventional stimulation techniques like acidisation have not proved to be beneficial. Under such circumstances, a recent foray has been made into the application of water frac.

Water frac is an efficient technique to achieve a limited-length fracture, ensuring a higher sweep efficiency in water injectors. The candidate well is selected after a detailed study by multi-disciplinary team and a customized job schedule is prepared for an initial low-proppant concentration, followed by high concentration at the end to attain higher conductivity near wellbore. Due to zero polymer loading, this technique has the added advantage of low formation damage. There is also saving in chemical and proppant costs. This technique is suitable for not only water injectors, but also effluent disposal wells and polymer flood injectors.

This paper describes the technique and requirements for water frac, along with the case histories. The job design and the results are discussed in details. The benefits accrued have underlined the success of this technique.
Drill-in Fluids for Multi-Lateral MRC Wells in Carbonate Reservoir-PSD Optimization and Best Practices Lead to High Productivity: A Case Study
Authors: Siddiqui M. A. , Al-Ansari A. A. , Al-Afaleg N. I. , Al-Anazi H. A. , Hembling D. E. , Bataweel M. A.
Published: December 2007

Efficient field development requires high quality drill-in fluids (DIF) to minimize formation damage and maximize productivity. This paper discusses the development of least damaging DIFs for multi-lateral Maximum Reservoir Contact (MRC) wells in a newly developed field in Saudi Arabia.

The idea behind the development of DIFs was to avoid fines and polymer plugging by optimizing the loading and Particle Size Distribution (PSD) of fine and medium particles of calcium carbonate.

Several water based DIFs, in the density range of 65 to 70 pcf, were formulated by changing the quantity of fine and medium calcium carbonate with fairly fixed median particle size. These DIFs were tested in the lab on reservoir cores using a dynamic mud flow loop system at simulated reservoir conditions. Tests results indicated 80% return permeability.

Implementation of these optimized fluids in the field with designed practices for maintenance of the quality of DIF during drilling led to high production rates. Twenty five MRC wells so far were drilled using these DIFs. All these wells were production tested with an average PI of almost three times the previously drilled single horizontal wells using the previous DIFs. This high production rate is the result of increased reservoir contact from the multi-lateral wells combined with the optimization of the DIF and the ossociated mud displacement program.
Design and Implementation of a Sand-Control Completion for a Troublesome Shallow Laminated Gas Pay—A Case Study
Authors: Terwogt J. H. , Hadfield N. S. , Van Karanenburg A. A. , Salahudin S. , King K.
Published: December 2007

The Shallow Clastics Field, operated by Sarawak Shell, targets two shallow gas-bearing reservoirs, H1 and H2, at approximately 2,650 ft true vertical depth (TVD). An appraisal/early-producer well with a deviated wellbore was drilled through the H1, H2 targets, and a completion design consisting of a cased and perforated commingled completion inside 9-5/8-in. casing was implemented. The sand-face completion design consisted of a large-OD expandable sand screen with 150 micron weave across the 2 zones. Upon completion, the reservoirs were cleaned up through a temporary well clean-up and test facility to test productivity and evaluate integrity of the downhole sand-exclusion installation. Fines production, possibly due to a failure of the expandable screens, commenced almost immediately upon well bean-up and steadily increased to the extent that the well was deemed unproducible to the facilities.

The failure of the first well caused a re-evaluation of the sand exclusion method employed, which included more extensive core analysis and the completion types that would be suitable for development of the H1/H2 reservoirs. From this review, the operator and a service/ engineering company were able to develop a sand-exclusion method that combined several new technologies needed to effectively complete this reservoir.

To date, four wells have been completed with the new well configuration and sand-exclusion method chosen to address the completion needs. These have been tested, and to date, have proven to be operating satisfactorily.

This paper will review the evaluation that led to the sand-face completion design, the field implementation of the design, and the key installation success factors that were required. Results and a summary of best practices from the initial installations will also be summarized.
A Successful Pilot Application for N2 Foam Flooding in Liaohe Oilfield
Authors: Lin Yuqiu , Yang Guanglu
Published: December 2007

This paper presents a pilot application of N2 foam flooding in a heavy oil reservoir in Liaohe oilfield. After 9 years of steam huff-n-puff, the reservoir pressure is severely decreased, and several portions of the reservoir are unswept. It is urgent to find an alternative method of increasing oil recovery. Nitrogen foam flooding is proposed as a replacement EOR method. It diverts foam into the zones which were bypassed previously, increases the viscosity of the displacing fluid, and decreases oil viscosity.

The N2 foam flooding pilot was initiated in September, 1996 in Block JIN 90 in Liaohe oilfield. The average porosity of the reservoirs is 29.7%, and the crude oil viscosity at original formation conditions is 110-129 mPa.s. By the end of July 2004, 13 pilot patterns have been installed with 47 production wells and 13 injection wells. All the pilots have showed a favorable response till date – exhibiting improved sweeping efficiency, increased oil production, and increased reservoir pressure. They provide a valuable guideline for future development of N2 foam flooding in these reservoirs.
Reservoir Fluid Analysis Using PVT Express
Authors: Khan I. A. , McAndrews K. , Jose J. P. , Jamaluddin A. K. M. , Chetri H. B.
Published: December 2007

Representative reservoir fluid sampling & characterization has become increasingly important, as the exploration activities are moving into the ever-challenging environment around the world. Proper sampling and understanding of the fluid characteristics have become very critical, especially, when dealing with high-risk and marginally economic fields. With a timely and reliable characterization, unnecessary investments can be avoided. Unfortunately, with an unreliable characterization, an economic opportunity may not be pursued. Even worse, an un-economic opportunity may be pursued.

This seminar presents and discusses ways to capture representative reservoir fluid samples and a new fluid characterization technology that can be deployed on-site in the early stages of the exploration and development cycle. We demonstrate the applicability of new surface analysis techniques that allow for rapid, accurate, and reliable measurements of key fluid properties, such as saturation pressure, gas-oil ratio, extended carbon number composition, viscosity, and density, on-site within a few hours of retrieving representative reservoir fluid samples at surface. Consequently, prediction tools used to extend these limited measurements to a traditional "PVT" fluid characterization are also presented. In conclusion, it is shown that the implementation of the technique can reduce the risk associated with making key development decisions.
Solid Expandable Tubular Technology: Case Histories of Value-Adding and Enabling Applications in Sabah Deepwater Campaign
Authors: Miessner Daniel , Ochuko Erivwo , Wenting Wouter , Hopkins Chris , Nijveld Erik , Kaschke Markus
Published: December 2007

Solid expandable tubular technology has seen an impressive uptake in recent years. The technology has the potential to reduce cost, increase production and give access to new reserves. In 2004/2005, Shell Malaysia Exploration & Production installed solid expandables in seven wells, putting itself at the forefront of the technology and adding significant value to the business.

The design philosophy that has been adopted in Shell Malaysia can be described as:Use solid expandables as a planned-in contingency application in case the "trouble zone or event" is encountered. This approach allows for planning of aggressive well designs that fall back to expandables to mitigate problems.Use solid expandables in base-case casing design for deepwater wells with more than 5,000 to 6,000 ft below mud line and with four casing string design.

This paper describes four case histories of solid expandable tubular technology for the Sabah Deepwater exploration campaign in Malaysia. The technology was successfully applied and was very instrumental in achieving the well objectives and delivering a successful exploration campaign.

The key to this success was strong management support throughout the process. This took the form of creating an enabling environment to taking on board new technology and also by supporting actions to build up solid expandable tubular stock in the region to be able to quickly react to opportunities.

Technology support in Malaysia was provided through representation of Shell’s Global Implementation Team for solid expandables, making sure that global lessons were shared and best practices were applied. The Global Implementation Team also worked closely together with the technology provider on QA/QC and job planning aspects, which helped to keep a 100% success record with solid expandables tubulars for Shell in Malaysia.
State of the Art in Coalbed Methane Drilling Fluids
Authors: Baltoiu Len V. , Warren Brent K. , Natras Thanos A.
Published: December 2007

The production of methane from wet coalbeds is often associated with the production of significant amounts of water. While producing water is necessary in order to desorb the methane from the coal itself, the damage from the drilling fluids used is difficult to assess because the gas production follows weeks to months after the well is drilled. Commonly asked questions include: What are the important parameters for drilling an organic reservoir rock that is both the source and the trap for the methane? Has the drilling fluid affected the gas production? Are the cleats plugged? Does the "filtercake" have an impact on the flow of water and gas? Are stimulation techniques compatible with the drilling fluids used?

This paper describes the development of a unique drilling fluid to drill coalbed methane wells, with a special emphasis on horizontal applications. The fluid design incorporates products to match the delicate surface chemistry on the coal, a matting system to provide both borehole stability and minimize fluid losses to the cleats, and a BREAKER method of removing the matting system once drilling is completed.

Field results from three horizontal wells will be discussed, two of which were drilled with the new drilling fluid system. The wells have demonstrated exceptional stability in coal for lengths to 1000 m, controlled drilling rates and ease of running slotted liners. Methods for, and results of, placing the BREAKER in the horizontal wells are covered in depth.
Assisted History Matching for Surface Coupled Gas Reservoir Simulation
Authors: Biswas D.
Published: December 2007

For a gas reservoir, the intake pressures are available at a delivery point and the operator is obligated to supply gas honoring such downstream pressure requirements. As a result, it is imperative that the reservoir deliverability prediction be coupled with the pressure drop in the surface network. Additionally, this coupled system should not only honor the imposed delivery point pressure constraints but also the historical attributes of pressures and rates. In this paper, a modified Gauss-Newton method is utilized in conjunction with a non-linear parameter estimation algorithm to history match a surface-reservoir coupled gas reservoir simulation.

Control Volume Finite Element (CVFE) based reservoir simulator is amenable to unstructured grids to resolve near wellbore and high activity (high permeability channels, fractures) flow areas. The pressure drop in the surface network is modeled using Weymouth's equation of steady state pipeline flow. More importantly, the total system is solved in a coupled fashion thereby enabling the solution to be controlled by surface pressure constraints. In addition, both surface and reservoir decision variables are estimated using a modified Gauss Newton algorithm in the assisted history matching step.

Examples from dry gas reservoir demonstrate the usefulness of this methodology. First, the necessity of coupling surface and reservoir models is highlighted. Next, the computational efficiency of the assisted history matching algorithm as compared to perturbing critical reservoir and surface attributes in a heuristic manner is underscored.

There are three significant contributions of this paper, namely (a) an assisted history matching algorithm proves efficient in comparison to arbitrary perturbation of decision variables (b) a coupled reservoir-surface model renders a more accurate pressure prediction of the total system and finally, (c) an unstructured grid simulator provides the platform for accurate and cost-effective reservoir modeling alternative.
A New Strategy of Brownfield Development in New PT PERTAMINA EP Indonesia
Authors: Kurnely K. , Aprilian S. , Suarsana P.
Published: December 2007

There is big change in oil and gas industry environment since the oil and gas Law No. 22 of 20011 has been stipulated. PERTAMINA, was the only one state oil company, became a limited liability company called PT Pertamina (PERSERO). The exploration and production activities are under PT PERTAMINA EP, a subsidiary of PT PERTAMINA (PERSERO).

85% of the total production in PT PERTAMINA EP is from brownfield assets and total remaining reserve is more than 5 billion barrels oil. Those reserves spread out in 3 regions and 3 business unit areas. Most of the fields are located on shore, produced from primary recovery stage, and declined production around 20% per year.

To increase the national production from brownfield assets under a new management, PT PERTAMINA EP needs new strategies which can be applied in the future. Those strategies include: maximizing of value of the reserve audits which was done in December 2005, new business models in assets development, and managing the risk of new technology implementation.
Modeling of Large Hydrocarbon Compositional Gradient
Authors: Pedersen K. S. , Hjermstad H. P.
Published: December 2007

The paper presents fluid compositions sampled in 6 different depths in a North Sea petroleum reservoir over a vertical interval of 44 m. The fluid column consists of an upper gas condensate zone and a lower volatile oil zone connected by a gas-oil-contact (GOC). The data reveals large vertical variations in the fluid composition.

It is shown that the compositional variation with depth is much higher that what can be explained solely by the action of gravitational forces. The major contribution to the compositional variation originates from the influence of the vertical temperature gradient, which is of the order of 0.026 °C/m. The influence on the compositional gradient from the temperature variation is successfully described using the theory of irreversible thermodynamics.
Exploration Potential of Sinuous (Channellike) Events in Late Cretaceous of Al-Khafji Field, Middle East
Authors: Chakraborty Kalyan , Al-Hajeri Mubarak , Ray Jayanta
Published: December 2007

Stratigraphic trapping mechanism plays a critical role for hydrocarbon entrapment within the Middle-Late Cretaceous reservoirs in the Al-Khafji area. 3D seismic data are acquired aiming at to delineate the stratigraphic and possible strati-structural traps and their associated reservoir setting. Seismic attribute analysis of 350 sq. km. of 3D seismic data of Al-Khafji oil field shows number of sinuous (channel-like) events in the north and north-east of the main Khafji Structure in Tayarat Formation of Late Cretaceous age. The present study utilizes twenty two well data in the crestal part of the Khafji structure to generate a semi-regional facies log, which is turn up-scaled using seismic attribute map. As the area is not covered by any well or other form of data a variogram analysis followed by sequential indicator simulation method was used to derive a facies model between Tayarat and Bahra Formation of Lower Cretaceous age. A volume extraction method was used to extract channel events and integrate into the modeling process to visualize and track channels.

Present study infers a possible definition of facies inside sinuous events and their exploration potential. Porosity estimation using seismic attributes as well as borehole data provides most likely reservoir properties exist in shallow Tayarat Formation. The depth converted and extracted sinuous bodies along with possible porosity profile not only provide a rapid inside into the geology but also indicate further exploration potential particularly in the north-eastern part of the main Al-Khafji field.
A Multi-Scale Approach to Modeling Miscible Gas Injection Sweep Efficiency in a Giant Carbonate, Light-Oil Reservoir
Authors: Hui Mun-Hong (Robin) , Kamath Jairam , Dehghani Kaveh , Fischer Dennis
Published: December 2007

Modeling sweep efficiency of miscible gas injection into a giant carbonate, light-oil reservoir presents technological challenges at many scales, and requires an integrated study at the core, fine earth-model, and coarse flow-model scales.

We first perform phase-behavior studies and core-flood experiments to understand miscibility and sweep efficiency at the core scale. We conduct detailed reservoir-condition experiments on several core samples that are carefully selected to represent the important rock types of the reservoir.

A fine-scale geological model of the reservoir with about 2000 layers is then built. Factors that could impact sweep at the fine scale, such as the Todd-Longstaff mixing parameter and vertical-to-horizontal permeability ratio, are investigated.

A flow-based, nonuniform approach is used to coarsen the fine-grid models by a factor of thirty. The upscaled absolute permeabilities (k*) are computed for the coarse models. We then generate upscaled relative permeability curves (krj*) and bypassed oil saturation (Sorb) values for the upscaled flow grid, and these are used in a modified Todd-Longstaff (TL) miscible simulator. Traditional TL models use straight-line relative-permeability curves (since oil and gas are first-contact miscible) and do not address the need for krj* as a result of upscaling. We apply a novel miscible upscaling technique to generate krj* and Sorb for the coarse-scale models. In our upscaling, we investigate factors such as boundary conditions, inter-well spacing, and the form of the relative-permeability curves to ensure that our assumptions are appropriate for the field problem. By performing scale-up validation studies on sector models, we demonstrate that our overall upscaling approach yields accurate flow results.

The coarse-scale full-field simulation models generated through our upscaling are employed in making predictions crucial to project-planning, economic evaluation as well as to determine the optimal miscible-flooding strategy through sensitivity studies.
Implementing a Framework for Knowledge Management
Authors: Gibby P. J. , Milton N. , Palen W. A. , Hensley S. E.
Published: December 2007

Corporate knowledge is the asset enabling an organization to take effective action, and make crucial decisions correctly. A key challenge for business leaders is how to engage everyone in the processes of knowledge capture, sharing and application. Increasingly, the notion of an internal knowledge economy is becoming a reality for many companies as they strive to become distinctive from the competition.

People and human behavior are at the core of KM. Robust approaches to leverage the collective knowledge of an organization must be adopted entity-wide in order to affect high standards of capture, transfer and application. If KM is to be successful, the organization must be given a clear framework to guide, support, monitor and continuously improve the integration of collective know-how in pursuit of specific business goals.

This paper describes a framework for managing knowledge, which is becoming increasingly adopted within BP's Exploration & Production (E&P) business segment. The Major Projects Knowledge Framework addresses the governance of knowledge as well as the support elements (people, process and technology) necessary to ensure knowledge is applied as needed, when needed and in a format that is usable by others.
Service the Limit—Operational Excellence in Well Intervention
Authors: Anyanti Sylvester C. , Hopmans Paul A.
Published: December 2007

Well Intervention cost makes up a major part of the total operating expenditure in Shell EP Asia. The belief that well service operations are constrained to original well design and little could be done in the area of service optimization has made not a few to miss the opportunity of delivering operational excellence.

Service the Limit (STL) is an offspring of the Drilling the Limit* (DTL) methodology, widely applied by Shell Well Delivery teams. Until recently, this structured approach to value creation and realization existed only in drilling operations. STL is about replicating the DTL practices while servicing completed wells.

The DTL methodology and its application to drilling have previously been described in great detail; the intent of this paper is to highlight the experience of applying this methodology to well intervention planning and execution.

STL was introduced to Shell EP Asia (Malaysia and Brunei) in late 2003, with initial focus on training of champions and optimizing the execution phase of well service operations. This led to over 10% cost reduction. The quick-win encouraged a replication of the methodology in other parts of the region, with added focus on front-end activity loading, alignment to Shell EP Global Well Delivery Process and its integration with other hydrocarbon maturation processes.

It is recognized that irrespective of the versatility of a process, the primary activities, carried out by real people is what makes most of the difference in performance. STL is a systemic tool designed to support the people; it is an improvement to the isolated or once-in-a-while well intervention program optimization reviews. Uptake of this methodology will help the EP organizations to better face challenges ahead, especially in deepwater environments.

This paper will cover implementation of STL methodology, associated activities, results and future sustenance plan.
Optimization Process Extends Application of PDC Bits to Reduce Cost in Major Russian Fields
Authors: Jidkov Alexander , Zalogin Boris , Pritchard Wyatt , Dmitruk Sergei , Byvald Edward , Gaifullin Farid
Published: December 2007

In the harsh drilling environments of Siberia where logistics are difficult and expensive, a process of design optimization has led to successful application of PDC bits in the intermediate hole section of development wells, reducing costs and resulting in a record footage performance of 13944 meters – and counting – by a single 11-5/8" PDC bit.

To control costs in the remote Ust-Vakh area of the Samotlor Field of Siberia, bits and equipment must perform at an optimum level. Typically drilled using roller cone bits and turbine motors, the application requires sufficiently rugged equipment to efficiently drill sand/shale formations without costly and time-consuming trips for repair or replacement.

This paper describes the practical evolution from use of roller cone bits and turbine motors in the intermediate hole section of these wells, to use of fixed cutter PDC bits and positive displacement motors (PDMs). The resulting performance improvements are documented, including a world footage record of 13944 meters. To facilitate rapid deployment of application-specific bit technology despite the remote location, an in-house bit specialist was located at the field operations base, collaborating with the drilling department in implementing the optimization process. Focusing on the intermediate hole section from approximately 430m to 1100m depth, areas of potential improvement were identified, and solutions proposed.

Based on success in similar applications, fixed cutter bits were recommended that incorporated steel body designs with advanced hydraulics, while analysis of various bit/BHA combinations identified the most efficient configurations for this application.

Ultimately, large diameter roller cone bits with an expected life of one or two runs were replaced by steel body PDC bits that have been re-run as many as a 20 times or more, with average days per drilling in intermediate section reduced from five to just four days.

The paper summarizes savings realized, and describes additional design changes now under investigation.