bluuebunny/crossref_metadata_2025 huggingface dataset:
Viscous-Pill Design Methodology Leads to Increased Cement Plug Success Rates; Application and Case Studies from Southern Algeria
Authors: Fosso S. Wamba , Sonatrach M. Tina , Frigaard I. A. , Crawshaw J. P.
Published: December 2007

Setting heavy cement plugs on top of lighter wellbore fluids is a major problem in Southern Algeria, for both drilling and work-over wells. When setting cement plugs off-bottom, for kick-off or abandonment, an average of 3 attempts are necessary before achieving a competent cement plug. The extra cost of the failed plug operations is around $75,000, plus 4 days of lost rig time. An in-depth analysis of field practices for cement plugs demonstrated that the root cause of the failures is related to poor or non-existent design of the viscous pill rheology. In effect, until recently, the viscous pill was made the same way, regardless of the cement properties and of the cement-viscous pill interface stability.

There is a natural tendency for a heavy fluid to fall through a lighter fluid placed below it and it is only by resisting this tendency that cement plugs, set off-bottom, are able to remain static until the cement hardens. The larger the difference in fluid densities or the larger the size of hole, the harder it becomes to stabilize a heavy plug.

Commonly, a viscous-pill is set between the cement slurry and drilling mud, in order to improve stability. Recent work, both theoretical and experimental, has determined a reliable estimate of the yield stresses required of the fluids to stabilize an interface separating heavy and light fluids, under any conditions of hole size, deviation and density difference between the fluids. When a viscous pill is used two interfaces: that between the cement slurry and viscous pill and that between the viscous pill and mud, could be unstable. The estimates have been turned into a computer model that can be used to design the physical properties of both viscous pill and cement slurry, so that mechanical stability is ensured.

Application of this model to cement plugging operations in Southern Algeria has given rheology and density design targets, which have been applied to both cement slurry and viscous pill. Three case studies are presented in which the top of cement was found exactly as expected, on the first plug set. Over a number of recent cement plug jobs, the success rate has improved from ~25% to close to 100%.
Performance Improvement Techniques Used on Goodwyn A Platform
Authors: Dolan S. P. , Barrows W. J. , Dickson J. W. , Torry D. , Drury R. F.
Published: December 2007

This paper is a review of the techniques that have caused a large improvement in drilling and completion performance on the Goodwyn A Platform North-West Shelf, Australia. The collective effort of Well Construction professionals using these techniques has resulted in the drilling of a 6263m (20,550’) TD well with a horizontal step out of 5200m (17,060’), at a tangent angle of 67° in 39 days from spud to well handover. This was 31% under P50 AFE time estimate.

The paper will describe a method to produce systematic, steady and sustainable improvements to Well Construction operations. The methods described are a way of harnessing the collective brainpower of Well Construction professionals and focus that energy towards rigorous analysis of problems or areas of potential improvement, then systematically working through and implementing solutions.

The Technical Limit methodology and Performance Improvement Groups (PIGs) are best suited for complex, high cost drilling projects, typically ERD developments, high cost MODU exploration or subsea operations.

In addition, other tools such as Hazard Management, Learning System and Planning Processes which contributed to success are explained.
Development of Stable PDC Bits for Specific Use on Rotary Steerable Systems
Authors: Barton S.
Published: December 2007

The number of extended lateral reach and horizontal wells have been increasing due to resulting economic benefits. The steerable motor is accepted as the standard method of directional drilling but is not ideal for these sections. As a result, rotary steerable systems have been developed and benefit over motors due to continuous pipe rotation whilst deviating. This results in a smoother, cleaner hole and less drag, leading to improved transfer of weight and increased penetration rates.

This technological development has prompted the design of a range of PDC bits specifically for use on rotary steerable systems. Namely, that they possess sufficient lateral cutting ability to successfully perform in highly deviated sections at the reduced rotational speed, as compared to that of conventional motors. The designs must also be stable in rotation to minimise downhole vibrations that could damage the bit or cause premature tool failure.

Through progressive design and continuous field performance analysis, specific bit features have consistently displayed good steerability and very low levels of vibration, without compromising drilling performance.

Detailed analysis has been conducted using vibrational logs and data downloaded from a rotary steerable tool over a multitude of field runs. Overall bit performance was compared between similar designs with differing cutter placement.

Combined results demonstrate that a specific cutter placement methodology is essential for successful bit performance on a rotary steerable tool in terms of both stability and directional capabilities, and has resulted in extended bit life. Design considerations are laid out with regard to lateral cutting ability in terms of profile and cutter placement.

Case studies on field performance illustrate the design progress in producing a steerable, stable bit for use with a rotary steerable system.
Marginal Expense Oil Well Wireless Monitoring
Authors: Nelson Donald G.
Published: December 2007

Wireless surveillance of rod pumped oil wells has typically involved mating high power radios with pump off controllers. These combinations are very effective but economic application is limited due to cost. A need exists for a simpler wireless surveillance system that can be economically applied to stripper wells. Continued breakthroughs in the technology sector have lead to lowered cost and improved quality for a variety of electronic components. This study involves a low cost, small, self-contained wireless vibration surveillance unit that can be bolted directly to the pumping unit. The device includes a shear-sensing transducer, battery, pre-programmed microchip, and low power radio transmitter. Signals related to the vibration behavior of the pumping unit are transmitted to a base station computer that will indicate an alarm condition when the well deviates from normal, pumped off performance.
Improvements to Reservoir Material Balance Methods
Authors: Pletcher J. L.
Published: December 2007

Experience with a number of material balance data sets from the field and from simulation has revealed some procedures that can be used to improve analysis of both oil and gas reservoirs: Failure to account for a weak water drive can result in material balance errors that are not insignificant.The assertion of previous authors that a weak water drive exhibits a negative slope on the Cole Plot (gas) and Campbell Plot (oil) has been confirmed. A weak water drive is detected on these plots much more unambiguously than on other common plots such as the p/z plot for gas.A Modified version of the Cole Plot is proposed to account for formation compressibility.The reservoir drive indices are a useful tool for determining the correctness of the material balance solution because they must sum to 1.0. The drive indices should never be normalized to sum to 1.0 because this obscures their usefulness and leads to a false sense of security.A modified version of the Roach Plot (for gas) is proposed that improves interpretation in some water drive situations.Material balance has not been replaced by reservoir simulation, rather it is complementary to simulation and can provide valuable insights to reservoir performance that cannot be obtained by simulation.
Worldwide Crude Oil Production Capacity, Supply, and Demand: What is Your Baseline?
Authors: Jentsch W. A. , Merryman A. A. , Littell G. S. , Groppe H.
Published: December 2007

Reasonably accurate information of worldwide crude oil production capacity, supply and demand (CSD) is crucial to management and investment decisions in the energy industry in particular and the economy in the aggregate. As the industry relies on consistently flawed reporting processes, the industry encounters dynamics outside those normally experienced in a commodity industry.

The International Energy Agency (IEA) is the primary source of the public data. The IEA was created in 1974 as the response to the 1973 Arab oil embargo of 16 member countries of the Organization for Economic Cooperation and Development (OECD). This paper will help the reader to understand the IEA's organization and some of the inaccuracies inherent in the reporting processes. This understanding should assist those using the data to develop better forecasts and should be of interest to those seeking to improve the reporting process.

Coupled with this investigation will be a brief glance at the historical worldwide crude oil supply, capacity and demand and the corresponding price trends. The reader will gain a tool for enhancing their strategic planning in addition to increasing the accuracy of price forecasts by seeing the relationships between recent price trends and the IEA reports of capacity, supply and demand,
Relative Permeability Measurements for Post-Waterflood Depressurisation of the Miller Field, North Sea
Authors: Naylor Peter , Fishlock Terrence , Mogford David , Smith Robert
Published: December 2007

This paper describes a determination of critical gas saturations and relative permeabilities relevant to the depressurisation of the Miller field. A series of reservoir condition coreflood experiments and associated numerical simulations is described. Three experiments were conducted with aged Miller core and fluids at 120°C and each comprised of a waterflood at about 414 barg, followed by depressurisation at different rates. The laboratory data included extensive three-phase in-situ saturation measurements which were used to derive gas relative permeabilities through the simulations.

The rate dependent critical gas saturations varied between 0.06 and 0.21 and gas relative permeabilities of the order of 0.0001 were deduced. These laboratory results are consistent with published data and demonstrate that conventional Corey-type gas relative permeabilities are an order of magnitude too large and do not represent the depressurisation process.

This paper is believed to be the first publication of: A reservoir condition study of the depressurisation of aged, waterflooded cores.Extensive, reservoir condition, three-phase in-situ saturation measurements which enable critical gas saturations and gas relative permeabilities to be determined.A slow depressurisation experiment with a duration of 141 days.

Mobilisation of gas in Miller has been found to have a significant impact on oil production profiles and project economics, and the data from this study can be used to reduce the risk associated with depressurisation.
Directional Surveying: Rotating and Sliding Operations Give Different Wellbore Position Accuracy
Authors: Torkildsen Torgeir , Bang Jon
Published: December 2007

We present a novel method for analysing the position uncertainty of directional surveys. By this method, the uncertainty can be accurately calculated by conceptually simple analytical formulae. The theory covers any correlation in measurement error and any correlation in toolface, for both stationary and continuous surveys.

The results demonstrate the importance of handling the toolface dependence properly. A direct benefit is that too optimistic or overly pessimistic accuracy estimates are avoided. Furthermore, the difference between rotating and sliding operation is significant for many error terms. For example, a misalignment error typically causes 10 times higher position uncertainty in sliding mode than in rotating mode, for a 3000 m long survey.

These findings should have implications for the future specification of survey instrument operation procedures, and thus the design of directional survey programs.
Asia Pacific Colloquium on Petroleum Engineering Education 1999
Authors: Pinczewski W. V. , Akbar Tajudin Abdul Wahab Tuan Hj.
Published: December 2007

This paper provides a summary of the discussions and major outcomes of the 1999 SPE Asia Pacific Colloquium on Petroleum Engineering Education (17–20 October 1999 in Langkawi, Malaysia). The colloquium attracted a total of 49 delegates from 13 countries and was held in the context of continuing rationalization and downsizing in industry and a general economic downturn in Asia.

The colloquium proved to be a valuable forum for constructive Industry – University dialogue. A wide range of issues was discussed, some generic and some specific to the Asia Pacific region. There was clear recognition that PE courses will need change to become more responsive to changing industry needs and conditions.
Predicting Connected Hydrocarbon Volume Uncertainty Ranges: From Static Fault Model to Dynamic Simulator
Authors: Ainsworth R. B. , Stephenson P. M. , Johnson D. A. , Seggie R. J.
Published: December 2007

In this paper we present two methods for calculating uncertainty ranges for connected hydrocarbon volumes as applied to the Sunrise gas-condensate field, Timor Sea. A "quick look" approach which uses a simplified, exploration scale fault data set.A more detailed fault interpretation which is integrated with 3-D geological and dynamic reservoir modelling techniques.

Despite the differences in sophistication, the two methodologies generate similar results in terms of absolute connected hydrocarbon volume ranges.

In both studies the fractal relationships between the fault throws, lengths and frequency of occurrence were used to determine the minimum throw of faults fully interpreted on the seismic. This structural interpretation was then augmented by the probabilistic infill of sub-seismic faults with throws greater than the critical juxtaposition-sealing throw of 20 m. The resulting maps were then used to estimate a range of potentially connected gas volumes.

The large number of across fault sand-sand juxtapositions within the areally extensive field suggests that as a most likely case the reservoir is 100% connected due to effective communication across faults or around fault tips. Sensitivities were analysed around this most likely case. As a worst case scenario all faults were assumed to be totally sealing due to the potential effects of shale gouge or cataclasis. The quick look study, which took no account of any sedimentological connectivity issues, predicted a worst case connectivity of 77% whilst the detailed 3-D dynamic simulator study predicted a connectivity of 72%.

Although the areal distribution of connected hydrocarbons was different for the two approaches, the similarity of the final connected volume figures suggests that the quick look methodology provides a useful technique for the rapid estimation of connected hydrocarbon volume ranges in fields with limited data content and perceived simple sandbody architectures.
Well Planning Under Uncertainty: Application of a Systematic Procedure for Risk Assessment and Uncertainty Analysis for New Well Targets on the Brage Field
Authors: Hersvik Karl J. , Aanonsen Sigurd I. , Petersen Lasse S. , Fjellbirkeland Hege , Robson Adrian , Sperre Thomas
Published: December 2007

The Norwegian North Sea Brage field came on production in Sept. 1993. The field is currently producing approx. 8000Sm3/d and is on steep decline from its plateau rate of 19400Sm3/d.

In March 1999 it was decided to stop the drilling for approximately one year. During this year new reservoir models were built and history matched. Although this work proved to be both complicated and tedious it was fairly successful. However there was still a high degree of uncertainty in the understanding of the flow pattern and the pressure behaviour of the field. It was therefore decided to perform a comprehensive uncertainty analysis to get better estimates of the expected production and risk related to a resumed drilling. The analysis was performed both on a well to well basis and combined into a drilling campaign.

The paper will describe analysis in detail illustrated with field examples.

A reservoir simulator is utilized to estimate the unconstrained well potential for each well. Then total field water handling constraints is imposed using a tool that optimizes the production given the individual well profiles and the platform constraints. This gives a basis for determining the base case Present Value, PV, for each well's contribution to the field production. For each well target, the most important uncertainties with corresponding probability distributions are identified, and their effect on the PV determined by simulations. In cases where the simulation model is judged not to represent the reservoir behaviour correctly, analytical methods are used. Finally, these results are used together with the drilling cost into a Monte Carlo simulation loop to determine probability distributions for the NPV of each well and for the total drilling program.

It is shown that even though most of the individual well targets has a high risk of a negative NPV, the economy of the total drilling program is robust and has a significant upside economical potential.

The procedure, which is based on commercially available software only, has proven to be very flexible. It is easy to incorporate new uncertainties related to a well target, or to include or exclude a well target from the drilling schedule. Finally, the resulting NPV probability distributions provide an easy way of ranking well targets based on expected NPV and risk.
Hydrocarbon Field Planning Tool for Medium to Long Term Production Forecasting from Oil and Gas Fields Using Integrated Subsurface - Surface Models
Authors: Beliakova N. , van Berkel J. T. , Kulawski G. J. , Schulte A. M. , Weisenborn A. J.
Published: December 2007

The Hydrocarbon Field Planning Tool (HFPT), recently developed by Shell, provides capabilities for rigorous integrated subsurface-surface production forecasting in the medium to long term (1-30 years). HFPT can be used for gas, gas-condensate, oil and mixed gas-oil fields. HFPT models allow business optimisation by making more efficient use of the existing assets and by reducing investment costs in the new fields.

In the simulation, HFPT uses a pressure-balanced solution of the integrated system: from the reservoir(s), through wells and surface facilities, to the delivery point. A wide range of fluid models is available, from simple gas-condensate and black oil PVT models to multi-component models with EOS flash calculations. HFPT provides optimisation functionality for maximising the returns in oil and gas fields, while accommodating operational preferences for production allocation and network constraints. It can also model injection networks and optimal lift gas distribution.
Geo-Oriented Horizontal Drilling in the Rotliegend – A Learning Experience
Authors: Werngren Oonagh
Published: December 2007

This paper describes the successful application of geo-oriented LWD technology to the precision drilling of 4 horizontal reservoir sections in complex Rotliegend wells in the UK Southern North Sea (SNS). Detailed planning, teamwork and acquisition of real-time data enabled the sub-surface team to drill the wells efficiently, applying continuous improvements to the geo-orienting technique through an inherent feedback and learning process. As a result, a significant reduction in cost/foot was achieved throughout the campaign. One of the field developments was subsequently benchmarked as a Best In Class project by the 1999 IPA benchmarking report.
Early Production Systems (EPS) in Ultra Deep Water, a Way to Improve Reservoir Management and Field Economics
Authors: Valenchon C. P. , Anrès S. J. , Baudouin B. F. , Biolley F. M.
Published: December 2007

Offshore developments in ultra deep waters will lead to huge investments, therefore their profitability will have to be assessed as thoroughly as possible prior to sanction.

One way to reduce reservoir risks is to use early production systems (EPS). They are cheaper to build, reduce time to first oil, and provide a better knowledge of the reservoir after one or two years of production.

Some conventional EPS solutions can be extrapolated to deep and ultra deep waters, but the cost of risers and mooring lines for such systems might become prohibitive and alternate solutions could become more economical with increasing water depth.

West Africa presents a unique situation with a large number of discoveries in deep waters as well as many prospects in ultra deep waters, combined with exceptionally mild metocean conditions.

After the review of some existing shallow and deep water EPS schemes, followed by a description of the main EPS technical and economic drivers, the paper will present the potential for such systems and the technical challenges associated with their use in West African ultra deep water.

Finally an innovative EPS solution is proposed, involving the use of a modified tanker outfitted with a central moonpool housing vertical, top-tensioned risers with surface trees.

This solution is an autonomous EPS system offering new possibilities to enhance well production tests and reservoir monitoring.
Reservoir Modeling for Giant Romashkino Field (Problems and Solutions)
Authors: Abdulmazitov R. G. , Blinov A. F. , Dikov V. I. , Ibatullin R. R. , Latifullin F. M. , Khisamov R. S.
Published: December 2007

History of giant Romashkino field exploration and development includes more than 50 years. Huge information bases on its geologic structure and exploitation is accumulated by now.

The field presents asymmetric uplift of areal extent about 100 × 100 km. Commercial oil inflows have been obtained from 18 horizons. Some differences in formation fluid characteristics are observed throughout the field. By present the field is divided into 21 independently developed areas. Initial division of structures was made under conditions of insufficient information and was adjusted later. In connection with uncertainty in geologic structure there might be crossflows between structures of contour division. These conditions make difficult modeling and monitoring of the whole field development.

For conductance of geologic and hydrodynamic modeling we have determined the following main principles:

structure-by-structure modeling of the field, uniform procedure principles for all being modeled structures, parallel modeling of main field elements – areas.

At present 3D geologic and hydrodynamic models for 5 areas of Romashkino field are developed and used. This is more than 6000 wells. 3D models are being brought now into commercial operation, i.e. realization of idea for continuously operating models of areas, blocks and experimental sections. This is practically possible based on fiber-optics system of communication applied in the field, which ensures interaction of all company structures. This will enable to provide application of efficient technologies and software for solution of applied tasks to most number of users.

Uniform monitoring of the whole field development as a complex of all areas will be provided upon completion of hydrodynamic modeling of all areas.
Rejuvenating Production in Brown Fields with Horizontal Sidetracks
Authors: Ogoke Victor C. , Akhideno Matthias , Akinkunmi Akin , Nwosu Chike , Ugboaja Remmy , Simon Roya , Matemilola Saka
Published: December 2007

Horizontal sidetracks offer a very viable technique for rejuvenating production in the redevelopment of brown fields. In brown fields where significant reserves exist, but occur as scattered pockets of by-passed oil, or in stacked reservoirs, their development with new wells will hardly satisfy economic screening criteria. The abundance of old wells that have drained the recoverable reserves in their drainage area and are either producing at very low rates or are closed-in, make horizontal sidetracks a viable tool for rejuvenating production and maximising existing assets.

With a vision to improve production in SPDC by 60% in 2004 and by over 200% (to 2.5 MMbopd) in the year 2010, producing the limit or sweating the existing brown fields is now a key factor. Most new wells are now horizontal completions, due to their higher productivity over vertical or inclined wells. This paper presents the benefits of horizontal sidetracks as a productivity improvement tool that was used to boost production from Obigbo North (one of SPDC-E brown fields) by more than 10,000 BOPD in 1999 alone. It discusses production gains, geology, well construction, completion types, environmental benefits and petrophysical data acquisition and interpretation problems that could be encountered with horizontal sidetracks in brown fields, based on our experience.
Horizontal Well Performances in Hassi-Messaoud Oil Field, Algeria.
Authors: Azzouguen A. , Mazouzi A. , Delhomme A. , Deghmoum A.
Published: December 2007

The objective of this study is to analyze the performance of non-conventional wells drilled in Hassi-Messaoud field, Algeria. A new technique "Direct Synthesis" developed by Dr. D. Tiab1, 2 is used for the pressure transient analysis. It permits the determination of permeability tensor as well as the effective length of the horizontal well. Hence, and for the first time, the permeability tensor (Kx, Ky, Kz), and the vertical permeability anisotropy (Kv/Kh) were obtained. The results of the interpretations lead to a verity of information and correlations. Sensitivity studies allow the optimization of future horizontal drilling plannings.

The comparison between the performances of slanted, horizontal, and multilateral wells shows that slanted wells, regarding the low risk, are the most appropriate for Hassi-Messaoud field. From the spatial distribution of permeabilities, Kx, Ky, Kz, important conclusions are illustrated regarding the geological model of the field.

Horizontal wells are not only beneficial for improving productivity but also for the tremendous amount of information they provide. Form this study several recommendations are issued regarding the well spacing taking into account different geological models.
Wellbore Stability Simulations for Underbalanced Drilling Operations in Highly Depleted Reservoirs
Authors: Parra J. G. , Celis E. , De Gennaro S.
Published: December 2007

The need to increase productivity reducing drilling formation damage favours the use of underbalanced drilling technology. The main idea is to drill with equivalent circulating densities (ECD) below the formation pore pressure and to avoid the contact between the drilling fluid and the formation. In highly depleted reservoirs, pore pressures can be very low. Therefore, extremely low density fluids such as foams are used to achieve circulating densities below pore pressure. In such cases, the induced modification of the in situ stresses has to be supported mainly by the rock, with low contribution of the drilling fluid pressure. In that sense, the application of underbalanced drilling depends, among other factors, on the mechanical stability of the drilled formation. In general, poorly consolidated depleted formations are not suited for that technology. This paper presents the wellbore stability simulation performed in order to establish the feasibility of using underbalanced drilling in highly depleted reservoirs in western Venezuela. The in situ stress field and the mechanical properties of the formation were obtained. Pore pressure as low as 800 psi at 5500 ft (2.7 lb/gal equivalent fluid density) was measured. The finite difference method and an elastoplastic constitutive model was used to obtain the new stress, deformation and pore pressure distribution. The undrained condition (immediately after the wellbore is drilled) as well as the drained condition were analysed. The analysis showed that horizontal wells could be drilled in an underbalanced condition with low instability risk. Following the recommendations, four horizontal wells were drilled in underbalanced conditions. Values as low as 2.0 lb/gal ECD were used to drill the wells and no wellbore instability problems were reported. Production tests showed an enormous increment in well productivity index in comparison with conventional overbalanced drilling.
Borehole Acoustic Reflection Survey Experiments in Horizontal Wells for Accurate Well Positioning
Authors: Yamamoto H. , Watanabe S. , Koelman J. M. V. , Geel J. , Brie A. , Fujii K. , Coates R.
Published: December 2007

Reservoir management optimization requires a detailed description of the geometry and the properties of the reservoir. For horizontal wells, knowing accurately the position of the borehole in the reservoir is critical. However, seismic techniques do not have sufficient resolution to provide the position of the well with respect to the reservoir boundaries with desired accuracy. Sonic measurement on the other hand has the potential to provide such information. We conducted experiments in horizontal wells in Oman using a commercial multi-receiver sonic tool modified for imaging, with extended spacing between the transmitter and the receivers. Although the tool characteristics are not optimized for the imaging, we obtained interesting results when the reflectors have sufficient strength, thus showing the potential of this technique. The pre-processed and migrated sonic images provided useful information on the geometry of the reservoir, which could be compared with seismic interpretation and field knowledge. Furthermore, we developed a specific processing technique that uses the four different waveforms acquired around the tool at each receiver station to separate the reflections coming from above the well and the ones coming from below. In this way, we could obtain images that could be interpreted more easily. In some instances, the position of the reservoir boundaries could be determined with an accuracy of 1 m up to a maximum distance of 10 m.
Analysis of Fracture-Matrix Fluid Flow Interactions Using X-Ray CT
Authors: Alajmi A. F. , Grader A. S.
Published: December 2007

Multi-phase fluid flow in fractured rocks is essential for maintaining and enhancing oil and gas recovery. The fluid flow interaction between the fractures and the matrix has a significant impact on displacement processes. This paper presents two-phase flow displacements in layered Berea samples that have been artificially fractured. Two experiments were conducted in this work. In one experiment, the fracture was induced at the inlet end of the core allowing us to study diverging flow, and in the second experiment, the fracture was induced at the outlet end permitting us to study converging flow. The temporal and spatial saturation distributions of the two cases were determined using x-ray computerized tomography (CT).

The presence of the fracture delayed the recovery processes and significantly reduced the breakthrough time. Three different fluid flow behaviors were observed at three regions in the sample, the fracture region, at the tip of the fracture, and at the non-fractured region. At the tip of the fracture, the two experiments showed different fluid flow patterns. The displacement process in the fractured region was a two-dimensional process with a strong vertical flow component in the high permeability/porosity layers. The displacement contrast between the layers was more pronounced in the fractured region than in the non-fractured region. The low permeability/porosity layers had high saturation of the displaced fluid even at late time. Oil recovery from waterflooding was delayed due to fluid bypassing caused by the fracture.
A Modified Equation of State for Gas-Condensate Systems
Authors: Erdogmus M. , Adewumi M. A.
Published: December 2007

Accurate prediction of thermophysical properties is an essential requirement for optimum design and operation of most process equipment involved in petroleum production, transportation, and processing. Equipment failure is often directly attributed to lack of accurate design data. Methods of fluid property prediction can be divided into three main categories, namely the Corresponding States Theory (CST), Equation of State (EOS) model, and Activity Coefficient Model (ACM). The EOS approach is most popularly used for natural gas systems due to its applicability at high pressures for both liquid and vapor phases.

Probably the most successful cubic equation of state for natural gas property calculation is the one proposed by Peng and Robinson (PR)1. However, Peng-Robinson EOS assumes a fixed value of critical compressibility factor and, as a result, the predicted densities of the saturated liquids and the predicted critical volumes differ considerably from experimental values. Patel and Teja (PT)2 introduced a substance dependent critical compressibility factor that allowed them to more accurately reproduce the experimental saturated liquid volume at a particular temperature.

The present work is an extension of that of Patel and Teja. The modified Patel and Teja’s EOS improves the prediction of liquid phase density and vapor liquid equilibrium. A comprehensive assessment of the modified equation-of-state is conducted through performance comparison with the more popular equations of state. For saturated liquid volume predictions, the improved equation of state yields 33% and 11% improvement over PR and PT EOS, respectively. For vaporization equilibrium ratio predictions, 36% improvement over PR and 67% improvement over PT EOS are observed.
Modeling Flow in Geometrically Complex Reservoirs Using Hexahedral Multi-Block Grids
Authors: Jenny Patrick , Wolfsteiner Christian , Lee Seong H. , Durlofsky Louis J.
Published: December 2007

A hexahedral multi-block grid formulation for the modeling of two phase reservoir flows is developed and applied. Multi-block approaches are well suited to the modeling of geometrically complex features while avoiding many of the complications of fully unstructured techniques. Important implementation issues, including the accurate treatment of grid non-orthogonality and full tensor permeability (through use of a 27-point finite difference stencil), the treatment of exceptional cases arising when five blocks intersect, and a new well model which allows for the accurate resolution of near-well effects, are discussed. Solution efficiency issues, including the use of tensor splitting and the linear solution technique, are also discussed. The actual grid generation step is accomplished using a commercial package. Results for a variety of cases, involving flow through geologically complex systems and reservoirs with horizontal and deviated wells, are presented. Comparison with analytical results demonstrates the high level of accuracy of the 27-point formulation and the new well model. The method is also applied to a realistic example involving flow through a heterogeneous faulted system. This example illustrates the types of geometrically complex systems that can be modeled using the hexahedral multi-block approach.
Upscaling of Two-Phase Relative Permeability in Heterogeneous Porous Media
Authors: Rodriguez A. A. , Araujo M.
Published: December 2007

In this work we present some recent developments related to the simulation of two-phase flow in porous media. It is shown here, a new formulation to solve the two-phase flow problem based on the use of renormalization techniques on hierarchical lattices. This method allows us to perform simulations about 1000 times faster than those obtained using conventional methods. In this work we have used an eight-shape lattice on which we have discretized the flow equations including the effect of capillary pressure. Our findings show that for the homogeneous case, the results are almost exact compared to the results obtained using the usual methods. In other results, we prove that the oil residual saturation and relative permeability curves have a strong dependence on the size and disorder of the system.
Gaseous Emission Monitoring in the Land Area of the Western Niger Delta
Authors: Ozumba C. I.
Published: December 2007

The Shell Petroleum Development Company as part of her environmental management programme monitors gaseous emissions in its flare sites located all over the Niger Delta basin. This paper details the findings of this programme in a full year of monitoring in the Land Asset Area of the Western Niger Delta. The parameters measured include, heat radiation, soil temperature, noise levels, smoke density, air turbulence, wind speed/direction, air quality (Sox, Nox, Total Suspended Particulate matter, and other volatile organic compounds) and physico-chemical parameters of rain water. These parameters are monitored at various distances from the flare site point source. Results show that all these parameters are currently well below the limits accepted by the World Health Organisation, the Department of Petroleum Resources in Nigeria and the Federal Environmental Protection Agency – FEPA (now Federal ministry Of Environment – FMENV).
An Evaluation of the Department of Energy Naval Petroleum Reserve No. 3 Produced Water Bio-Treatment Facility
Authors: Myers James E. , Jackson Lorri M. , Bernier Rene F. , Miles David A.
Published: December 2007

The Department of Energy (DOE) Naval Petroleum Reserve No. 3 (NPR-3) produced water bio-treatment facility effectively treats an average of 35,000 barrels of water per day. All discharge limits are met. The functional component parts of the bio-treatment facility consist of cooling, blending, oil/water separation and biological treatment. The bio-treatment facility replaced subsurface injection saving $175,000 per year on utilities ($3.5MM over the 20-year life expectancy). The surface discharge of the treated produced water benefits wildlife by keeping a normally dry streambed wet year-round with an abundance of wetland plants for forage.

This bio-treatment facility evaluation is based on site observations over the past four years, review of historical discharge data and a one-time sampling event at eight locations within the facility in September of 1999. The suite of analytical tests include BOD5, COD, TOC, TIC, TPH, O&G, GRO, DRO, BTEX, Ca, Mg, SO4, TKN, NH3, NO3, Alkalinity, pH, EC, hardness, H2S, P (total), PO4 (ortho), TDS, TSS, turbidity and VS. In addition, selected temperature and flow measurements were collected. Hach Biological Activity Reaction Tests (BARTs) were used to measure microbial activity in the water and soil columns and to demonstrate the "substrate effect." The sampling event occurred shortly after an upset event that resulted in a hydraulic surge, elevated temperatures and skimming difficulties. In spite of the upset, the bio-treatment facility's removal rates were >90% for nearly all analytes. The extent of hydrocarbon removal ranged from 95% to 100%.

The areas identified for potential improvement to the bio-treatment facility include cooling capacity, solids handling/removal, skimming operations, flow control and water control structures, replanting of the wetland (free-water surface and/or subsurface), future discharge limits and water reuse.
Treatment Of Drill Cuttings
Authors: El-sayed Abdullah , El-Naga Kamal H. Abu
Published: December 2007

The environmental impact of oil and gas well drilling is a major issue facing today's petroleum industry.

One of the most difficult environmental problems to resolve at the well site is the disposal of waste mud and cuttings they are often physically unstable and unsuitable for landfill.

They carry with them potential environmental liability when improperly managed or disposed.

Waste solids can’t be left at site untreated, and transporting them for disposal can be expensive and complicated.
Contaminated Water Production in Old Oil Fields With Downhole Water separation: Effects of Capillary Pressures and Relative Permeability Hysteresis
Authors: Inikori Solomon O. , Wojtanowicz Andrew K.
Published: December 2007

Industry operators using downhole water separation technology in bottom water drive reservoirs with water coning problem have employed two major approaches. One approach uses downhole hydrocyclone and pumps to separate water from oil in one co-mingled production stream. This approach involves elaborate completion design and high cost equipment. The second approach, termed "gravity segregation" uses dual completion technology with zonal isolation packer to separately produce the water and the oil and so counter the cone development at the wellbore. Both methods, currently, do not completely eliminate the problem of contaminated water production but reduces it to, perhaps, some manageable level. The growing emphasis on environmental-friendly oil production operation and increasing cost of water handling requires the production of oil-free disposable water in a simple completion design.

This paper presents case studies of the pre-installation design of gravity segregation method for three fields (West Africa, Gulf Canada and Louisiana) with strong water coning problems. The study confirms that old oil fields that have suffered severe water coning exhibit a transitional saturation profile and dispersed oil-water contact. In addition, the imbibition/drainage process of water cone development and reversal induced by gravity segregation creates relative permeability hysteresis effect. The effects should be included in the pre-installation modeling.

The results using numerical simulator, indicate that the combined effects of capillary transition pressures and relative permeability hysteresis are responsible for the production of contaminated water experienced with application of the gravity segregation approach in old oil fields. It also shows how to add an envelope to the well's inflow performance window to accommodate the transition zone. Inside the envelope production of oil-free water from the bottom completion is possible with production of minimal water cut oil at the top. This uncontaminated water could be disposed while operators maximize the use of their pipeline and water separation facilities as well as improve oil recovery.
Produced Water Management Strategy with the Aid of Decision Analysis
Authors: Evans Robin
Published: December 2007

Decision analysis is presented as a tool for carrying out a thorough and logical evaluation of alternative strategies to systematically determine the best available produced water management strategy, both economically and environmentally by the application of environmental accounting.

The use of decision analysis is presented as the framework for conducting integrated produced water management studies. The integration of reservoir engineering, environmental regulations, environmental impact assessment, geochemistry, geological studies, process design, risk analysis, QC and financial appraisals with the aim of optimising scale control will be addressed.

The value of decision analysis is not only in helping to structure information and thinking, but also in providing a vehicle for communication between different groups and technical disciplines. A complex decision problem is decomposed into separate components, often in the form of a decision tree, on which perceptions of options, uncertainties and values can be explicitly represented.

The evaluation of options for produced water management will be used as a case study illustrating the stages of the decision analysis process, which are: Structuring and decomposition of the problem including the evaluation of the options for produced water disposal such as re-injection or surface disposal dependent on environmental regulationsAssessing the payoff of the possible outcomesAssessing risks and uncertainties such as injectivity impairment, aquifer pollution, process upsets, regulation changes etcSpreadsheet construction of decision treesSensitivity analysis and assessing the value of additional information to help finalize the decisionStrategy selection
Tenth SPE Comparative Solution Project: A Comparison of Upscaling Techniques
Authors: Christie M A , Blunt M J
Published: December 2007

This paper presents the results of the Tenth SPE Comparative Solution Project on Upscaling. Two problems were chosen. The first problem was a small 2D gas injection problem, chosen so that the fine grid could be computed easily, and both upscaling and pseudoisation methods could be used. The second problem was a waterflood of a large geostatistical model chosen so that it was hard (though not impossible) to compute the true fine grid solution. Nine participants provided results for one or both problems.
Environmental Data Management Systems for E&P Operations
Authors: Liles Robert J.
Published: December 2007

As environmental managers are faced with an ever-growing number of facilities and environmental regulations, many have opted to implement an environmental data management system. These systems are generally computer-based applications that track, calculate, and report emissions, track permit and regulatory requirements, determine applicability of regulations, track compliance activities, and warehouse pertinent documents. Development of a successful system requires significant planning and also requires that a company's business practices be integrated into the final product. This paper discusses the attributes of a successful system and provides a roadmap for their development and implementation.
Development of Consistent Methodology for Estimating Greenhouse Gas Emissions from Oil and Gas Industry Facilities and Operations
Authors: Lev-On Miriam , Ritter Karin , Retzsch Walter
Published: December 2007

Understanding the sources and quantities of greenhouse gas (GHG) emissions are critical to developing an emissions inventory that accurately represents various oil and natural gas industry segment operations. To address this, API formed a Greenhouse Gas Emissions Methodology Working Group. The working group's objectives are to review, summarize, and recommend methodologies for consistent estimation of greenhouse gas emissions from oil & gas industry facilities.

This paper will discuss the process undertaken to review and compare methodologies used by member companies, national governmental bodies, and intergovernmental experts. It will highlight technical, scope, and boundary considerations that play key roles in the final inventory calculations. It will also present a general classification scheme for all oil & gas industry devices and operations, while identifying the parameters needed to generate robust estimates of emissions for each equipment category and oil & gas industry segment.