bluuebunny/crossref_metadata_2025 huggingface dataset:
Success Of Water-Alternating-Steam-Process for Heavy Oil Recovery
Authors: Ramlal V. , Singh K. Sono
Published: December 2007

The recent period of depressed oil prices which reached as low as $US 5.97/bbl for heavy oil drove major reviews in heavy oil recovery economics, and led to a substantial shift in the operation of four (4) of Petrotrin's thermal projects. The shift was predicated upon key factors such as: experience derived from the North Fyzabad project, a mature steamflood which was converted to a heat scavenging project in 1996the need to assure project viability by maintaining a reasonable lifting cost.at least sustain the present level of decline rates associated with each project.

In February 1999, North Palo Seco, Apex Quarry and Bennett Village, three (3) mature thermal projects at Petrotrin were placed on the water-alternating-steam-process (WASP) and another, Central Los Bajos was converted in August 1999. The four (4) projects are in close proximity each exploiting the Lower Morne L'enfer sandstone and their operating and reservoir characteristics are quite similar. In two (2) of the schemes, selected patterns were converted to WASP, the other patterns being kept on continuous steam. The criteria for pattern selection were pattern temperature, steam-oil-ratio, produced WOR, susceptibility to steam breakouts, and minimal alteration to main piping system.

The paper discusses capital expenditure for the conversion which was kept to an absolute minimum, operating cost which was subsequently reduced; profitability which increased; reservoir response to water injection which resulted in an increase in oil production rate and problems associated with implementation. The paper also discusses techniques of day-to-day flood monitoring, highlights operational problems and presents future operating strategies.
World's First Application of "Self-Locating" Technology for Re-Entry of Milled Casing Windows
Authors: Bailey Ernest C. , Steele David J. , Tank Willard J.
Published: December 2007

Traditionally, operators have had limited options for conducting remedial work on lateral re-entries through milled-casing windows. This limitation is due to the necessity of using a "bent joint" of pipe to guide tools through the window. If a bent joint of pipe cannot be attached to the end of the assembly (e.g. a drilling assembly), a whipstock is required to deflect the assembly out the window. Setting a conventional whipstock requires the use of orienting tools that add significantly to the wellcost.

This paper describes the world's first applications of unique technology that helps solve these problems by facilitating the exiting of milled-casing windows with service tool assemblies during remedial operations. The system uses the patent-pending "self-locating" lateral re-entry technology as an integral component of the Lateral Re-entry Whipstock to assure the proper orientation and elevation of the whipstock tool face with the casing exit window.

The technology described in this paper has bearing on TAML Level II 1 junction re-entry operations for clean out, production enhancement, increased reservoir drainage, zonal isolation, and re-completion of lateral wellbores in multilateral completions.
Effect of Finite Conductivity Horizontal Well on Transient-Pressure Behavior
Authors: Baba Abdessatar , Tiab Djebbar
Published: December 2007

This study investigates the effect of horizontal wellbore hydraulics on the early time dynamic behavior of horizontal wells. A finite conductivity model has been developed to couple infinite-conductivity horizontal well model based on uniform flux solution and finite conductivity wellbore hydraulic model.

A sensitivity study is presented to show: The effect of horizontal well conductivity on production distribution along the wellbore at different time-steps, including early time radial flow, intermediate time linear flow and late time radial flow.The effect of wellbore length on the magnitude of wellbore-pressure drop under different values of Horizontal Well Conductivity, CHD, and Reynolds number, NRe.The effect of pipe roughness, Rp.The effect Reynolds number at the downstream end of the well, NRe.

The new finite conductivity model is evaluated by setting a computer programs using Mathlab programming. The programs can include any friction factor correlation and production scheme.

Type curves, of dimensionless pressure and pressure derivative versus dimensionless time, are obtained for different values of horizontal well conductivity and Reynolds number. These sets of curve can be used for type curve matching techniques.

Correlations of the additional pressure drop due to finite conductivity solution over infinite conductivity solution, ΔPD(tD), are presented for different values of dimensionless well length, LD, horizontal well dimensionless conductivity, CHD, Reynolds number, Re, and pipe roughness, Rp.
Literature Review on Correlations of the Non-Darcy Coefficient
Authors: Li Dacun , Engler Thomas W.
Published: December 2007

Darcy's law can not describe fluid flow accurately when the flow rate is high. In most cases in the recovery process, fluid flow is governed by Darcy's law. But when the flow rate is very high, for an instance, near the wellbore, Darcy's law is inadequate to describe fluid flow.

In 1901, Forchheimer put forward a classical equation, known as the Forchheimer equation, to make up the deficiency encountered by Darcy's law at high flow rates. He added a non-Darcy term into the Darcy flow equation. The non-Darcy term is the multiplication of the non-Darcy coefficient, fluid density, and the second power of velocity. One of the most important aspects in determining the non-Darcy effect is to estimate the non-Darcy coefficient as accurately as possible.

In this paper, theoretical and empirical correlations of the non-Darcy coefficient in one-phase and multi-phase cases in the literature are reviewed. Most researchers have agreed that the non-Darcy effect is not due to turbulence but to inertial effect. The non-Darcy coefficient in wells is usually determined by analysis of multi-rate pressure test results, but such data are not available in many cases. So, people have to use correlations obtained from the literature. This paper summarizes many correlations in the literature, and will provide a good reference for those who are interested in the investigation of the non-Darcy effect in the recovery process.
Analysis of Factors Affecting Microscopic Displacement Efficiency in CO2 Floods
Authors: Sehbi Baljit S. , Frailey Scott M. , Lawal Akanni S.
Published: December 2007

The displacement efficiency of a CO2 flood has two components: microscopic and macroscopic displacement efficiency. This work focuses on the factors that affect microscopic displacement efficiency. The factors are pressure, temperature, oil composition, CO2 purity, fluid properties, and reservoir pore configurations. These factors contribute to the phase behavior of a particular CO2 flood. Mixing as a result of diffusion improves microscopic displacement efficiency as compared to mixing by dispersion, which decreases microscopic displacement efficiency. Phase behavior governs the development and sustenance of CO2 miscibility with crude oil at reservoir conditions. Lower injection rates and higher residence time increases mass transfer between the oil and CO2. Improved transfer leads to oil swelling and viscosity and surface tension reduction that improve microscopic displacement efficiency. Uniform pore geometry and favorable pore structure causes higher microscopic displacement efficiency. The presence of dead-end pores decreases the displacement process. The volume and distribution of water within the pore affects the contact area between CO2 and the crude oil and can impede the miscibility process. As possible, this work quantifies the affect some of the factors have on microscopic displacement efficiency and suggests means of improving the displacement process.
Effects of Carbon Dioxide Curtailment on a Technically Successful CO2 Flood
Authors: Frailey Scott M. , Lawal Akanni S.
Published: December 2007

The cessation of CO2 injection may be the result of poor reservoir response, low oil prices, or near the end of a CO2 project. The focus of this paper is to describe the effect of CO2 injection curtailment on oil recovery and production in a technically successful CO2 flood of an oil reservoir. The CO2 curtailment is sustained over a significant period of time while water is injected. Following the curtailment, CO2 is again injected.

Early EOR literature covers CO2 and miscible gas injection in the presence of very high water saturation. The key issues are phase behavior, surface tension, viscosity, and oil stripping, which are described in terms of curtailment and the subsequent affect on oil production.

A survey of pertinent literature has been conducted to infer the impact CO2 curtailment has on reservoir performance. Preliminary findings are that the curtailment of CO2 leads to a permanent loss in reserves and production rate. Scenarios that may alleviate these losses such as reduced CO2 injection instead of complete curtailment are addressed.
Corrosion Consequences of Oxygen Entry Into Sweet Oilfield Fluids
Authors: Martin Richard L.
Published: December 2007

This paper contains the results of laboratory and field tests where the corrosion system was carbon steel exposed to oilfield brines containing dissolved carbon dioxide and oxygen. Both uninhibited and inhibited systems were examined. The results are analyzed and placed in context with previously reported work dealing with related systems.

Oilfields, in general, have less gas pressure as they mature. Ingress of oxygen into well annuli, into the vapor space in tanks, and through pump packing becomes more commonplace as a result. The corrosion consequences of this condition can now be quantified and corrective action can be taken to avoid equipment replacement and production losses.

To the author’s knowledge, no report of a systematic treatment of this subject exists in corrosion literature. Quantification of the effects, recognition of duration, and influence of corrosion inhibitor chemical types are among the novel contributions of this paper.

Some of the significant conclusions from the work concern the magnitude and persistency of corrosion acceleration by oxygen in sweet fluids. At common oil well temperatures, acceleration was in the order of 10 to 30 mpy per part per million of oxygen. The concentration of oxygen was not reduced preferentially from these solutions but occurred at approximately the same rate as reduction of dissolved carbon dioxide (undissociated carbonic acid) concentration. Inhibition of corrosion in CO2/O2 systems was more difficult that in CO2 alone but could be accomplished.
Slickline-Deployed Electro-Mechanical Intervention System: A Cost-Effective Alternative to Traditional Cased-Hole Services
Authors: Foster Jerry , Clemens Jack , Moore Darrell W.
Published: December 2007

During the ‘90s, the introduction of battery powered electro-mechanical intervention tools increased the versatility of slickline service and changed its image from a simple method that performed mechanical workovers to a complex service technology that could provide safe, cost-efficient alternatives for: locating downhole tubular goods/profilesproducing quality logs from downhole memory surveys at half the cost of traditional servicesaccurate depth measurement for support of all new completion technologiessetting packers without explosivesperforating or cutting tubing or casing.

Slickline has again expanded its capabilities. In addition to its proven performance for well remediation, maintenance, and pressure control applications, the new enhancements to the self-powered slickline tools can now be used to perform diagnostic and conformance control functions requiring memory production logging.

Applications that require electrical initiation or mechanical manipulation at the tool interface can now be performed with slickline and battery power, insulating the tools from the surface equipment. Mechanical signals transmitted through the wire control the tool start and stop functions and provide real time position telemetry. As a result of the advances in service tools, slickline has increased the scope of its services without a compromise to operational safety and job efficiency and offers the most cost efficient services in well workovers.

The case histories will describe how the electro-mechanical intervention tools provide a cost-effective alternative to traditional cased-hole logging systems for many applications as well as many operations that traditionally had to be performed by other service options.
Waterflooding: Review of West Texas Experience
Authors: Adisoemarta Paulus S. , Frailey Scott M. , Lawal Akanni S.
Published: December 2007

A tremendous effort has been made by the oil industry and others over the past seventy years to develop an understanding of multiphase fluid flow through porous media. A vast literature of concepts, field and laboratory data, experimental techniques and mathematical expressions has been developed. Many parameters believed to be pertinent have been investigated, such as connate water saturation, relative permeability saturation relations, sample wettability, and waterflood scaling (including the effect of such variables as pore size, flow rate, viscosities and interfacial tension of the fluids, sample size, and the effect of a third phase such as free gas). Other works investigated are the development of the Buckley-Leverett concept of fluid displacement, the laboratory determination of relative permeability, and the development of waterflood scaling theory aimed directly toward calculating reservoir performance from laboratory data. This paper reviews waterflood management practices in West Texas and provides ways of implementing successful waterflood project.
Saturation Exponent n in Well Log Interpretation: Another Look at the Permissible Range
Authors: Adisoemarta Paulus S. , Anderson George A. , Frailey Scott M. , Asquith George B.
Published: December 2007

Saturation exponent n in Archie’s water saturation equation is the exponent value in water saturation that establishes the relationship between water saturation of the rock to the ratio of fluid filled rock resistivity to the actual rock resistivity. Most theoretical derivations show that there is no exponent or that n is equal to one. However, decades of results from core analyses and openhole log analyses show n greater than one and most often assumed to be two.

Most of the literature is in agreement that the saturation exponent is affected by wettability and saturation history (drainage or imbibition). Furthermore, the saturation exponent depends on rock type, primarily the manner in which the conductive water is connected and configured. Several authors quote values of n ranging from as low as 1 to over 20 for strongly oil wet rocks. Too often an assumed value is accepted as correct.

This paper reevaluates the relationship between water saturation and rock resistivities in order to determine the significance of n and make recommendations on improving an assumed value for n.
Surfactants Oil Displacement System in High Salinity Formations: Research and Application
Authors: Wang Yefei , Wang Lushan , Li Jiyong , Zhao Fulin
Published: December 2007

Aimed for the need of oil displacement in high salinity formations where the normal nonionic and anionic surfactants are inefficient because of salting out or cloud point phenomena[1], A novel structure surfactant(LF) with nonionic and anionic hydrophilic group is put forward and synthesized. The said surfactant is soluble in 30% NaCl brine, and shows good surface activity in brine with 100,000mg/L salinity concluding 5,000mg/L CaCl2. By analysizing the volume fraction-salt concentration phase graph, the salt tolerance property of LF, petroleum sulfonate and their combined system is comparatively studied , LF is excellent, the proportional increment of LF in combined system will improves salt tolerance property of the combined system. In any different brine , water/n-decane Interfacial tension is high if only LF or petroleum sulfonate is used, but Interfacial tension will reach super low if the combined system is appropriately used as long as water salinity is enough high(higher than 20,000mg/L). By adjusting the proportion of LF and petroleum sulfonate in combined system, water/oil Interfacial tension can always reach super low regardless of water salinity, so the system can be particularly used as oil displacement agent in high salinity formations. The paper presents three oil displacement and one chemical tuff and puff formulations consisted of LF and KPS, which were suitable for high salinity formations in Zhongyuan oil field.

The temperatures of four test zone are 86.9°C, 65.0°C, 82.5°C and 82.5°C, the salinities are 88,540 mg/L, 55,028 mg/L, 14,9127mg/L and 195,000 mg/L, the room recovery improvement all exceed 19%.

Now the four field tests get along favorably, verifying good result and indicating bright application prospect.
Residual Processing in FCC
Authors: Guzmán J. D. , Ruiz M. D.
Published: December 2007

When the company decided to participate in the international market, it became necessary to increase the throughput in the Refinery. At that moment, fuel oil had a very low price, so there was no incentive to increase the feed to the Topping units once the capacity of the vacuum and coker units was surpassed.

After a strategic analysis an opportunity was founded in the operations of the two cat crackers. The idea of feeding these units with atmospheric bottoms and converting them into valuable products, showed a very good economic return. This was based in the fact that both crackers were operating in a low utilization mode.
Foamed Cement Selection for Horizontal Liners Proves Effective for Zonal Isolation—Case History
Authors: Harlan Tony D. , Foreman Jay M. , Reed Shawn D. , Griffith James E.
Published: December 2007

This paper describes the reasons for and execution of four foamed cement jobs to provide zonal isolation for a 4 ½-in. horizontal liner. Foamed cement was selected as the most effective means to help achieve all of the following objectives:

High mud displacement in a small annulus Hole cleaning on the low side of the hole No free water or gas channel development Low slurry fluid loss Containment of stimulation treatment in selected porosity streaks Prevention of cement sheath cracking

The benefits of foamed cement vs. non-nitrified cement as they relate to the above objectives are explained in the body of the paper. From the analysis, foamed cement can be a far superior and effective means of providing long-term zonal isolation when compared to conventional, non-nitrified cements.

The paper also outlines steps taken to execute the foamed cementing operation on horizontal liners of four Wyoming wells. Included are best practices for pre-job analysis and planning, job execution, and post-job evaluation.
Case Studies on New Methods of Technology Transfer and Development
Authors: Kiker Robert D.
Published: December 2007

The PTTC poster session"s theme is to illustrate a new method of technology transfer that was developed as a joint venture between the PTTC and World Oil magazine. The Petroleum Digest, a supplement to World Oil, was the vehicle developed for technology transfer of case studies to independent operators. Independents, in particular, rely on field-oriented case studies when they consider applying new technologies. PTTC supplies the case study technology results and World Oil publishes the case studies.
3D-Reservoir Characterization and Reservoir Management Study
Authors: Gaber Nabil Salah , Hughes Samuel C. , Afify Hassan A.A. , Stoner Douglas T. , Artigas Gabriel T. , Mercado Gary M.
Published: December 2007

An extensive, multi-discipline field study was completed in 1999 on the October J Nubia reservoir, located in the Gulf of Suez, Egypt. Although this field is relatively small (7 active wells, 132 MMBO OOIP) as compared to other Gupco's fields, the study proved worthwhile, generating three development prospects, all of them have been drilled and resulted in a rate increase of 6000 BOPD and a reserve gross of 6.6 MMBO.

The study team built a comprehensive, 3-dimensional Earthvision reservoir property model which was an excellent building block for understanding reservoir volumes and performance. The property model provided the tools necessary to understand fluid migration across faults in a 3dimensional setting. The structural analysis began with the reinterpretation of a full-field, 3-dimensional seismic data set. The structural model was then populated with petrophysical parameters to produce the property model.

Extensive reservoir performance mapping also helped our understanding of fluid movement within the reservoir and helped identify areas of bypassed pay. As an example, watercut maps constructed for each of the fourteen reservoir subzones helped determine primary pathways of water encroachment.

The reservoir is a tilted fault block encompassing 750 acres. The producing formation is the highly prolific carboniferous Nubia sandstone with an average gross pay thickness of 600 feet, net pay thickness of 375 feet, porosity of 23 percent, and permeability in the darcy range. The reservoir has a fairly strong natural waterdrive, helping maintain reservoir pressure above the bubble point.

Even though the reservoir was forecasted to recover 48% of the original oil-in-place, the study located three areas of poor sweep. The three authorized drilling prospects are estimated to recover an additional, risk-weighted reserves of 9 MMBO. In addition, a detailed zonal performance analysis helped identify perforation and conformance work in existing wells, which should recover an additional 3 MMBO. The resulting property model and reservoir development plan now provide the operational tools necessary for managing this property for the next several years.
An Integrated Work-Flow Model to Characterize Unconventional Gas Resources: Part II—Formation Evaluation and Reservoir Modeling
Authors: Rushing J. A. , Newsham K. E.
Published: December 2007

This paper presents a systematic methodology to describe and characterize unconventional natural gas reservoirs. We have modified the Petrophysical Integration Process Model (PIPM), originally developed at Amoco (Gunter, et al,1,2), for specific applications to unconventional gas systems. Our modified PIPM, which is divided into four discrete analysis stages, integrates data from multiple sources and different reservoir scales. In this paper, we describe each PIPM stage and show how petrophysics can be used as the critical link between geology and reservoir engineering. Although we illustrate the process with examples from a tight gas sand study, the modified PIPM is applicable to other unconventional gas systems. The ultimate goal of this process modeling is to build realistic three-dimensional wellbore and reservoir flow models to predict future performance and optimize field development.
Hole Shape from Ultrasonic Calipers and Density While Drilling – A Tool for Drillers
Authors: Maeso Carlos , Tribe Ian
Published: December 2007

A number of calipers and hole size indicators (be they by direct measurement or derived) have been introduced with the logging while drilling (LWD) suite of measurements. These include ultrasonic calipers, derived density calipers, and electrical calipers from resistivity tools. Qualitative indications of borehole shape can also be derived from Pe and density measurements which can be affected by tool standoff. The traditional uses of borehole shape measurements have been principally aimed at petrophysicists, reservoir engineers, and geologists for completion strategy, hole volume determination, correction of electrical logs, borehole stability, and borehole size for images. In this paper we summarize additional applications for drillers: To assess the borehole quality related to the drilling process and borehole assembly being used.To diagnose wellbore stability problems while drillingTo identify hole quality which may affect running the completion or wireline tools

Hole shape analysis is carried out by processing azimuthal ultrasonic caliper, Pe, and density data into 1D, 2D, or 3D images to illustrate the borehole shape. Processing of images or caliper curve data in real time enables decisions to be made about modification of the BHA or reconsider drilling practice for the remainder of the well.

An obvious application of the images is to visualise the severity and nature of any borehole breakout occurring and to take necessary steps to resolve the problem, for example by increasing mud weight.

Our results of processing a number of wells highlight that in many cases the shape of the borehole can be directly related to the drilling process. Examples are shown of boreholes drilled by rotary steerable assemblies and mud motors (with different stabilizer configurations and different drilling modes). Timely feedback of this information to the driller allows changes in the style of drilling or BHA to improve the borehole shape and therefore drilling efficiency. This in turn should lead to an improved shaped borehole and better petrophysical data. Understanding the effects of the drilling process can also allow differentiation of drilling induced shape artefacts and geological reasons for borehole shape changes (e.g. zones of instability or breakout).

Information on the shape of the borehole also improves the decisions made for completion strategies where mechanical calipers are not being run. Applications include understanding borehole shape for expandable screens and cement volumes.
Another Look at Layered Prospects
Authors: Murtha J. A. , Peterson S. K.
Published: December 2007

Often a drilling prospect has multiple horizons, each with its chance of success and its volumetric estimate of reserves. A proper evaluation of these prospects acknowledges the multiplicity of possible outcomes, ranging from total failure to total success. If the layers are independent, it is simple to assign probabilities to these outcomes. Whether one seeks a simple mean value or a more sophisticated Monte Carlo simulation, the independence assumption gives a straightforward procedure for estimating aggregate reserves.

When the layers are dependent, however, the aggregation problem becomes more subtle: the success or failure of one layer alters the chance of success of other layers, and the corresponding probabilities of the various combinations of successes are more difficult to calculate. Moreover, the rules of conditional probability, notably consequences of Bayes’ Theorem, provide challenges to those who assign estimates for the revised values. Even in the case of two layers, some estimators incorrectly assign these values by failing to quantify correctly their interdependence. These issues were addressed by Murtha1, in which a method was proposed to overcome the pitfalls of conditional probability. Then, at the SPE 2000 ATCE, Delfiner2 and Stabell3 offered alternative procedures for handling dependence.

We propose a new Monte Carlo simulation method, which is simple to describe for two layers, is based on tested concepts, can be shown to yield desired conditional probabilities, readily extends to any number of layers, and, most importantly, always honors Bayes’ Theorem.

As in the earlier paper1, the generic form of this model can be applied to prospects in adjoining fault blocks, step-outs, and other forms of multiple targets that should be regarded as a package when ranking prospects.
A Portfolio Management Approach to Assessing Acquisition and Divestiture Candidates
Authors: Allan Paul D.
Published: December 2007

The trend towards consolidation in the E&P sector has resulted in significant opportunities for smaller companies to acquire the non-strategic assets of larger companies as portfolios are rebalanced and assets are rationalized. Properties or prospects viewed as non-core or materially insignificant to the majors may have the potential to significantly impact the portfolio of an independent. This paper outlines a specific approach to evaluating acquisitions and divestitures in terms of portfolio value and risk management. Case studies are used to demonstrate how portfolio management can assist a company in appropriately evaluating an asset by quantifying the impact an asset has on the company's ability to meet its targets. The concept of portfolio value as opposed to deal value is described in an effort to demonstrate the interactions between project selection and targets within a portfolio. The examples will demonstrate the benefits of a portfolio management approach, particularly when dealing with the complexity of multiple projects, timing variability, market risks, and variability in asset performance.
Direct Experiments on the Ocean Disposal of Fossil Fuel CO2
Authors: Brewer Peter G. , Peltzer Edward T. , Orr Franklin M.
Published: December 2007

Substantial progress has been made in carrying out small-scale field experiments to investigate the scientific basis for disposal of CO2 that results from burning of fossil fuels in the deep ocean. A remotely operated vehicle (ROV) was used to carry liter quantities of CO2 to depths from 250 to 3650 m in the ocean and to release the CO2 in a controlled manner. A video imaging system allowed observation of the behavior of the CO2 released. CO2 released at intermediate depths forms bubbles that rise. Below about 2750 m liquid CO2 is more dense than sea water, and CO2 released at greater depths descends further. Hydrate formation was observed for depths below about 350 m. We show through video imagery, direct measurement, and model calculations that the dissolution rate of liquid CO2 in the deep ocean is 3 pmoles/cm2/sec. The slow dissolution rate limits the local concentration of CO2. Limited observations of the approach of marine life to CO2 released on the sea floor showed no apparent avoidance reactions.
Multiphase Flowmeters in Well Testing Applications
Authors: Theuveny B. C. , Ségéral G. , Pinguet B.
Published: December 2007

Dual-energy spectral gamma ray / Venturi multiphase flowmeters present an efficient and cost-effective means of testing wells in many field applications. A simple, efficient and quick procedure optimizes the utilization of these types of multiphase flow meters for well testing. This paper presents the field operating procedures for installing and using multiphase flowmeter and gives practical recommendations for performing well tests with or without a reference, such as a separator. The analysis of 415 multiphase well tests performed worldwide has provided some insights into the accuracy achieved in the field and has led to some recommendations for the test design.

The ability of a multiphase flowmeter to perform a measurement in the absence of a flowing reference is essential to well testing in most applications. Furthermore, the high mobility of the equipment (with up to three wells tested in three different locations per day) allows a very efficient and short turn around time for installation and operation.

The parameters required to perform the setup of a meter fall into two categories: meter static empty pipe reference and fluid properties. A detailed review of each parameter is presented along with its sensitivities when determining the flow rates of oil, gas and water. A description of the field procedure used to determine each setup parameter is provided and a series of field examples are presented that illustrate the efficiency of using multiphase flowmeters for well testing.
Segregated Flow is the Governing Mechanism of Disproportionate Permeability Reduction in Water and Gas Shutoff
Authors: Stavland A. , Nilsson S.
Published: December 2007

This paper describes the mechanism for disproportionate permeability reduction (DPR). Recent papers have discussed possible DPR mechanisms. Most of the papers conclude that there is not yet a single factor that determines DPR. The intention of this paper is to clarify that there is a single model, which explains the observed DPR effects. This model relies on segregated flow of oil and water at pore level and on continuity in the oil phase at placement of the DPR fluid. With this model DPR is demonstrated for both gel and single polymer systems at different wettabilities. Oil continuity is normally easier to obtain for single polymers than for crosslinked gels. Gel systems may, however, be more robust. The paper describes a method for placement of water-soluble gel while maintaining open pathways for oil. Additionally, it is shown that using the phase permeability reduction ratio is not a good measure for defining optimum DPR. Therefore a new selectivity parameter is introduced which demonstrates to be more effective.
Production Analysis of Long-Term Linear Flow in Tight Gas Reservoirs: Case Histories
Authors: Arevalo-Villagran Jorge A. , Wattenbarger Robert. A. , Samaniego-Verduzco Fernando , Pham Tai T.
Published: December 2007

Actual field data show linear flow in a large number of tight gas wells. Sometimes this linear flow is transient for years. Linear flow is normally associated with hydraulic fractures. Short-term linear flow production analysis may characterize fracture treatments, but long-term linear flow production may be controlled in some cases by the reservoir geometry; in others, it is controlled by the natural occurring reservoir properties. In this paper, long-term linear flow caused by both the presence of natural parallel fractures and vertical flow in a high permeability streak is investigated. An analytical matrix-parallel fracture model for a single-phase flow is presented. A systematic procedure to analyze linear flow in tight gas wells is described. Application of this methodology to production analysis from several tight gas wells and validation of the results by using numerical simulation are also shown.
Field-Wide Variations of Trapped Gas saturation in Heterogeneous Sandstone Reservoirs
Authors: Hamon G. , Suzanne K. , Billiotte J. , Trocme V.
Published: December 2007

Maximum residual gas saturation (SgrM) is known to be a key factor to evaluate the gas recovery from a lean gas reservoir invaded by aquifer water. This work focuses on variations of SgrM within heterogeneous gas-bearing sandstone reservoirs. Our aim is to produce a reservoir model based on SgrM values consistent with petrophysical trends. Literature presents no SgrM values below 20 % and reported trends usually indicate that SgrM decreases as porosity increases.

Three hundred measurements of SgrM have been performed by liquid capillary imbibition at laboratory conditions on dry plugs. The following data are also available: lithological description, thin sections, XRD analysis, NMR measurements, porosity, permeability, grain density, formation factor and cementation factor. The core plugs are selected from two Far East and one West Africa sandstone gas reservoirs and from Fontainebleau Sandstone outcrops. Plug porosities and permeabilities, respectively range from 6 % to 25 % and from 0.1 to 3 000 mD, with clay content ranging from 0 to 33 %. The main results are:

SgrM values are very scattered from 5 % to 85 %. SgrM against porosity plots present three major trends: – Two very different but clear trends exist in the low to medium porosity range (below 14 %). As porosity decreases, SgrM increases for Fontainebleau sandstone whereas it decreases for other sandstones. – Concerning the highest porosity values, i.e. above 14 %, the two above mentioned trends merge to an average of around 25-35 %. No relationship exists between SgrM and either grain density, or formation factor, or cementation factor. The amount of clay controls the SgrM versus porosity relationship. SgrM decreases as the clay content increases. No relationship was found between the type of clay and SgrM. SgrM decreases as microporosity, as represented by the NMR Clay-Bound Water, increases. It suggests that microporosity does not trap gas.
The Optic Oil Field: Deployment and Application of Permanent In-well Fiber Optic Sensing Systems for Production and Reservoir Monitoring
Authors: Kragas Tor K. , Williams Brock A. , Myers Gregory A.
Published: December 2007

Development and exploitation of oil and gas resources in increasingly difficult operating environments such as deepwater raise many technical challenges. Among these is the ability to provide assurance on the completions and production from high-cost and complex wells. Real-time, permanent wellbore and reservoir monitoring is a critical technology for providing assurance and maximizing profitability of these fields.

Recent developments in fiber optic sensing technology have resulted in reliable alternatives to conventional electronic systems for permanent, downhole production and reservoir monitoring. In-well fiber optic sensors are now being developed and deployed in the field for measuring temperature, pressure, flow rate, fluid phase fraction, and seismic response. Bragg grating-based fiber optic systems combine a high level of reliability, accuracy, resolution and stability with the ability to multiplex sensors on a single fiber, enabling complex and multilateral wells to be fully instrumented with a single wellhead penetration. These systems are being installed worldwide in a variety of operating environments for a variety of applications.

This paper presents several recent deployments of in-well fiber optic monitoring systems, including descriptions of the downhole sensor assemblies, installations, and measured data. Installations of fiber optic pressure and temperature systems in a land well and in the Gulf of Mexico and an all-fiber flow and liquid fraction system in deepwater Gulf of Mexico are discussed. A general description of fiber optic sensing and Bragg grating-based sensing systems is also presented.
Active Feedback Control as the Solution to Severe Slugging
Authors: Havre Kjetil , Dalsmo Morten
Published: December 2007

Severe slugging in multiphase pipelines can cause serious and troublesome operational problems for downstream receiving production facilities. Recent results demonstrating the feasibility and the potential of applying dynamic feedback control to unstable multiphase flow like severe slugging and casing heading have been published (Refs. 4,9,1,5 and 2). This paper summarizes our findings on terrain-induced slug flow (Ref. 2). Results from field tests and as well as results from dynamic multiphase flow simulations are presented. The simulations were performed with the pipeline code OLGA2000.

The controllers applied to all of these cases aim to stabilize the flow conditions by applying feedback control rather than coping with the slug flow in the downstream processing unit. The results from simulations with feedback control show in all cases stable process conditions both at the pipeline inlet and outlet, whereas without control severe slug flow is experienced. Pipeline profile plots of liquid volume fraction through a typical slug flow cycle are compared against corresponding plots with feedback control applied. The comparison is used to justify internal stability of the pipeline. Feedback control enables in many cases a reduced pipeline inlet pressure, which again means increased production rate.

The paper summarizes the experience gained with active feedback control applied to severe slugging. Focus will be on extracting similarities and differences between the cases. The main contribution is to demonstrate that dynamic feedback control can be a solution to the severe slugging problem.
Crude Oil-Natural Gas Two-Phase Flow Pattern Transition Boundaries at High Pressure Conditions
Authors: Manabe R. , Zhang H.-Q. , Delle-Case E. , Brill J. P.
Published: December 2007

The effects of pressure on flow pattern transition boundaries for crude oil-natural gas two-phase flow were investigated.

Experimental observations of flow patterns were carried out for different pressures (200 and 450 psia) and inclination angles (horizontal, +1 degree and vertical). Special attention was given to the stratified-intermittent transition and the intermittent-annular transition for horizontal and inclined flow, and the transition to annular flow for vertical flow, since these boundaries were known to be sensitive to pressure.

The experimental results show that pressure affects the stratified-intermittent transition for horizontal flow and slightly affects the intermittent-annular transition for inclined flow and for vertical flow. The predictions of transition boundaries by existing mechanistic flow pattern prediction models show good agreement for all transition boundaries described above.
Use of Compositional Modelling in the Development Planning of Gbaran Field, Nigeria
Authors: Matemilola S. A. , Osaigbovo B. O. , Lin C. J.
Published: December 2007

Compositional simulation was applied in the development planning of Gbaran field in Nigeria. A major challenge of the study was to determine the optimal development and management strategy for maximising recovery of both oil and condensate, simultaneously. A full-field simulation model was constructed to accurately simulate the reservoir fluid phase behaviour, study the reservoir displacement and recovery mechanism and optimise the configuration and design of surface facilities. The reservoir fluid was adequately characterised using an 8-component Peng-Robinson equation-of-state model. The model was used to predict future reservoir performance under various developments and operating scenarios and to determine the optimum oil and condensate recoveries. The study showed that an integrated oil and condensate development strategy involving gas re-injection and partial cycling would lead to optimal oil and condensate recoveries of 63 % and 68 % respectively. Under natural depletion however, the recovery for oil would be 49 %, while condensate recovery would be relatively insignificant.
Moderate Velocity Flow in Fractures
Authors: Kløv T. , Skjetne E. , Gudmundsson J. S.
Published: December 2007

Moderate velocity pressure loss in rough fractures in Bentheimer sandstone was analyzed with theory for weak inertia flow in porous media. The pressure loss did not follow Darcy's law nor the Forchheimer equation. Instead the pressure loss is the sum of a linear term and a cubic term in velocity in accordance with a theory for weak inertia flow in porous media and fractures. The Darcy permeability in the linear term is given by a power law in fracture width with a power greater than two. Darcy permeability was modeled by tortuosity for a self-affine fracture and an effective fracture width normal to the flow path. The cubic weak inertia pressure loss is also a power law in fracture width, even though the geometry dependent factor is dimensionless. To the best of our knowledge this is the first experimental result showing that the weak inertia equation describes moderate velocity flow in natural fractures.
Integrating Permeabilities from NMR, Formation Tester, Well Test and Core Data
Authors: Haddad S. , Cribbs M. , Sagar R. , Tang Y. , Viro E. , Castelijins K.
Published: December 2007

Permeability is a critical reservoir parameter that defines well and reservoir performance. An accurate knowledge of permeability is critical to forecasting rates and designing production facilities. The permeability determined from different sources can vary significantly, resulting in inconsistent estimates of well and/or reservoir performance.

In this paper, permeability values and evaluation methods, are discussed and verified with field data. It is shown how NMR derived permeabilities calibrated to MDT or comprehensive core data can be used to define well/reservoir performance. By accounting for the effects of overburden, as well as, pore pressure when measuring permeability in core tests, more representative values of permeability can be determined. These values of permeability can be used to accurately calibrate NMR permeability data.

The simulation and calibration results are compared to measured well test data. Results from this work show that if these various sources are integrated properly an accurate well productivity model can be achieved.
Case Study: Maximizing Productivity with Extreme Underbalance Perforation
Authors: Potapieff Igor , Lallemant Francois , Rusly Albert , Zen Djati Wangsa , Retnanto Albertus , Kermoud Mohamed , Danardatu Heru , Murdiyono Murdiyono
Published: December 2007

Tunu field is the major gas supplier of the East Kalimantan system. It started producing in 1990 and more than 200 wells have been drilled to date. The field exported an average 1.3 bcf/d in 2000.

In early 1999, extreme underbalance perforation (EUB) was introduced for monobore wells to reduce the skin effect to provide more flow capacity and maximize hydrocarbon recovery from the reservoir. The differential pressure between the wellbore and the formation creates a sufficient drawdown to instantaneously clean the perforated channels as soon as they are made. The challenge is to safely perforate under a drawdown of few 1000's psi instead of few 100's psi for classical perforations.

The anchor + stackable perforating gun system has been evaluated and improved to permit EUB perforating to be performed safely. The heart of the EUB gun system is a mechanical release anchor that secures the guns firmly during perforation avoiding the risk of lifting the tool inside the wellbore. As there is no wireline cable while perforating, the well is flowing instantaneously allowing immediate clean up. Using this system, the underbalance is now limited only by: the drawdown on the formation (limited in case of depleted sand) and the potential risk to destabilize the formation and produce sand formation.

So far, 20 jobs have been done safely on Tunu field with the differential pressure up to 4800 psi, without sand production. The paper will describe the operation procedures and the statistical approach (PBU results) demonstrating the benefit of EUB technique.

For Tunu field, this perforation technique increases in average by 15% the initial productivity compared to classical perforations for a relatively low incremental cost.
An Automatic Production Monitoring System - Design and Applications
Authors: Chen Shing-Ming
Published: December 2007

Periodic field measurements and surveys often result in an abundance of data that needs to be analyzed to assist in optimizing the field production. Without a proper approach to managing and interpreting the data, valuable information that may be realized from the data can easily be overlooked.

This paper presents the design and application of an automatic production monitoring system that can be set up on a spreadsheet utilizing the spreadsheet's data operation and graphical capabilities. The program can be used as the ‘first pass’ screening tool to evaluate the production performance. Based on the historical production data incorporating the user-specified criteria, the current performance of each well is categorized as ‘normal', ‘damaged’ or ‘under-performed'. The potential production increases that may be realized by working over candidates in a typical oil field can also be estimated. With the innovative multi-scale plotting and field-wide mapping techniques, the program can provide the reservoir or production engineers with a gross scoping tool for a high-level overview of both individual well behavior and field-scale performance.

In this paper, the design considerations of the program, the advantages and disadvantages of its features, and field examples illustrating its applications are discussed.