bluuebunny/crossref_metadata_2025 huggingface dataset:
Technical & Economic Application Guidelines for Downhole Oil-Water Separation Technology
Authors: Blanco A. E. , Davies D. R.
Published: December 2007

Downhole Oil-Water Separation (DOWS) is a water management technology consisting of a hydrocyclone to separate oil from water together with some form of artificial lift to produce an oil enriched stream to surface and to inject the bulk of the produced water into a disposal zone. Field trials have proven DOWS's operational success at reducing the well's water production, but economic success has been sparser. Increased confidence in DOWS technology depends on the development of improved models and methodologies which: Realistically simulate the complete downhole separation process andEvaluate the operational and economical aspects of DOWS

This paper summarises: The development of a hydrocyclone performance model,Its integration with a reservoir simulator andThe testing of this integrated model against a real field case leading to a reservoir development strategy for evaluating the optimum time for DOWS installation and DOWS economics.

Our single or dual stage, hydrocyclone performance model allows the oil / water separation efficiency to be calculated for a range of operational conditions. A decision tree identifies the optimum DOWS installation time based on both the economical and the operational aspects of the technology. The impact of operational parameters on DOWS viability are assessed, ranked and compared. These include the importance of casing size, electrical power costs, properties of the water disposal zone, potential use of the reject water and the surface water treating costs. As expected, DOWS mechanical reliability is one of the key parameters controlling economic viability.

Use of our DOWS technical and economic models described here, together with the reported application strategy, will allow confident installation of DOWS technology in the field. DOWS may then be counted as a reliable option in the water management armoury and a tool for improved oil recovery.
Diagnosis of Sustained Casing Pressure from Bleed-Off/Buildup Testing Patterns
Authors: Xu R. , Wojtanowicz A. K.
Published: December 2007

When the casing pressure can not be permanently bled off through needle valves at wellhead, the casing is said to exhibit Sustained Casing Pressure (SCP). Since high values of SCP may threaten worker safety and environmental protection, MMS regulations require remedial treatment. Testing of SCP could provide information on parameters causing gas migration and SCP.

A mathematical model for testing SCP buildup has been developed. The objective of the model to identify the flow mechanism of external leak leading to SCP. The model also determines critical parameters of the leak to be used in selecting some remedial actions. Also presented in the paper are two examples of using this model to analyze actual SCP field tests. The analysis gives acceptable estimates of the depth of gas invasion zone, formation pressure, cement conductivity, and expected maximum value of casing pressure.
Improving the Success of Morrow Stimulations the Old-Fashioned Way
Authors: Logan W. D. , Gordon J. E. , Mathis R. , Castillo J. , McNally A. C.
Published: December 2007

The Morrow gas sand reservoirs in southeast New Mexico have permeability values that can range across three orders of magnitude. The best wells are completed naturally; the poorer quality rock usually needs to be fracture stimulated to produce commercially. Early attempts to fracture stimulate the Morrow with water-base systems were only marginally successful. Previous studies have suggested that the poor fracturing response to water-base systems was due to a combination of water-sensitive clays and capillary pressure effects. Early theories were that the Morrow experienced reduced permeability as a result of clay swelling and high water saturations in the zones invaded by fracture fluid filtrate. These issues were addressed by using energized fracture treatments that included high quantities of CO2 and methanol in the fracture fluid. Stimulation success with foams has not been consistent. Successful fracturing response to smaller hydraulic fracture jobs using foams has been observed in higher permeability wells where near-wellbore damage has been successfully bypassed. However, in lower permeability wells where fracture length is critical to stimulation success, foams have not provided economic stimulation results.

Although foams were used to address water-sensitivity issues, undesirable side effects countered the foam benefits. Low viscosities, high friction pressures and high chemical cost resulted in increased screenout frequency and increased treatment cost. Early screenouts with low proppant concentrations have left many Morrow reservoirs producing at rates well below their potential. To achieve optimum inflow potential, a fluid system is required that is capable of developing adequate hydraulic width and transporting larger volumes and concentrations of proppant.

Water-base fracturing fluid technology has come a long way since the early days of Morrow fracture stimulation. Advances in both fluid selection and fracture design now make it possible to use a water-base system to achieve successful stimulation results in the Morrow in southeast New Mexico. The net result of this engineering approach is improved stimulation results with lower treatment cost.

Two examples of successful applications of modern fracturing techniques demonstrate that operators in the Morrow of southeast New Mexico have a choice of fracturing fluids other than CO2 foams.
Morrow Production Enhanced by New, Foamed, Oil-Based Gel Fracturing Fluid Technology
Authors: Vezza Matt , Martin Mike , Thompson Joseph E. , DeVine Carolyn
Published: December 2007

Oil-based fluids were first used in the late 1940's to fracture stimulate a variety of wells, the first of which was in Hugoton Field. Subsequently, fluids evolved with soap and aluminum phosphate esters being employed as gellants. Because gelling, gel stability, and ease of mixing have been historically problematic, a new phosphate ester system has been developed for use in formations which may be damaged by water contact.

The Morrow Formation in the Mid-Continent region is known for its sensitivity to fresh water. Due to this fact, treatment designs have been implemented to reduce the amount of water placed into the formation. Foams and gelled oil treatments have been the options available. Foams, while reducing the amount of water placed in the formation, still have a water phase to deal with. Gelled oils eliminate the water phase, but do not have the benefit of the load recovery assistance provided by the gaseous phase of the foam. This paper details the treatment of the Morrow Formation in Southern Oklahoma in which carbon dioxide is introduced into the gelled oil phase. This practice, while common in Canada, has not been utilized in the United States to a great extent. This paper deals with the development and laboratory testing of the fluid system, the treatment design, and the results of such treatments in Grady County in Oklahoma.
Modeling Well Performance Under Nonequilibrium Deposition Conditions
Authors: Civan Faruk
Published: December 2007

A nonequilibrium well productivity decline model is developed and solved analytically under the same simplifying conditions of the previous equilibrium models. The solution is compared with the analytical solutions of the equilibrium models. It is demonstrated that deposition for nonequilibrium flow conditions is less compared to equilibrium flow conditions. Charts are developed and presented for the productivity index and skin factor in terms of relevant dimensionless parameters. In addition, the formulae for estimation of the radius of the plugging region (skin radius), and the producing time required for partial plugging of the formation at various percentages of the initial porosity and the time for complete plugging of the formation are derived. Numerical examples are presented, illustrating the applications of the formulations, and the predictability of the productivity decline of wells. The new improved model alleviates the limitations of the previous equilibrium models and more accurately predicts the productivity decline. This model can be used for determination of the rate of productivity decline by scale formation, the skin radius, and hence the well inflow performance and for scheduling of the treatments necessary for effective well stimulation.
Total Downstroke Friction From Downhole Dynamometer Analysis
Authors: Long Scott W. , Smith Elton J. , Mehaffey Kirk , Garza Albert S.
Published: December 2007

The oil and gas industry is benefitting from development and use of improved predictive computer programs that now utilize several friction defaults.

These predictive programs are more capable of predicting surface and downhole rod pumping conditions. The need for improved predictive accuracy is requiring program users to adopt improved estimates of downstroke friction to model downhole pumping conditions. Lack of improved estimates of downstroke friction has resulted in program users accepting and designing with current friction defaults. Use of these defaults may culminate with results not representative of actual downhole pumping conditions.

This paper develops a method of estimating total downstroke friction from existing dynamometer analysis. Use of this method in producing fields with similar operating conditions will provide improved estimates of total downstroke friction.

A better understanding of the magnitude of total downstroke friction will result in improved friction defaults. Improved friction defaults will result in more effective designs of rodstrings and artificial lift systems.
The Impact of Non-Darcy Flow on Production from Hydraulically Fractured Gas Wells
Authors: Handren Patrick , Pearson C. Mark , Kullman John , Coleman Robert J. , Foreman Jay , Froebel Keith , Caron Jon
Published: December 2007

The pressure drop due to flow within a propped fracture results from three mechanisms: viscous drag of the fluid, inertial effects associated with the movement of fluid around the proppant grains, and multiphase effects associated with the interaction of the different fluid phases.

Most existing fracture models and production simulators analyze the effects of viscous drag only, often underestimating the total pressure drop in the fracture by one or two orders of magnitude. These models rely solely on the reference permeability of the proppant, which is measured in the laboratory with extremely low flow rates of 2 to 10 cc/min. This paper reviews the design changes necessary to accommodate the incremental pressure losses resulting from multiphase and non-Darcy flow, and shows application of the theory to two operators' stimulation programs.

Production rate projections and economic analyses are provided for fracture treatments conducted in two field programs (both gas reservoirs): Total-Fina-Elf's development in the Frio and Vicksburg reservoirs of South Texas and Chevron USA's Birch Creek Unit in the Green River Basin of Wyoming.

Fracture treatments in existing wells had been designed with traditional Darcy flow models. New stimulation treatments were redesigned to include multiphase and non-Darcy flow effects. This paper provides details of the two different stimulation treatment designs in each of the development programs and the production results – average productivity increases of 20 to 30% for the new wells compared to offset wells treated with stimulations based on Darcy flow design models.
Experimental and Mathematical Modeling of Wax Deposition and Propagation in Pipes Transporting Crude Oil
Authors: Nazar A. R. Solaimany , Dabir B. , Vaziri H. , Islam M. R.
Published: December 2007

One of the problems faced by the petroleum industry is the wax deposition in pipelines during transportation of waxy crude oil. Oil companies dealing with waxy crude often spend millions of dollars in remedial procedures. An ideal design should use an accurate mathematical model that would include all salient features of wax deposition and waxy crude transport to predict wax deposition during crude oil transportation. In this paper, a comprehensive mathematical model both in laminar and turbulent flow regimes is developed. The model couples energy equation with deposition and removal kinetics model and thermodynamic model.

The k-ε turbulent flow model and energy equation were used to predict velocity and temperature distributions in the turbulent flow regime. Molecular diffusion of wax, as a mechanism of deposition and sloughing effect due to the hydrodynamic forces of fluid on deposited wax, have been considered. Parametric studies on the variation of the amount of wax deposition were performed for a mixture of toluene and oil wax cut in an experimental setup. Overall predictive ability of the proposed model is excellent for the laminar flow. For the turbulent flow regime, no necessary complete experimental data for model were available. Consequently, qualitative results were presented and discussed.
Safety Critical Learnings in Underbalanced Well Operations
Authors: Jansen Sjors , Brett Peter , Kohnert Jorg , Catchpole Roger
Published: December 2007

This paper describes Shell U.K. Exploration and Production's (Shell Expro) approach to managing safety critical activities when bringing onshore underbalanced drilling techniques into an offshore North Sea environment.

Prior to 1996 underbalanced drilling (UBD), including low or reduced head had never been carried out, offshore, in the North Sea. However, sound economic justification provided the impetus to introduce this technique and associated technology. There were many significant safety challenges that had to be addressed to demonstrate that the risks were within the limits of tolerability and as low as is reasonably practical (ALARP). The primary HS&E concerns related to: loss of containment (continuous pressure at surface), competence of personnel (UBD differs from conventional drilling operations) and safely designing, installing and operating the new technology required for offshore UBD activities. While UBD had been successfully carried out in many onshore environments it was recognised that this experience did not readily translate to an offshore North Sea environment. Consequently, much of the technique and technology had to be revisited to provide the project team with the necessary level of assurance required to confidently proceed with underbalanced operations. Since 1996, the Shell Expro UBD Project Team has successfully implemented underbalanced drilling; this paper illustrates some of the main HSE issues that need to be managed for UBD operations.
Deepwater Drilling with Lightweight Fluids - Essential Equipment Required
Authors: Hannegan D. M. , Bourgoyne A. T.
Published: December 2007

New equipment described in this paper has been developed for employing underbalanced drilling techniques on a floating drilling rig. Field trials of this equipment are being conducted on a semi-submersible vessel in the Albacora Field of the Campos Basin located offshore Brazil. The test is being conducted in a partially depleted formation with a pore pressure equivalent to approximately 7 lb/gal. The formation will be drilled slightly overbalanced during the test.
Unplanned Disconnects in Deepwater Drilling: Prevention Measures and Emergency Response
Authors: Bruce D. , Foster D. , James R. , Plaisance M. , Kropla S. , Nelson C.
Published: December 2007

In 2000, two unplanned disconnects of the Lower Marine Riser Package (LMRP) occurred on deepwater rigs in the Gulf of Mexico. Both were attributed to human error. The IADC Deepwater Well Control Task Force reconvened to study this problem and investigate preventative measures. The results of this study were presented to the Minerals Management Service (MMS) in July 2000. The report includes recommendations regarding the Primary Control System for prevention of unplanned disconnects as well as guidelines concerning backup systems to maintain or regain wellbore security. The backup systems studied include 1) intervention by Remote Operated Vehicle (ROV); 2) deadman systems/autoshear systems; and 3) acoustic control systems.
Off Setting Kill and Choke Lines Friction Losses, A New Method for Deep Water Well Control
Authors: Botrel Thierry , Isambourg Patrick
Published: December 2007

Deepwater well control with a subsea BOP is often difficult and in many circumstances impossible with the usual methods and procedures. This is not only due to the narrow margin between pore and formation fracture pressures, but also to friction losses in kill and choke lines. Such a situation is aggravated by the sharp rheology increase experienced with synthetic or oil base mud that is caused by the low temperatures deep sea. In some field cases, the gelling effect of mud at low temperature even preclude to start circulating out the kick without exceeding the formation fracture pressure. By injecting base oil or primary emulsion at BOP level, mud hydrostatic, rheology and gelling effect can be significantly lowered. These enable one to compensate for friction losses and to circulate out the kick at a higher flow rate. Kick control through kill and choke lines may be attempted when it is impossible with usual procedures. Computed simulations of this new kick control method applied to some real field cases demonstrate benefits of the method. The decrease of the mud rheology due to the mixture with base oil or primary emulsion is quantified by rheological measurements.
Designing Underbalanced Thru Tubing Drilling Operations
Authors: Nas S. , Laird A.
Published: December 2007

This paper describes the planning issues that will need to be addressed when planning underbalanced thru tubing drilling operations.

Planning a conventional underbalanced well can be complicated at the best of times. Planning a thru tubing underbalanced operation is even more complicated. For a successful thru tubing operation, a significant amount of planning and experience is needed. Very often we see that the service providers for coil or UBD services get asked to help in the planning aspects of a well. Although their experience in executing operations associated with their equipment is significant, planning a thru tubing (TTD) well with the objectives of an operator in mind is not their daily business. We have seen a number of operational failures either as a result of poor planning or as a lack of experience. Many of these failures are being blamed on the equipment or on the technology as many operators are unaware of the current limits of TTD operations. This is partly due to the fact that many thru tubing drilled wells are experimental technology projects with operators testing if thru tubing operations can be executed on their own wells.

It has been proven in Alaska and Oman that a sustained campaign of thru tubing underbalanced drilling can lead to significant cost savings and operational improvements. Yet in many area's of the world, both underbalanced drilling technology and thru tubing drilling technology is not implemented due to uncertainties on the successful outcome of a TTD project. Experience in the planning and operational aspects of a TTD-UBD well is extremely important to achieve a successful outcome.
Continuous Depth-Indexed Analysis of Production-Log Data in Oil-Water Flow
Authors: Hoadley S. F. , Kabir C. S. , Kamal D.
Published: December 2007

Production logs (PL) are traditionally interpreted by collecting depth-indexed information recorded by four major sensors; that is, pressure, temperature, density, and flow velocity. Although foot-by-foot data are gathered during flowing and shut-in passes, flow interpretation is normally done over selected discrete depth intervals, known as stations.

This study explores data analysis on a continuous depth basis rather than that done at discrete stations. In so doing, we obtain unbiased in-situ flowmeter calibration, leading to improved understanding of wellbore flow behavior and production log interpretation.
Global Virtual Teamwork Cracks The Athel
Authors: Bell Matt , Alixant Jean-Louis , Smits Wouter G. , Turner Bob , Maas Jos G. , Ruijtenberg Piet , Hoogeveen Wouter
Published: December 2007

In 1997, Petroleum Development Oman (PDO) assembled a team of experienced engineers to tackle the unique challenges presented by the Athel play. These deep, high pressure, sour oil accumulations found in the South Oman salt basin were known to contain substantial oil in place but were considered sub-economic due to poor productivity resulting from extremely low permeability. The team sought to better understand both the reservoir and its dynamic behaviour, in search of cost-effective development options.

By early 2000 the Athel team had completed three years of focused research and development activities during which time the team evolved into one of the pioneering global teams in the EP sector - the Athel Global Virtual Team (GVT) - calling on a multitude of world-wide resources (both internal and external), managed by an integrated team from PDO and Shell E&P Technology and Research (SepTAR).

Visible progress in 1997 and early 1998 contributed significantly to shareholder confidence in approving a green-field Phase 1 development of the Al Noor reservoir. This has culminated in a fast-track project delivering first oil on 12th August 2000, 30 months after approval. The team has addressed all of the objectives laid down in 1997 and has routinely exceeded project targets.

This paper examines the challenges faced by the team and the evolution of its global virtual structure. Factors contributing to their success are identified and conclusions and key learnings for future project teams are drawn.
Water and Gas Control Jobs in Indian Offshore Field (Bombay High) - Trends and Case Studies
Authors: Sinha G. K. , Sinha R.
Published: December 2007

Bombay high, an offshore oil field was discovered in the year 1974 and was put on production in May1976. Water injection in this field was started in 1984. The main pay zone L-III is of miocene age. L-III is a multilayered, anisotropic limestone reservoir with a gas cap and partial water drive. L-III reservoir of this has 13 different sub layers, which are separated by shale streaks.

Water Shut off jobs: Bombay high wells started producing water since 1984-85. Preferential depletion of high permeability layers in a set of high and low permeability layers perforated together and subsequent preferential flooding of these layers has led to an early break through of water as well as water loading of wells. This has also led to the leaving oil un-drained in less permeable layers. Earlier attempts to shut off water with conventional squeeze jobs met with a little success. However candidate selection with proper diagnostics and mechanical isolation of the squeezed layer has resulted in remarkable success. But this could not address to the middle water producing zones. In order to overcome the limitations of conventional cement squeeze jobs and in search of better success ratio on sustained basis and with the advent of various gel–chemicals, a number of gels of reputed companies were used during 1993-97 for water shut off jobs. However the results were not encouraging either. Recently during 1999-2000, extensive lab studies were done on cores simulated at reservoir conditions and the compatible gels were used. Three water shut off jobs have been done using these gels.

Gas shut off jobs: Success ratio remained low with the cement squeeze in between the oil producing and gas bearing layers. This increased remarkably with improved diagnosis by multidisciplinary team, use of clean work over fluid and mechanical isolation of the squeeze point with packer. Recently during 1999-2000, various gels were tested for compatibility with reservoir rock and fluid and accordingly the compatible gels were used in combination with cement cap for Gas shutoff jobs in 6 wells. Test results of 4 wells have shown that two of the four wells have been successful. With improved placement technique the jobs are expected to be more successful.
Monohull Vessel for Subsea Well Intervention
Authors: Vorkinn P. B. , Friedberg R. , Hoemsnes L.
Published: December 2007

This paper describes a conceptual design of a subsea well intervention unit. The Intervention Service Unit (ISU) is a fit for purpose monohull vessel.

Focus on operational efficiencies and cost reduction has been important in the design phase, while prioritizing solutions, which minimize health, safety and environmental (HSE) exposure.

Scope of work for the ISU is wireline operations, coiled tubing and pumping services, subsea equipment installation and maintenance, well clean-up, testing and coiled tubing drilling.

High operability in harsh environment, such as the northern North Sea, is a major design parameter.

The general section of the paper explains the basic engineering execution and the overall specification structure of the concept, from the generic Functional Specification through the more detailed Building Specification.

Some of the challenges which were identified and the unique solutions developed, are described. This includes work over open water and at elevated levels, splash zone issues, handling of heavy loads on a moving structure, amongst others.
Formation Treating with Coiled-Tubing-Conveyed Straddle Tools
Authors: Giroux Richard , Hoffman Corey , Wilson Paul
Published: December 2007

In many wells it is advantageous, both economically and operationally to perform stimulation techniques using coiled tubing. More often than not this process will require that the zone of interest be isolated for the treatment to be effective. Several basic means of isolation are available depending on whether the application requires intervention through tubing or into a monobore, or "tubingless", completion. These basic tools require some form of pipe manipulation to set and retrieve, which in straight holes presents little difficulty, but in deviated wells becomes problematic. As the deviation from vertical increases and eventually reaches horizontal, tool manipulation becomes increasingly difficult and eventually impossible.

To address this problem in highly deviated wells a new generation of downhole straddle tools has been developed which requires no pipe manipulation to set and retrieve. These tools, called Fluid Velocity Set devices, use fluid pressure build up created when pumping through a nozzle to activate and relaxation of that pressure to deactivate a tool. Two distinct types of tool have been developed: Inflatable straddle packers for through tubing applications, which can be inflated to seal in an I.D. up to 2.5 times larger than the running O.D.Mechanical straddle packers for monobore applications, which have a running O.D. small enough to pass through standard tubing mounted accessories, such as landing nipples and sliding sleeves, and set in the tubing I.D.

This paper will discuss the advantages and disadvantages of commonly used isolation methods and will detail the design, development and testing of these new tools. Using recent field tests the authors will illustrate that this type of tool provides a functional and cost effective method of isolating zones in highly deviated and/or horizontal well sections.
Innovative Solution to Prevent Coiled Tubing Operational Failures Caused by Human Errors
Authors: van Adrichem Willem P. , Adnan Sarmad
Published: December 2007

The impact of an operational failure during a coiled tubing (CT) intervention is typically more severe than that of other failures because of the nature of the activity. Failure of the tubing or any component of the well intervention process in a live well scenario can compromise well control and/or the safety of personnel. Statistics on causes of CT operational failures (OFs) indicate that a majority of these failures can be attributed to human error. Incorrect actions, or the lack of action, are very difficult to predict and therefore a major challenge to control. Running CT in and out of the well involves a high degree of human interaction and human fatigue, and short periods of inattention during this process are not uncommon.

During such activities, inattention can lead to actions that damage, kink or part the CT, with potentially disastrous results. Other causes for OFs include unintentional tensile overloads, overpressuring, runaways and other such events. An electric over-ride device, developed for installation in the hydraulic circuitry of a CT unit, allows setting of limits on all pertinent operating parameters of the injector head. Setting equipment limits for weight, velocity and pressure gives the operator an extra set of eyes, greatly increasing operational safety and efficiency of the treatment.

This paper discusses OFs caused by human error and presents case histories that contributed to the conclusion of which parameters require control. The over-ride device used in the control process is discussed in technical detail, and case histories demonstrate the impact of its use on overall safety and service quality in the CT industry.
Case Study of Estimated vs. Actual Coiled Tubing Forces
Authors: Lizcano E. , Higuera J. , Crow W.
Published: December 2007

Job planning considerations, including coiled tubing forces, can be critical factors for the type of equipment and the associated risk of a wellbore entry. This paper presents estimated and actual values and explains the useful range of friction factors associated with the wellbore geometry. Emphasis is placed on the situation where equipment and tubular capabilities are close to safe operating limits. Operational alternatives are discussed which can help manage the risk and aid contingency planning.

Outline Operations plan to perform acid stimulation using 1.75" OD QT900 coiled tubingEstimated forces were 34,000 lbs at TD of 15,400’ MD (with flowing well and brine in CT)Survey shows average DLS of 1.25 down to 15,000’ with a maximum of 4.3 DLS at 8600’Show excel plot of well trajectory in 3D for azimuth changeWellbore entry with periodic weight checks up to maximum of 58 Mlbs pull at 12000’Attempted loading the well with fluid to increase buoyancy without success.Used friction reducer mixed at 5% by volume to decrease friction, but obtained only 10% reduction (or 7 Mlbs).Well entry planned with new friction factors to match the actual weight checks and using QT110 CT with friction reducer.Not many wells with this type of azimuth change in the BP data set.Should consider this limit to well servicing during drilling operationsLow IPR did not justify another cleanout attempt, but perforated upper intervals instead.

Need data from follow up operation (if any) to show the effect of change in planning procedure.

Possible mathematical factor applied to azimuth change to increase friction factor for future CT force estimates.
Coiled-Tubing Wiper Trip Hole Cleaning in Highly Deviated Wellbores
Authors: Walker S. , Li J.
Published: December 2007

Wiper trips are the current field practice to clean the hole for coiled tubing drilling or sand clean out operations. A wiper trip can be defined as the movement of the end of the coiled tubing in and out of the hole, a certain distance. In order to clean the solids out of the wellbore, a proper wiper trip speed should be selected based on the operational conditions. There is no previously published information related to the selection of the wiper trip speed. In this study, numerous laboratory tests were conducted to investigate wiper trip hole cleaning and how the hole cleaning efficiency is influenced by solids transport parameters such as; a) Nozzle Type, b) particle size, c) fluid type, d) deviation angle, e) multi-phase flow effect. The results indicate the following: Compared with stationary circulation hole cleaning, the use of the wiper trip produces a more efficient clean out.For a given operational condition, there is an optimum wiper trip speed at which the solids can be completely removed.Nozzles with a correctly selected jet arrangement yield a higher optimum wiper trip speed and provide a more efficient clean out.The hole cleaning efficiency is dependent on the deviation angle, fluid type, particle size, and nozzle type.

Correlation's have been developed that predict the optimum wiper trip speed and the quantity of solids removed from and remaining in the wellbore for given operating conditions. The wiper trip provides an advantage for hole cleaning and can be modeled to provide efficient operations.
Development of Computer-Controlled Hybrid CT Drilling Units
Authors: Ewen Robert , Mackay Kevin , Shepard Frank
Published: December 2007

This paper describes the development and design of a computer controlled hybrid coiled tubing unit used for workover, re-entries, casing exits, coiled tubing under-balanced drilling, running & cementing liners and logging & perforating. Key components of the unit were a purpose-built bottom hole assembly and a companion control cabin.

The goal was a "fly by wire" control cabin with no hydraulic lines and a minimum number of hydraulic hoses linking the equipment. All equipment on site was to be controlled from a central location. The focus was to construct an environmentally friendly unit requiring minimum crew size but without impacting safety.
Risk-Based Well Control Planning: The Integration of Random and Known Quantities in a Computerized Risk Management Tool
Authors: Nilsen Thomas , Sandøy Malene , Rommetveit Rolv , Guarneri Alberto
Published: December 2007

Site-specific challenges related to water depth, geological and environmental conditions, rapid technological development and increased demands with respect to cost effectiveness and environmental consciousness are all factors that impact the uncertainty picture related to drilling and well operations. Thus risks related to undesirable outcomes such as kick and blowout are also influenced. It is however questionable whether the ruling practices for use of quantitative risk analyses in planning of the operations keep up with this development. As the nature of the operations change drastically, use of overall statistics from earlier incidents hardly provides a satisfactory basis for decision making. Such statistics does not reflect the exposure of the specific well to the various kick and blowout mechanisms or the effect of measures introduced to reduce the probability of these mechanisms to occur. KickRisk, a new risk analysis tool with focus on kick and blowout is developed in order to improve the basis for risk-based well control planning. The idea behind this tool is a more detailed system modeling, which enables the planning to include more well- and operation-specific information in the analyses and to obtain a more differentiated risk description. Uncertainty is expressed through probabilities related to factors at a detailed system level and is propagated in kick and blowout probabilities through the logic of the model structure. The intention of this paper is to discuss the requirements for risk analysis methods with respect to kick and blowout in well planning and how these can be met in practice. The principles of the new tool KickRisk are described and the experiences from case studies on real wells are presented.
Use of Flow-Pattern-Based Models for Interpreting Oil-Water Flow in Production Logging
Authors: Kabir C. S. , Hoadley S. F. , Kamal D.
Published: December 2007

Production logs (PL) are often run to diagnose unwanted water production before seeking remedial actions. The diagnosis, involving accurate estimation of slip velocity during two-phase oil-water flow, is a precursor to taking successful corrective measures.

This study entails finding the most reliable holdup or slip-velocity model by examining 78 production logs, run in Kuwait’s Greater Burgan field. We observed that most models provided the desired level of accuracy when the downhole results were compared with those measured at surface. The notion of direct use of flow-pattern maps in PL interpretation is introduced in this work.
Underbalanced Operations Continue Offshore Movement
Authors: Hannegan Don M.
Published: December 2007

About 20% of the world's known offshore reserves of natural gas and oil are economically undrillable with today's conventional tools and technology. Major barriers to conventional methods and equipment must be overcome to economically drill for these vast reserves. The barriers to conventional deepwater drilling methods are: Narrow margin between the formation fracture and pore pressures requiring excessive casing programs and larger, more expensive rigs to drill.Depleted reservoirs relative to water depth where hydrostatic head of conventional mud and cuttings cause gross overbalanced and resulting damage to well productivity.Shallow water flow hazards.Limited ability to adjust equivalent circulating density while drilling ahead.

The tools and technology associated with underbalanced (UB) drilling are seen as key to economically and safely drilling into these reserves. Further, it is expected that by the end of this first decade of this millennium, offshore applications of underbalanced drilling tools and technology will play a profound role in the industry, particularly in deeper waters.

For example, to deal with the conventional drilling barrier described in Item 1., above: The ability to drill offshore with lightweight fluids, perhaps while incurring annulus pressure at the surface in the marine riser (if drilling from a floating rig) or surface BOP stack (if drilling from a jack up), is seen as a viable and attractive method for overcoming this conventional overbalanced drilling barrier. The objective in many cases may not be to achieve true underbalance, but to drill nearer balanced than one would wish to do if drilling conventionally.

For dealing with the barrier described in Item 2., above: Dual density (aka dual gradient) deepwater drilling methods provide an additional attractive option. In the application of this technology, a state of underbalanced is not achieved or desired, but the tools and technology one normally associated with underbalanced drilling are required to practice this technology.

For dealing with the barrier described in Item 3., above: Use of a subsea rotating control head is an option. In this case, one considers shallow water flow hazards as a well control issue and tools up to deal with it accordingly.

For dealing with conventional drilling barrier described in Item 4., above: Underbalanced operations require specialized surface equipment. In the case of dual density drilling, specialized subsea equipment. E.g., Rotating diverter control head, choke manifold, fluids separation and a means of dealing with produced hydrocarbons. The addition of this equipment usually provides at least one and sometimes several additional methods of adjusting equivalent circulating density while drilling ahead.
Jet Drilling Tool: Cost-Effective Lateral Drilling Technology for Enhanced Oil Recovery
Authors: Buset P. , Riiber M. , Eek Arne
Published: December 2007

The paper describes a new coiled tubing conveyed drilling technique, were several new well bores are jet-drilled perpendicular from the mother well and into the reservoir formation. This technology is targeted for Enhanced Oil Recovery (EOR) in both existing and new field developments. The objective is to improve the production profile around the mother well, by penetrating the damaged skin zone, and connecting to possible hydrocarbon pockets left behind in the reservoir.

The Bottom Hole Assembly (BHA) is configured to jetdrill several slim laterals, all in one coiled tubing (CT) run. This through tubing operation has the potential to create up to ten, 50 m long, and 1–2 in. diameter laterals at the exact desired depth in the mother well. The BHA consists of two main parts; a casing drilling machine and a high-pressure hose and jet-nozzle. The hose is spooled from the BHA as the lateral is drilled into the formation.

The main issues presented in the paper are: The new jet tool functional characteristicsThe theoretical aspects of jet drilling; penetration mechanisms and self-induced nozzle pull forceLaboratory experiments (confirmation of theoretical models)The jet drilling effect on improved well production (production simulations).

The technology is an attractive substitute or supplement to acid and proppant fracturing, perforating services and conventional sidetrack drilling.
Practical Methods to High-Grade Infill Opportunities Applied to the Mesaverde, Morrow, and Cotton Valley Formations
Authors: Hudson J. W. , Jochen J. E. , Spivey J. P.
Published: December 2007

Several gas basins within North America are under-going a period of infill drilling in order to supply the increasing demand for natural gas. It is not uncommon for an operator to have hundreds, if not thousands of infill candidates from which to choose. Is there a practical way to high-grade infill locations within a particular basin or field? This paper presents several practical techniques to high-grade infill drilling opportunities when faced with large data sets and little time. We will present results for the Mesaverde in the San Juan Basin, the Morrow in the Permian Basin, and the Cotton Valley in east Texas.

We calculated the infill potential for each of the three example formations. Based on our experience, we have found that comparisons between actual and predicted individual infill well performance can vary significantly. Therefore, ranking infill candidates on predicted individual well performance may not necessarily yield the best overall results. Poor wells, predicted to be good wells, may still be drilled and good wells, predicted to be poor wells, may not be drilled at all.

Alternatively, when considering an infill drilling program as a whole, we have found that the predicted performance for the group can be quite accurate. In this paper, we will present a method to divide a basin or field into smaller areas and predict the distributions of infill performance as a group for the smaller areas, rather than individual wells. We will then present two methods to rank the small areas to achieve the most economic results. The first method ranks the areas based on the average of the distribution. The second method uses decision tree analysis to calculate a typical infill well in an area using the P10, P50, and P90 values from the distribution.

We considered actual recent drilling programs in each of the three formations, used the above techniques to eliminate predicted uneconomic wells, and compared the actual to predicted drilling program results. We found that the finding and development costs were lower, return on investment was higher, and the success ratio was higher when the techniques presented in this paper were used to high-grade drilling opportunities.

The results of a study applying this analysis technique can be used when budgeting and planning near- and long-term drilling programs.
Produce or Plug? a Summary of Idle and Orphan Well Statistics and Regulatory Approaches
Authors: Thomas Keith T.
Published: December 2007

It is an obvious statement of fact that every well drilled will reach the end of its productive life. When the well reaches that point, plugging is the appropriate and environmentally sound solution. Unfortunately, there are a large percentage of wells which are idle, not because their resources have been depleted, but because they have become unprofitable due to low product prices or high production and environmental compliance costs. At this time the latter two are more likely. Most idle wells do not pose an environmental threat. Idle wells could potentially provide the states and the nation with much needed domestic production. It is in the best interest of the oil and gas states to insure that no well is prematurely plugged. The states recognize the economic potential of idle wells, but also realize that many of these wells represent potential liability. The responsibility of plugging orphan wells -- those where the operator has gone out of business or is insolvent -- falls on the states. For some states this is a large burden. Though orphan wells are the greatest burden, the states are usually responsible for monitoring the status of all idle wells. Facing this challenge, the oil and gas states have developed some effective solutions.
Simulation of Naturally Fractured Reservoirs with Effective Permeability
Authors: Sutopo Sutopo , Arihara N. , Sato K.
Published: December 2007

Proper modeling and simualtion of naturally fractured reservoirs is one ofthe most important and challenging issues in reservoir engineering. A dualporosity or dual permeability approach is applied in simulation when fracturesform a flow network. On the other hand, single continuum model, where thefracture system is represented by effective permeability, is commonly used iffractures are discrete or disconnected. Focusing on the letter case, this paperpresents a numerical model that incorporates full tensor permeability in eachgrid block to accurately simulate behaviors of discretely fractured media.

We formulate a flux continuous model using the mixed finite volume elementmethod where the pressure equations, expressed as two coupled first-orderpartial differential equations for pressure and velocity, are solvedsimultaneously. This minimizes the numerical errors occurring in standardmethods caused by differentiation of pressure and then multiplication by roughcoefficients. The saturation equation is to be solved by an implicit pressureexplicit saturation approach.

Numerical examples of simulating flow in fractured reservoirs are presentedto demonstrate the performance of the proposed simulator. The reservoir modelsfor simulation are two-dimensional and include regularly or stochasticallydistributed discrete fractures. Effective permeabilities calculated by thecomplex variable boundary element method are assigned to grid blocks. The samemethod is used to obtain reference solutions of the tracer propagationperformance in the five-spot pattern. The examples validate importance ofaccurate representation of the full tensor permeability for simulation ofnaturally fractured reservoirs.
Optical Fiber Logging System for Multiphase Profile Analysis in Steam Injection Wells
Authors: Ruan Hang , Chen Yaosheng , Liu Yanjing , Jiang Liping , Claus Richard O.
Published: December 2007

In a steam injection well, the downhole parameters such as temperature, pressure, steam quality and steam flow indicate an accurate multiphase profile, which is important for oil acquistion and reservoir management. The downhole logging systems based on optical fiber sensors for simultaneously measuring the four parameters of steam are reported in this paper. The constructive details and procedure for sensors alignment are described. Few examples of logging applications are discussed.
Petroleum Engineering Professional Registration into the 21st Century
Authors: Wines G. Bing
Published: December 2007

Professional Registration in the United States is continuing to become more important for Petroleum Engineers. It has seen some drastic changes since its implementation unto the national scene in 1973. The requirements to become registered have gradually become stiffer. An engineering, math or science degree is fast becoming the norm to be a licensing engineer. Continuing Education requirements are also being implemented.

The Petroleum Professional Registration Exam is changing. As we enter the 21st Century, the PE Exam is being offered as a full multiple choice exam. The format of the exam is evolving towards an exam that can be administered eventually via the computer. Tomorrows average Petroleum PE examinees will be better qualified than their counterparts of previous years. Projections are made for the next century.