bluuebunny/crossref_metadata_2025 huggingface dataset:
Three Dimensional Seismic Survey in Ogata, Japan
Authors: Minegishi M. , Aoki N. , Higashinaka M. , Tamura Y. , Amano H.
Published: December 2007

A 3D seismic survey was conducted in Ogata area, one of Japanese mature oil fields. The survey was aimed to obtain a basic data set, which is useful for studying the effects of irregular data acquisition geometry, and to provide the precise information on the subsurface structure for finding additional reserves. The survey area was previously the second largest lake in Japan and has been changed to rice fields after reclamation. Few difficulties in seismic data acquisition were expected and dense regular data acquisition geometry was planned to use in the survey. However, acquisition work encountered many hazards because a lot of unexpected constraints came from the reclaimed land. Moreover, obtained shot records showed the very complex nature of seismic wave fields. Especially, strong ringing waves masked weak reflection signals. Spatial variation of these ringing waves was investigated and the origin was modeled as critical refraction of multiple reflected waves within a very thin surface layer. Those results can provide valuable knowledge for seismic survey in areas with similar surface conditions. In seismic data processing, these ringing waves were successfully suppressed at the earlier data processing stage by FK filter in common shot and receiver domains followed by deconvolution. After this suppression, remaining data processing became more effective and gave a precise depth image. Various analyses to the obtained processing vintage such as coherency cube and attributes revealed the existence of minor faults precisely, which were not recognized previously. These could give a new interpretation of the area. As a result, the data set can be very useful for the evaluation of irregular data acquisition geometry as well as the exploration in the area.
Casing Failure In Steam Stimulated Wells A Case History Of The Guapo Field
Authors: Bissoondatt J.C.
Published: December 2007

Casing failure in production wells stimulated with steam presents economic and technical limitations in the application of the method. Completion of a steam injection well must be designed so that saturated steam can be injected into an oil reservoir at the desired rate, pressure or temperature and heat content. During the injection of steam, heat is lost to the surrounding well bore, equipment and the earth due to the high temperature of the steam. It is therefore desirable to design the completion so that heat loss is minimised and the casing temperature is kept low enough to prevent casing damage whilst ensuring that most of the steam goes into the productive formation. productive formation

Introduction

The Upper Cruse sands of the Guapo Field have been under thermal exploitation, 'Huffing n Puffing', since August 1968 when a pilot project was initiated using a portable steam generator. Early results from the pilot indicated that economic production could be obtained from these viscous (1600 cp at 100 deg. F) oil reservoirs as production rates were increased from 15 bopd up to 100 bopd and in some cases up to 200 bopd.

As a result of the successful pilot a major expansion programme was vigorously embarked upon. Over 100 programme was vigorously embarked upon. Over 100 wells were drilled from the period mid 1971 to present and fixed generators installed.

After 3 years of 'huffing n puffing' it was found that many of the wells had parted casing and damaged gravel pack liners. To date, 15 casing and 50 gravel packed liner failures have been positively identified. packed liner failures have been positively identified. The text that follows outlines some of the procedures adopted and problems encountered procedures adopted and problems encountered and suggests principles that should be taken into account when designing steam injection - production wells of this nature.

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Distinguishing Between Oil and Gas in Shaly Sands - A Case History
Authors: Alleyne N.A.B. , Harper W.N.
Published: December 2007

A primary logging technique used for distinguishing between oil and gas in reservoirs is the overlaying of the Compensated Neutron Log (CNL) Compensated Formation Density (FDC) Log. Whereas this technique is very reliable in clean sands, in shaly sands, however, the log must be corrected for the effects of shale. Methods of correcting the CNL and FDC logs for the effects of shale have been devised, but though these methods are very reliable, they are neither suitable for use at the well site nor for use in quickly distinguishing between oil and gas. Amoco Trinidad Oil Company (ATOC) adopted a method for correcting for the effects of shale on the CNL and FDC Logs called V SHALE ANALYSIS. This method is a modification of a more sophisticated analysis and field tests have proven it to be reliable. The method is suitable for use at the well site for the quick differentiation between oil and gas bearing zones.

Introduction

Many of the reservoirs in the oil fields of Trinidad, West Indies (Fig. 1)occur in sandstone formations which contain varying quantities of shale. In this respect, the reservoirs in the oilfields off the East Coast of Trinidad which are being operated by ATOC are no exceptions. Since commencing operations, ATOC has developed three oil fields, the Teak Field, the Samaan Field, and the Poui Field. Of these, the Teak Field, which is infamous for its sand production problems, was the first to be developed. Generally, the reservoirs in the Teak Field were relatively clean sands and, as a result, overlaying the Compensated Neutron Log (CNL) with the Formation Density Log(FDC) gave very clear and reliable distinction between oil and gas zones. The Samaan Field was discovered after the Teak Field and it differed from the Teak Field in that its sands were generally shalier. The shaly nature of the sands in the Samaan Field had an adverse effect on the technique of overlaying the CNL and FDC Logs to distinguish between oil and gas bearing zones. The need therefore arose for a method of correcting the CNL and FDC Logs for the effects of shale. Methods were available which gave adequate correction for the effects of shale on these logs, but they were unsuitable for the quick determination of hydrocarbon contents at the well site, since they either required tedious hand calculations or utilized a computer. ATOC therefore adopted a method called VSHALE ANALYSIS to correct for the effects of shale on CNL and FDC Logs. V-Shaleanalysis is a modification of a more sophisticated computer method called SARABAND 1.

This paper summarizes the procedure of the V-Shale Analysis and also describes the result which ATOC has had with it.

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A Coiled Tubing-Deployed Slow-Rotating Jet Cleaning Tool Enhances Cleaning and Allows Jet Cutting of Tubulars
Authors: Connell Mike , Courville Perry , Tucker James
Published: December 2007

Tubular restrictions from scale buildup can significantly reduce hydrocarbon production, and buildup must be removed to restore the production capacity of a well. Although scale buildup is a global problem, the material composition and characteristics of scales can vary drastically, even within the same field, making most tools on location insufficient for scale removal. A customized jet cleaning tool has recently been developed to address the problems associated with tubular cleaning operations.

Traditional jet cleaning tools are insufficient for removing scale buildup because they do not reliably control jet dwell time. Jet dwell time is the relationship between the difficulty of tubular cleaning and the time required for scale removal. Jet dwell time increases with an increase in the hardness of the buildup material. Ability to control dwell time is a measure of cleaning efficiency. A new, slow-rotating jet cleaning tool can help optimize jet dwell time for cleaning operations without repetitive cyclic effects on a coiled tubing (CT) workstring.

The slow-rotating jet cleaning tool can also be used for cutting tubulars. Previously, tubulars were cut by mechanical, explosive, or chemical methods, and CT was used to deploy positive-displacement motors (PDM's) and pressure-activated firing devices (used for rotating the mechanical cutters and initiating the firing sequence in explosive or chemical cutters, respectively). For many through-tubing applications, traditional cutting methods created significant safety risks and obstacles such as long bottomhole assemblies, increasing service costs. With its capability to control jet dwell time and pump abrasive fluids, the new jet cleaning tool can reduce the safety risks and the costs associated with traditional cutting methods.

This paper discusses the design and application of the slow-rotating jet cutting tool, and provides case histories of the tool's use in removing scale and production buildup on tubing walls. The paper also discusses application of the tool for performing through-tubing cuts.
Predicting Core Porosity using Wire-Line Logs at Dagger Draw Field, SE New Mexico
Authors: Balch R. S. , Weiss W. W. , Wo S. , Welch D.
Published: December 2007

At Dagger Draw it is difficult to arrive at reliable estimates of total pore volume in the vuggy dolomitic reservoir. Correlating wire-line logs to core porosity using a multi-layer perceptron neural network (MLP) generated a "ground truth" porosity estimator for the reservoir. Well logs in the field include CAL, DRHO, GR, LLD, LLS, MSFL, NPHI, PEF, RHOB, and values of DPHI, PHI-L (liquid phase porosity) and PHI-G (gas phase porosity) were calculated. Log values were aligned with the center point of laboratory analyzed core samples in five cored wells with a total of 21 cored sections. Neural network solutions generated using four of the five wells to blindly predict the fifth well validated results. Each well was excluded in this fashion, for a total of five tests.

The resulting correlation tool, if applied at hundreds of wells within the field without core data, would provide the basis for geostatistically derived pore volume maps.

Fuzzy ranking was used to evaluate the usefulness of individual logs for correlating with core porosity, and also indicated that the problem was complex, and guided architecture design for the MLP. The seven best logs were used as inputs for the MLP, and results show that the MLP can describe the complex relationships between the wire-line data and core porosity. Regression relationship were able to predict the excluded wells at up to CC=0.80. These results are a great improvement on the linear equations previously used for estimating porosity at the Dagger Draw and better predictions are expected, as the process is refined and neural network algorithms are improved.

The use of artificial intelligence to generate core porosity data using only wire-line log data can provide data that could only be attained previously using expensive cores.
Integrated Identification of Possible Compartmented Gas Reservoirs: A Case Study
Authors: Shenawi Shamsuddin H. , Howard William E. , Rowland Bret , Lara Alejandro L. , Zacarias Moises C. , Chavez Gustavo M.
Published: December 2007

This paper presents a method to identify and calculate hydraulically connected gas reserves in compartmented gas reservoirs. The 3-D seismic amplitude analyses and edge detection indicate the possible compartmented sands in the same geological flow units identified in this study. Petrophysical properties of adjacent wells also change abruptly that indicate the deltaic nature of sand deposition in Frio Marine and Frio Non-Marine formations.

The "material balance" method to calculate original gas in place (OGIP) and remaining gas reserves utilizes a plot of p/Z values versus cumulative gas production. The assumption is that all wells should drain from the hydraulically connected tank-type gas sand body. The isolation of wells draining from different sand bodies is important to determine the correct OGIP for each sand body. Therefore, measured shut-in reservoir pressures were plotted against time for each geological flow unit. Plotted pressure profiles for each well made it possible to identify wells draining from a common sand body. Wells draining from a single gas pool had a uniform pressure decline. However, the well that produced from a different gas pool had a distinct pressure decline trend. Several wells encountered initial reservoir pressures even though the corresponding formation that was completed in was put on production 20 years ago.

This paper provides three examples of integrating 3-D seismic amplitudes, production bubble maps and pressure analyses to differentiate hydraulically connected sand bodies. The material balance calculations provide accurate OGIP and remaining gas reserves. This method identifies significant volumes of remaining gas reserves that lead to reopening of shut in gas wells utilizing minor workovers.
Improving Hydraulic Fracturing Results Using Log Saturation Data
Authors: McNaughton Robert T.
Published: December 2007

A new hydraulic fracture screening method has been developed based on quantitative analysis of the mobile oil saturation in the target zone. The traditional selection process was based on analysis of low productivity wells, followed by extensive fracture modeling of leak-off parameters and rock properties. The new screening method defines the best pay zones and uses the saturation profile to govern the size of the fracture treatment.

This method was developed during a 10-acre infill-drilling program on the Central Vacuum Unit during the mid 1990s. Most of the producers were initially stimulated with large, one stage acid treatments. Production declined soon after completion and fell below the levels of offset producers. Texaco analyzed the open-hole logs and discovered a consistent pattern of low in-situ water saturation in the upper San Andres. Log analysis clearly indicated that the infill well production should be much better than the offset wells. Three of the new wells were successfully fracture treated across the entire San Andres interval with excellent results. However, many stimulation candidates were offset by wells producing high water volumes. The new screening method indicated that the upper San Andres should produce nearly water-free after fracturing. The design process also showed that smaller fracs would have substantially better economics and would ultimately produce as much or more reserves as large fracs.

Texaco fractured eighteen more wells in the upper San Andres. Oil production dramatically improved but water production was often unchanged. The new screening method allowed the development of additional reserves that were not recoverable under earlier practices.
Investigation of Well Productivity in Gas-Condensate Reservoirs
Authors: El-Banbi Ahmed H. , McCain W. D. , Semmelbeck M. E.
Published: December 2007

The productivity of the wells in a moderately rich gas condensate reservoir was observed to initially decrease rapidly and then increase as the reservoir was depleted. All wells in the field showed the same response. Compositional simulation explained the reasons for these productivity changes.

During early production, a ring of condensate rapidly formed around each wellbore when the near-wellbore pressures decreased below the dew point pressure of the reservoir gas. The saturation of condensate in this ring was considerably higher than the maximum condensate predicted by the PVT laboratory work due to relative permeability effects. This high condensate saturation in the ring severely reduced the effective permeability to gas, thereby reducing gas productivity.

After pressure throughout the reservoir decreased below the dew point condensate formed throughout the reservoir, thus the gas flowing into the ring became leaner causing the condensate saturation in the ring to decrease. This increased the effective permeability of the gas. This caused the gas productivity to increase as was observed in the field.

There were also changes in gas and condensate compositions in the reservoir which affected viscosities and densities of the fluids. These effects also impacted gas productivity.

This work is another step forward in our understanding of the dynamics of condensate buildup around wellbores in gas condensate fields.
Adapting High Permeability Leakoff Analysis to Low Permeability Sands for Estimating Reservoir Engineering Parameters
Authors: Craig David P. , Eberhard Michael J. , Barree Robert D.
Published: December 2007

The modified Mayerhofer method has been proposed for estimating permeability from the pressure falloff data in moderate and high permeability reservoirs before hydraulic fracture closure following a diagnostic fracture injection test. Applying the modified Mayerhofer method in low permeability sands, however, requires understanding of the closure mechanism, which is identified with G-function derivative analysis of the before-closure pressure falloff data. This paper demonstrates how G-function derivative analysis and the modified Mayerhofer method are used in conjunction to estimate reservoir permeability in low permeability reservoirs.

Numerous applications of G-function derivative analysis have shown the characteristic closure mechanisms—normal, pressure-dependent leakoff from fissure opening, fracture-height recession, fracture-tip extension, and changing compliance—all result in distinctive specialized plots using the modified Mayerhofer method. When the two methods are used in conjunction, G-function derivative analysis provides a means for identifying the falloff data that can be used to estimate permeability and fracture-face resistance without violating the assumptions of the modified Mayerhofer method. Field cases are included to demonstrate that reasonable estimates of reservoir permeability in low permeability reservoirs often can be obtained from the before-closure pressure falloff following a diagnostic fracture injection test.
Mini-Injection Tests Provide Inflow Performance Characteristics for Oilwells
Authors: Myers Donald L.
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

When an oil well is to be put on production with artificial lift, the inflow performance characteristics of the well are sometimes unknown. Analysis of the pressure transient response to a short-term injection test can provide this information. Imperial Oil Limited (IOL) used the technique successfully to obtain data for the initial selection of equipment on a number of recompleted wells in the Judy Creek field.

Introduction

Recently, a number of old, suspended wells in the Judy Creek field had to be reactivated in order to carry out the programmed reservoir depletion strategy. These wells required artificial-lift equipment, but little was known about the production capacities of those wells since they had not produced for several years and reservoir conditions had changed considerably. In addition, most wells were recompleted over new or additional zones which made data on their original productivities even more obsolete. To sensibly select lifting equipment up-to-date information on the well characteristics had to be obtained.

This paper describes a simple field test and subsequent analytical procedure which IOL applied to obtain inflow performance characteristics for oil wells. It shows how the analysis of the pressure transient response to a mini injection test provided the necessary data, including permeability thickness, skin factor and inflow performance relationship. These data then served as a basis for the selection of artificial equipment for the new well installations. IOL used the test also to check the characteristics of existing pumping wells which had failed and to evaluate the incentive for stimulating wells. Examples of the application of the test are given.

THEORY

The test is based on the well-known principles of pressure buildup and falloff principles of pressure buildup and falloff analysis as described by, e.g., Matthews and Russell. When a well operates with a constant injection or production rate, the surrounding reservoir area maintains a certain pressure profile (Fig. 1). The pressure at the wellbore profile (Fig. 1). The pressure at the wellbore radius, rw, is the bottom-hole injection pressure, Pinj, and this pressure decreases, with the Pinj, and this pressure decreases, with the distance from the wellbore to the reservoir pressure, Ps, at the drainage radius, re. pressure, Ps, at the drainage radius, re.
Good Coiled Tubing Welds, Properly Managed, Do Not Break
Authors: Van Arnam W. D. , Smith D.
Published: December 2007

Butt welding of coiled tubing performed routinely in both new and used tubing extends life or increases application versatility of existing strings. Welds are commonly made to replace overly fatigued sections, remove mechanical damage, extend string length, and attach special application strings or tools to work reels and repair tubing imperfections. Properly designed and executed butt welds provide the same load bearing properties of the surrounding tubing. The weld integrity is verified by non-destructive testing, insuring sound joints. The fatigue properties of the weld must be understood and properly managed. This has resulted in an extremely successful record for butt welds placed in coiled tubing for field application.

The paper documents the steps required to insure the best weld quality is being placed into a string of coiled tubing. Data on properties of welds from manual and machine welds, in both new and used tubing verify the load carrying capability of the welds. The down rating of fatigue life and potential corrosion implications are handled through continuous string management. The field experience of butt welds performed in both factory and field environments are reviewed. Results indicate the clear cost effectiveness of currently available, properly installed butt welds combined with systematic monitoring by the relevant service companies.
Concentric Coiled Tubing Well Vacuuming Technology for Complex Horizontal Wells in Eastern Venezuela
Authors: Clancy Thomas F. , Falk Kelly L. , Duque Luis
Published: December 2007

Recent activity in developing the heavy oil reserves of the Orinoco belt has required that operators there utilize cutting edge oil field technologies. The latest in pumping technology and horizontal, multi-lateral well completions are being employed and enhanced. Additionally, operators are looking at new approaches to collect and evaluate well and reservoir data. Coiled tubing is also being used to help with some of the well performance issues.

To optimize the performance of long, and/or multi-branch horizontal wells, post drilling clean-up is very important. Historically, this issue has often been overlooked or dealt with ineffectively. Not only is this step important for the resulting production performance, an effective system for accomplishing this can have additional benefits for the downstream facilities during start-up.

The zones of interest in the Orinoco belt are typically poorly consolidated sands, requiring some form of retaining completion. As slotted liners are most common, an effective method of removing solids from inside the slotted liner may also become a requirement.

This paper will discuss the technology of combining concentric coiled tubing with a jet pump to be able to do both the post drilling fluid clean-up and sand removal operations. It will detail the type of equipment used in this application. The paper will also go into specifics of the need for the service in this operation and the corresponding results. Future developments for this technology will also be covered.
Coiled Tubing Drilling – Expanding Application Key to Future
Authors: Crouse P. C. , Crouse Philip C. , Lunan W. B. , Lunan W. Brian
Published: December 2007

Since 1991, technology, people, methodology and commitment have played an integral and prominent role in the advancement, development and application of coil tubing drilling (CTD) as an alternative to conventional drilling systems. Various geological formations have been successfully drilled with coil tubing drilling systems with the CTD technology and methodology being continually adapted, improved upon and evolved from its more traditional uses. This evolution of the coil tubing drilling process is one of the most exciting and fastest growing sections of the coiled tubing industry. Coiled tubing has become a competitive advanced drilling tool when used properly. A very impressive track record has been established in Western Canada where coiled tubing drilling technology has been utilized in mostly shallow gas and oil properties to squeeze profits out of what might normally be considered marginal properties. In this manner the coil has been used as an advanced economic drilling system in both vertical and horizontal wells. In 95% of the operations the wells have been drilled underbalanced to minimize formation damage, reduce drilling problems, and increase the rate of penetration. In many cases this process has eliminated the need for remedial stimulation of the wellbore.
Current and Future Successes in Coiled Tubing Automation
Authors: van Walsum Eric
Published: December 2007

Electronic control systems are one of the enabling technologies that will permit dramatic improvements in the safety, efficiency and reliability of new coiled tubing equipment.

To illustrate how automation can contribute to these advances, examples will be taken from the control systems on one customer’s prototype coiled tubing and pumping units. Safety of operation was enhanced by reducing the number of operators, and placing them in a protected environment. Gains in efficiency were made by automating small tasks in the rig up, and larger tasks in the running of a job. Some contributions were made to reliability as well, in the form of self-diagnostics and soft starts and stops of the equipment.

Implementing the control system was not without its own challenges. The level of control is sophisticated, and the operating environment is harsh and varied. Significant work was required to ensure that the benefits of the control system were not outweighed by its own reliability issues.

The level of automation in coiled tubing applications has advanced from simple control of individual machines to integrated control of whole processes. However, further advances in safety and integration are envisioned.
Friction Pressures of Newtonian and Non-Newtonian Fluids in Straight and Reeled Coiled Tubing
Authors: Willingham Joe Don , Shah Subhash N.
Published: December 2007

As coiled tubing is presently utilized for a multitude of projects in the field, the necessity of estimating the friction pressure of the working fluids in the reeled portion of the coiled tubing string becomes extremely important. Past authors have shown the significant difference in friction pressure between straightened and reeled coiled tubing.

This work discusses the experimental investigation of five different polymeric solutions and one drilling mud in three different coiled tubing sizes. The analysis of the frictional pressure loss data includes the effect of fluid rheology, coiled tubing curvature, and tubing diameter.

The intent of the analysis is to arrive at a correlation describing frictional pressure loss behavior of polymer solutions and drilling muds in reeled as well as straightened tubing.

The experimental setup includes 3000 ft of 2 3/8 in. reeled tubing, 5000 ft of 1 1/2 in. reeled tubing, and 1500 ft of 1 in. reeled tubing. Straightened sections of tubing are also utilized in the setup for comparison and modelling of data.

The experimental results are compared with correlations developed by earlier investigators including Mashelkar, McCann, Ito, and Shah. The analysis of the data led to the development of a new model for polymer solutions and a model for drilling muds. The model for polymer solutions is recommended for power law type, pseudoplastic fluids with a power law index less than one, while the model developed for drilling mud was developed for only one concentration of mud. However, the drilling mud correlation suggests the form that other concentrations of drilling mud may follow.
Friction Pressure Correlations of Newtonian and Non-Newtonian Fluids through Concentric and Eccentric Annuli
Authors: Silva Moises A. , Shah Subhash N.
Published: December 2007

An experimental study has been conducted to investigate the effects of eccentricity on friction pressure loss calculations for drilling and stimulation fluids. Reynolds number in the range of 800 to 100,000 allowed the analysis of friction pressure losses of non-Newtonian fluids in both concentric and eccentric annuli in laminar and turbulent flow regimes.

Analysis of Fanning friction factors as a function of generalized Reynolds number showed that the effects of eccentricity are significant when annular friction pressure losses are estimated. The results demonstrated that the annular pressure losses in a fully eccentric annulus can be as low as 40% of the value in concentric annulus. It was observed that the effect of eccentricity is more evident as the fluid concentration increases. From experimental data obtained in this study, new correlations are proposed to calculate friction pressure losses in concentric and eccentric annuli for laminar and turbulent flow regimes. Though not ideal, these new correlations estimate friction losses in annuli much closer than the previously published equations.
Coiled Tubing: Extending the Reach of Slickline Operations
Authors: McClatchie D. W. , Moon B.
Published: December 2007

The growth of deviated and horizontal well drilling has limited the number of completion options that can be serviced by slickline units. Modifications to conventional slickline plugs, shifting tools, and setting tools have made it possible to run these tools on coiled tubing into highly deviated wellbores where push capabilities are required. Running and retrieval of gaslift valves, however, has remained the sole domain of slickline services. Declining reservoir pressures have more recently led operators to complete some of these high angle wells with gaslift systems fully realizing that not all of the mandrils will be accessible by conventional slickline units, instead requiring expensive rig workovers. By combining conventional slickline gaslift valve tools with coiled tubing and thorough, detailed job design, horizontal gaslift completions can now be economically worked over to optimise well production.
Bridge-Plug Millout With Coiled Tubing—Case Histories
Authors: Durey Daniel A. , Degner Dennis L.
Published: December 2007

Downhole plugs are now commonly used for isolating multistage stimulation jobs. These plugs allow for more timely completion, yet they must also be removed in a timely fashion. This paper discusses how coiled tubing (CT) can efficiently mill out these plugs.

The three case histories in this paper demonstrate the successful use of coiled tubing to mill out bridge plugs set in multistage stimulation jobs. Specifically, each case history provides a brief history of the well, a description of the equipment used to meet downhole and surface needs, and the operating procedure used for the job. The paper concludes with procedures to improve CT millout efficiency.
Pipeline Intervention From a Dynamically Positioned Mono-Hull Vessel via a Flexible Riser
Authors: Alsyed Samih M. , Larsen Henrik A. , Johnston Paul , Schaider Fred J. , Lounsbury Jack , Smith Jeffrey J.
Published: December 2007

After a subsea mudslide near the mouth of the Mississippi River Delta, several sections of production or export pipelines were severed. The pipelines could not be retrieved to surface because they were buried deeply in the mud. Coiled tubing was successfully used to clean and abandon these pipelines insitu under 200-feet of water. The coiled tubing was conveyed through a flexible riser from a Dynamic Positioning mono-hull vessel. The lengths of the four sections of pipeline cleaned were 2400-feet, 1200-feet and 1800-feet with diameters of 8-10 inches.
Running Coiled Tubing in Colombia - Living on the Edge
Authors: Clement C. C. , Duenas J. J. , Junca E. , Ufondu K. O. , Arciniegas O. E.
Published: December 2007

Coiled tubing is used extensively in Colombia as the preferred alternative to conventional workover operations for reasons of costs, logistics, and security. However, wellbore conditions make few jobs "routine" and extensive pre-job planning is required for each well intervention. Even with precautions, unforeseen situations occur that are unique to Colombia.

This paper presents an overview of the types of wells in Colombia. Depths, wellbore schematics, formation interval lengths, fluids produced, etc. are given as background information. Wellbore conditions that affect the use of coiled tubing are detailed to show the difference between Colombia and other areas utilizing coiled tubing.

A complete description of the types of jobs run in Colombia with coiled tubing is presented along with problems encountered while doing these jobs. The types of computer modeling used to design and implement each job are also given. Two actual case histories are used as typical examples of problems encountered on a daily basis during well interventions as well as the solutions to remedy these problems.

A set of guidelines gained primarily through experience in running coiled tubing in Colombia are presented and may help others encountering similar wellbore conditions in other areas of the world. The concluding section of the paper lists the areas requiring more technological advances for running coiled tubing in Colombia.
The Effect of Corrosion in Coiled Tubing and Its Prevention
Authors: Van Arnam W. D. , McCoy T. , Cassidy J. , Rosine R.
Published: December 2007

Unpredictable coiled tubing (CT) service life is not acceptable in the CT industry and is not tolerated by the customer. Experience shows that service life becomes unpredictable without adequate tubing maintenance programs that include corrosion prevention. Therefore, monitoring and maximizing CT service life requires effective corrosion control on both inside and outside CT surfaces from the time the tubing string is milled until it is retired. Corrosive degradation of CT can result from contact with the atmospheric environment, pumped fluids, and production fluids. Corrosion, especially localized corrosion, must be prevented because it can greatly affect tubing life by initiating premature fatigue cracking and growth during cycling. Additionally, corrosion can reduce usable tubing strength and pressure integrity.

This paper discusses effective preservation and inhibition programs instituted at the tubing mill, service centers, and in the field. In addition, electrochemical corrosion-rate data for as-milled and cycled CT is presented. Linear-polarization resistance and Tafel-curve generation were used to derive general corrosion-rate data for new and cycled CT-90 and CT-100 in various common oilfield fluids, including a stimulation fluid. These tests suggest that CT corrosion tendency is not significantly accelerated as a result of cycling, except at high temperatures. Additionally, the paper presents high-pressure fatigue data from tests performed on CT-90, comparing fatigue life in water and in inhibited 15% hydrochloric acid (HCl).
Coiled Tubing Inspection and Tubing Management: A Case Study
Authors: Toye Terry N. , Pantaleo Tony , Rheinlander Mark D.
Published: December 2007

Coiled tubing (CT) is increasingly used in completion and workover applications, especially as a deployment method for acid and other corrosive materials. The occurrence of internal wall loss and external pitting has become more common, especially if proper tubing management is not followed. Not only is there internal wall loss associated from the use of corrosive materials, but also external pitting from severe downhole environments as well as surface environments. The recent industry down turn has reduced the utilization of coiled tubing strings. This sometime causes deterioration of the metal quality through external and/or internal corrosion, particularly when good maintenance procedures are not followed, and strings are not properly protected from the environment. This becomes costly, as strings are unable to be used to their full life potential or when a job failure occurs because of poor string management.

This paper presents case data demonstrating that the use of CT inspection and proper tubing management can avoid or reduce future job problems. The use of the described techniques and good pipe management will in turn reduce safety problems, and lost revenue due to pipe failures and shortened string life.
Vibration Analysis for Coil Tubing Drilling in Prudhoe Bay
Authors: Flynn T. S. , Jahn B
Published: December 2007

Coil Tubing Drilling substantially lowered the cost for drilling Prudhoe Bay sidetrack wells. The program was nevertheless fraught with MWD (Measurement While Drilling) instrument failures. Downhole tool damage happened so often it was considered routine. Generally there was agreement that excessive vibration played a key role in downhole tool damage. Without causes the only solution was to build more durable tools.

To monitor and record downhole vibration, a DDS collar (Drill String Dynamics Sensor) was added to the BHA. The DDS tool was capable of recording lateral, torsional, and axial accelerations. It also incorporated spectral frequency recordings during periods of highest vibration. Utilizing the DDS sensor in the BHA over multiple runs, engineers were able to pinpoint specific intervals of destructive vibration. These studies allowed the rig team to identify causes and ultimately focus corrective modifications upon equipment and drilling practices. Frequency analysis was instrumental in helping to isolate the destructive excitation mode of vibration as bit generated WHIRL. Detailed information helped bit vendors modify bits, which resulted in the virtual elimination of WHIRL. MWD components were upgraded; improved drilling practices were identified and adopted by the operator.

In conclusion: since the vibration analysis has been compiled and changes made, MWD failures have gone from averaging more than one failure per well to zero failures in over twenty-seven completed wells. This sudden decrease in trouble time has dramatically enhanced the efficiency of Coil Tubing Drilling Operations. Vibration analysis is continuing within the Coil Tubing Drilling Program for Prudhoe Bay using new generation vibration sensors incorporated within the MWD Tools.
Socio-Occupational Health, Safety and Environment in the Oil Fields of North-East India-A Challenge of 21st Century
Authors: Haldar Surajit , Nainwal S. P. , Bhatnagar S. B. L.
Published: December 2007

The basic scientific support for the oil industry comes from earth sciences. The earth sciences are, in true sense, open air sciences. All the geological, geophysical, drilling and production parties work in the open with nature and people. It is one industry which comes in contact with the people of the whole area. The co-operation and contribution of the regional people have an impact on oil exploration and exploitation. Thus, the time has come that the health and safety should be evaluated from the socio-occupational point of view.

The operational activities of oil industries in north-east India cover more than one lakh square kilometer of sedimentary tracks on the western flanks of the Assam-Arakan basin. But despite of having large geological reserves, the concentration of exploration activities are in limited areas due to the prevailing insurgency in most of these states. The frequent bombarding of oil pipelines, theft of well materials like X-mass trees, control manifold valves, pipe lines laid down for different wells, live electrical cables are the major threats to safety practices and caused number of accidents. Kidnappings, threats, manhandling, killing of employees have developed fear psychosis, a phenomenal occupational health hazard in this region. On the other hand, population explosion and subsequent encroachment of houses and villages into the drill site boundary have posed threats to social health and safety.

The central theme of this informative paper is to argue as to how socio-economical backwardness have an impact on industrial health and safety and how ‘green’ business strategies can improve the performance of socio-occupational health and safety management. An attempt has also been made to highlight the various efforts made by various oil companies to gear themselves to carry out unhindered and safe activities, save environment and still gain productivity through different measures taken in this region.
Vented Gas from Wellsite Control Equipment
Authors: Simpson David , Jensen James
Published: December 2007

Common well site control equipment is often designed to continuously vent small amounts of hydrocarbon gas to the atmosphere. While small for individual locations, the collective amount of gas can add up to many tonnes of greenhouse gas emissions each year. Converting emitting equipment to no/low bleed can significantly decrease greenhouse gas emissions with the added benefit of capturing for sales this normally vented gas. This paper addresses methods for determining the magnitude of the emissions, identifying the issues that must be considered when retrofitting a site, and a case study of the application of these techniques at over 4,000 well sites.
Needed: More Coordination Between Earth Scientists and Petroleum Engineers
Authors: Halbouty Michel T.
Published: December 2007

Halbouty, Michel T., Member SPE-AIME

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

The author is severely critical of management for the flagrant waste of "brain-power" in the manner in which geologists, geophysicists and petroleum engineers are segregated in their endeavors. He stresses that the three disciplines must be fully coordinated, today and in the future, if we are to attain a respectable self-sufficiency in energy in this country. The petroleum engineer should become a member of the earth science exploration team and, conversely, the earth scientist should become knowledgeable with engineering principles which could be applied in principles which could be applied in earth science studies. It is the responsibility of management to encourage this relationship. The various innovations of study which the geologist, geophysicist and the petroleum engineer should follow in the exploration, development and production of new oil and gas reserves are production of new oil and gas reserves are described in detail. Much of the continuing education programs of the three disciplines should be combined so that the representative of each discipline will have the opportunity to exchange ideas pertinent to overlapping interests.

Introduction

I will concentrate my remarks on three disciplines - - geology, geophysics-and petroleum engineering. Throughout my presentation I will, occasionally, combine geologists and geophysicists and use the term earth scientists. Also, from time to time, I will refer to earth scientists as explorationists.

The efforts involving geology, geophysics and petroleum engineering must be fully coordinated, today and in the future, if we are to attain a respectable self-sufficiency in energy in this country.

In order to understand what is needed between these three disciplines it is important for us to go back to the first of January, 1901, and review the status of world production.

The world's annual production was about 138 million barrels. Russia was the leading oil-producing nation with an annual output of 68 million barrels.
Safety Leadership in the Offshore Oil and Gas Industry
Authors: O'Dea A , Flin R. H.
Published: December 2007

This study is about identifying the leadership styles and behaviours of offshore installation managers (OIMs) that are predictive of workforce safety behaviours. Two parallel stepwise multiple regression analyses were employed to identify the variables that are useful in predicting two safety outcomes: workforce safety initiative and workforce carefulness. Results of the two analyses produced dissimilar results indicating that different factors influence different aspects of workforce safety behaviour.
Use of Quantitative Biomarker Analysis in the Differentiation and Characterization of Spilled Oil
Authors: Stout Scott A. , Naples William P. , Uhler Allen D. , McCarthy Kevin J. , Roberts Lyle G. , Uhler Richard M.
Published: December 2007

The defensible identification of spilled crude oils and petroleum products and their correlation to suspected sources is a critical part of many oil spill assessments. Quantitative ‘fingerprinting’ analysis, when evaluated using straightforward statistical and numerical analyses, can provide simple yet defensible means to differentiate among qualitatively similar oils and provide the best assessment of a source(s) for spilled oils. Biomarker concentration data are a particularly useful quantitative measure that can benefit most oil spill investigations. Biomarkers’ specificity, diversity, complexity, and relative resistance to weathering make them extremely useful ‘markers’ in the characterization and differentiation of spilled oils, any candidate source oils, and background contamination.

In this paper the methodology and precision of data developed by quantitative gas chromatography-mass spectrometry operated in the selected ion monitoring mode (GCMS-SIM) is demonstrated. These data are evaluated using a statistical and numerical process that results in the defensible identification the source(s) of a spilled oil (heavy fuel oil) from among over 50 candidate sources.
CRM Training for UK Offshore Safety Inspectors
Authors: Miles Robert W. , O'Connor Paul
Published: December 2007

This paper describes a small pilot project to apply a form of human factors training called Crew Resource Management (CRM), which is widely used in aviation, to the training of HSE (OSD) Inspectors. The training is delivered over two days and consists of six core topics (situation awareness, decision making, communication, team working, fatigue, and stress). The course was evaluated by obtaining feedback from the 21 Inspectors who participated in the training regarding the course content, assessing any change in attitudes pre and post-training, and by evaluating participants’ responses to accident scenarios pre and post-training. The response from the participants was generally positive. However, it was noted that the course required to be further tailored to the particular job carried out by OSD Inspectors.