bluuebunny/crossref_metadata_2025 huggingface dataset:
Professional Responsibility And The Employed Engineer*
Authors: Harwell Thomas A.
Published: December 2007

Introduction

This paper will consider some of the legal problems arising out of the professional responsibility the employed petroleum engineer. Those problems peculiar to the independent engineer, who holds himself out as problems peculiar to the independent engineer, who holds himself out as a consultant or works under contract will not be directly considered, although some reference will have to be made to the independent engineers position since the basic principles which regulate the performance of an position since the basic principles which regulate the performance of an engineers duties are generally the same whether he is acting as an employee or independently. There appears to have been little effort in the past to hold petroleum engineers legally responsible for their activities. There are almost no reported cases involving the liability of an engineer or particularly defining the nature of his responsibility, although the dearth of reported cases does not necessarily mean the profession has been totally free of such problems. The writer is personally familiar with at least three Instances where serious claims were made against engineers by persons who relied upon their reserve estimates. On the whole, petroleum engineers appear to have been exposed to much less in the way of direct claims than have of other professions. At the same time, the relative infrequency of claims should not be taken as an indication that the situation will not change and there are, in fact, good reasons for believing one must expect more frequent attempts will be made to charge engineers and the companies who employ them with responsibility for losses suffered or thought to have been suffered as a result of their actions.
Professional Liability Insurance
Authors: Waddell James P.
Published: December 2007

Introduction

As a layman to the petroleum engineering field I do not profess to have a complete understanding of the hazards inherent in your work. Likewise, as a layman to the legal profession, I will not attempt to predict trends in the area of Professional Liability litigation. As an insurance Professional Liability litigation. As an insurance broker, however, I can discuss what is RISK, as it is related to Professional Liability; why you, as engineers, can be held accountable for loss sustained by others; and how you can protect yourself and your personal assets through various forms of indemnification and insurance.

DUTY = RISK

The case law in the United States which defines professional liability is rooted in English common law. an properly understand the origins of this legal concept, it must be well understood that the theory of Negligence is the basis of such liability and has been an accepted legal theory since the Eighteenth Century.

A first-year law student learns in his second semester, thanks to his Torts II professor, that a cause of action for Negligence is professor, that a cause of action for Negligence is based on the following elements:A duty, which is an obligation recognized by the law;A failure to conform to a required standard, commonly known as a breach of duty;A reasonably close causal connection between the conduct of the one who owes the duty and the resulting injury; andActual loss or damage resulting to the interests of another.

The early English Negligence cases which are the basis of Professional Liability have as defendants people who held themselves out to the public as having special skills in particular fields. The plaintiffs, or injured parties, particular fields. The plaintiffs, or injured parties, in these cases usually were people having direct dealings with the defendants and suffered an alleged damage (usually monetary) because of the negligent act, error or omission of the defendant arising out of their dealings. In every case there existed a direct relationship between the plaintiff and the defendant, a contractural relationship, privity. It is this privity that was the basis for establishing the element of duty in a Negligence cause of action.

The American case law on Professional Liability continued this concept of privity up into the Twentieth Century. What this meant was that a professional was immune from suit unless there existed some sort of contractural relationship between the complaining party and himself; and therefore damages were limited to the value of the contract plus limited extra expense. With out this privity a duty could not be established. In other words, an injured third party had no cause of action in Negligence; only those party to the agreement could bring suit.

Unfortunately, this is not the legal climate today. Privity is no longer necessary to establish the element of duty in a successful suit couched in the language of Negligence.

In 1922 an important case was decided by the Court of Appeals in New York and the opinion written for that Court by Justice Cardozo.
Heat Seeking Laser Sheds Light on Tern
Authors: Woodrow C. K. , Drummond E.
Published: December 2007

This paper describes the deployment of an optical fibre distributed temperature system, in a well on the Tern Alpha platform, which provides a measure of temperature in the wellbore. The temperature is measured using pulsed laser optical time domain reflectometry technology. As with virtually all such ventures into the unknown utilising new technology, several surprising results have been encountered, spawning local interest in accelerating the use of this potentially useful reservoir management tool.

This paper also describes what distributed temperature profiling using optical time domain reflectometry is, what it's for, and why it adds value. The paper highlights the early data acquired from the recent deployment activities on a well drilled from the Tern Alpha platform located in the Northern North Sea.

The vision is to be able to measure the ‘health’ of the well using it's temperature as an indicator, rather than waiting for a problem to develop and have to ‘diagnose’ using ‘post mortem’ production logging activities.
Slim Hole Saga
Authors: Dupuis Dominique
Published: December 2007

In the early 90' s, mid 90' s, one route to minimise drilling costs was to drill Slim Hole wells.

Were assessed the geological data acquisition means in diameter ranging from 4 ¾" to 3 ⅜". Also was assessed the production limits with wells having over all 4 ¾". Those hypothesis were validated.

Drilling contractors and operators worked together, designed and built dedicated equipment, drilling rigs fit for purpose.

The industrial drilling programs took place, economic results were encouraging, it demonstrated global drilling cost decrease ranging from 30% to 50%.

After few years, Slim Hole drilling has been forgotten.

The paper will outline what has been achieved and will analyse the reasons of the complete lack of interest: economical, technical, psychological barriers.
Visualization: Game Changer, Facilitator or Gimmick?
Authors: Wright W. , Holt J. , Rezmer-Cooper I. , Minton R. , Ramshorn C.
Published: December 2007

Visualization: What value does it bring today, and what can it potentially bring to well construction?

Many in the industry today regard it as a gimmick that looks nice and may be good in the Geoscience domain but has no real place in the well construction arena. However, that perspective is rapidly changing.

In varying environments outside the petroleum industry three-dimensional visualization has demonstrated many diverse benefits. This paper discusses the gains realised so far and future potentially rich areas to exploit, in the framework of well construction. Visualization allows complicated geometric and computational models to be simply represented; wells can more easily be linked to the larger picture of the field. No longer is there a need to use terms that confuse all but the individual discipline experts, a picture is now available. This speeds and facilitates the communication and mutual understanding of problems and potential solutions. Discipline experts can look for creative solutions to be suggested from their extra-discipline peers, small and subtle changes are much more easily dealt with, and the exercise becomes a shared-learning experience. Teams start to appreciate what is involved in the collaborators disciplines, thereby facilitating future work in the team. Visualization enables a common language to be established for future communication amongst a multi disciplinary team. Mutual understanding and appreciation of problems can greatly enhance team performance.

Once a model of a field is created, that includes offset well data from the drilling of the wells, we have, an intuitive repository of knowledge for future well construction projects that can be used by rig-site engineers for real-time decision-making, directional drillers for assessing anti-collision risks, and a simple and effective tool for current or future peer reviews to interrogate and more easily understand historical information in the form of knowledge.

Perhaps the most powerful benefit of all for the technique is the draw that it provides to bring people together.
New Mud Pulse Telemetry Techniques for Deepwater Applications and Improved Real-Time Data Capabilities
Authors: Hutin R. , Tennent R. W. , Kashikar S. V.
Published: December 2007

Increasing water depth, total well depth, synthetic mud systems and increasing measurement complexity pose unique challenges for real-time data transmission via mud pulse telemetry. In deepwater environments, where the use of synthetic oil-based mud is prevalent, low water temperature significantly increases mud viscosity which reduces the signal strength at surface and makes detection of the signal more difficult. Noise within the mud channel further hinders transmission of downhole data. With rig rates approaching $350k per day and total well depths beginning to exceed 10700 m (35,000 ft), operators cannot afford to drill ahead without good quality real-time downhole data. On recent wells in deep water conditions in the Gulf of Mexico as many as seven different measurement while drilling/logging while drilling (MWD/LWD) tools have been run concurrently. Some of these tools may include the capability to produce real-time images. There is thus an increasing demand for higher data rates coupled with more reliable telemetry to transmit all this data to the surface in real-time. Recent advances in MWD tool design, signal strength prediction, and signal recovery on the surface, using advanced digital signal processing techniques, have made it possible to double telemetry data rates while also reducing error rates in the data received at the surface.
A New Method of Preventing Wear in Drilling and Combination Risers
Authors: Haberer Joseph F.
Published: December 2007

Multiple incidents of riser wear resulting in the loss of riser integrity have occurred worldwide in recent years. The increasing failure rate and the move to deeper water depths and longer riser systems has sparked an interest in the deepwater community to discover means of reducing wear in the riser or eventually eliminating wear completely. In response to this problem, new internally applied, welded and thermal spray coatings have been developed and tested. These new materials, when applied to the internal bore of the riser, dramatically reduced the amount of wear the riser sample experienced during the wear test in relation to uncoated riser coupons. The article outlines the goals of the tests, test parameters, and relates the findings, wear-reducing capabilities, and operational feasibility of the materials tested.
Planning and Execution of Big Bore Wells - Offshore NW Australia
Authors: Dolan S. P. , Williams G. J. , Crabtree R. J.
Published: December 2007

Two wells were spudded in August 1999, on the Woodside North Rankin A (NRA) gas / condensate production platform with the intention of completing them as Big Bore producers. These wells were drilled into the Perseus reservoir, which can be accessed from the NRA platform at a horizontal step out of approximately 3500m. The NRA platform is located 135km offshore from the North-Western coast of Australia.

The Big Bore well design incorporates 9.5/8" production tubing to maximise production and subsequently halve the Unit Technical Cost (UTC) of Well Construction per unit of gas production ($/MMscf/d). Larger tubing is used as production from the highly permeable reservoirs is tubing constrained with the current 7.5/8" tubing. The additional cost of a Big Bore well is 10% when compared to the cost of a comparable conventional well.

This paper will describe the Well Construction related Front-End Engineering, Detailed Planning and Execution phases. The paper does not describe work done by other disciplines such as Production Technology and Process Engineering.

In particular, detailed engineering such as casing wear, integrity issues, major tasks hazard management, extensive communication requirements and equipment issues will be highlighted.

Results and lessons learnt from the planning and execution phase are analysed with a view to future improvements in the continued development of the Big Bore well designs.
Coiled Tubing Drilling: Continued Performance Improvement in Alaska
Authors: McCarty Thomas M. , Stanley Mark J. , Gantt Lamar L.
Published: December 2007

Coiled tubing drilling (CTD) has thrived in recent years on the North Slope of Alaska. To date, CTD has sidetracked over 250 wells, in a continuous program of activity since 1995. In that time Alaska has become a proving ground for coiled tubing drilling tools and techniques. CTD has matured into a highly efficient and economical means of sidetracking wells on the North Slope. Key reasons for the success of the program include: continuous utilization allowing rapid learning; a culture of technical innovation; effective performance-based service contracts; the right people with the right expertise; and the vision & support of senior management. This paper will summarize the performance improvements realized in North Slope CTD operations, detailing how the tools and techniques have changed.

Applying new technologies and improving existing tools are major levers of CTD progress. Major performance improvement areas include, window milling, BHA reliability and dealing with lost circulation. Reliability improvements in equipment and persistent innovation will continue to fuel coil tubing drilling's underlying economic performance in Alaska.

Included in the paper is a discussion of the remaining problems associated with through-tubing, slim-hole drilling using CTD technology. Examples of what new CTD technologies are being used, or are about to be implemented in Alaska, will also be presented.
Operational Efficiency on Eight-Well Sidetrack Program Saves $7.3 Million Vs Historical Offsets in MP 299/144 GOM
Authors: Williams Chad , Mason John S. , Spaar John
Published: December 2007

This paper will describe how the operator planned and drilled an eight-well sidetrack program, including one horizontal application, in Main Pass 299/144 field, Gulf of Mexico (GOM), in record time. This achievement was accomplished by improving operational efficiency (incident free) and reaching bottom hole objectives quickly, thus reducing open-hole exposure and costly "flat" time. The authors will discuss changes in the BHA, including mud motors, AKO settings, steerable ream while drilling tools and roller cone bits in addition to synthetic mud systems, that allowed each sidetrack operation to successfully drill oversize (eccentric technology) hole and hit the directional targets in record time.

The authors will discuss why different technologies were chosen and outline successful operations. A case study will be where a 7–5/8" steerable ream while drilling system with a 4–3/4" steel tooth pilot bit was able to build from 0° to 90° in one run, a record for the area.

Finally, the authors will document, with historical offset data, how improving operational efficiency and new bit technology reduced costs by approximately US$7.3 million on the eight-well program. Analysis will include a mechanical risk index that takes into account a variety of well variables to objectively compare costs on wells drilled in GOM.
Simulation of Super-K Behavior in Ghawar by a Multi-Million Cell Parallel Simulator
Authors: Dogru Ali H. , Dreiman William T. , Hemanthkumar Kesavalu , Fung Larry S.
Published: December 2007

This paper describes an application of a Massively Parallel Reservoir Simulator for a Giant Carbonate Reservoir with faults, fracture and Super-K zones. It is shown that by using a multi million cell description, premature water breakthrough and complex reservoir behavior is captured with minimum up scaling of the original geological description. The new technology used in this work provides significant reduction in simulation model construction and history matching time.

Super-K is a well-known phenomenon in parts of Ghawar where it provides extremely large conductivity to fluid flow. These formations are comprised of vugs, faults, fractures and stratiform dolomite rocks. They form effective flow conduits for water and impact the overall sweep. For the proper accounting of complex heterogeneities, a portion of the reservoir was simulated using a 2.5 million-cell reservoir simulation model. The fault map from the 3-D seismic was incorporated; a thin layer described stratiform Super-K layers with 70 Darcy permeability. A dual porosity type grid was imposed to handle the high permeability conduits. The fine grid in the area of interest was gradually coarsened for the proper accounting of boundary fluxes.

This model with over 50 years of history and about 800 wells, was run using Saudi Aramco’s parallel simulator, POWERS1. The total execution time was 4 hours. Premature water breakthrough in the middle of the reservoir was matched closely. The phenomenon of water movement in the vertical direction was duplicated as observed in the field. This study has shown that the ability to handle extreme heterogeneities leads to a more realistic history match. State of the Art technologies enable engineers to build, execute and complete the history match in a few months.
Improved Oil Recovery by New Horizontalization Strategy in Giant Carbonate Reservoir
Authors: Salameh Lutfi A.
Published: December 2007

This paper presents the merits and demerits of the multilateral horizontal applications in a giant Middle Eastern carbonate reservoir. It also discusses the main achievement of a new optimized development strategy to improve oil production, control waterfronts, and maximizing the optimum oil recovery.

Difficulties encountered from the current multilateral horizontalization (MLH) policy are also discussed, including the impact on oil production, water evolution, sweep efficiency, cost and the optimum oil recovery.

Results obtained from the detailed full field simulation study will be addressed for proper assessment of the performance of the current development plan and other recommended alternative optimum schemes for short and long terms of the field development.

The simulation study concludes that the use of horizontal wells single or multi lateral holes is critical and directly impacts the oil production. Areal and vertical balance / imbalance vertical sweep efficiencies are also effected by alleviating water movement and enhancing well productivity or injectivity.

A new optimized horizontalaization strategy was recommended based on the results of this study. The new policy has been implemented successfully in 16 producers during 1999. Initial assessment of the performance of these wells indicates an exceptional success in terms of increasing oil production and deferring water breakthrough as a result of improving vertical sweep efficiency.
Comprehensive Solutions for Transient-Flow Problems in 3D Homogeneous Domains
Authors: Rahman N. M. Anisur , Bentsen Ramon G.
Published: December 2007

In the petroleum engineering literature, analytical solutions have always been treated as benchmarks for many complicated situations in reservoirs. But efforts to develop analytical solutions for some transient-flow problems have been hindered seriously due to a lack of appropriate mathematical tools. However, this study demonstrates that the use of an integral-transform technique (ITT) results in the comprehensive development of analytical solutions for transient-flow problems subject to three-dimensional (3D) flow in a cylindrical coordinate system. This approach presents the solutions in the time and space domains. Variable production rates and all possible combinations of the boundary conditions are also considered in the formulation. Time-dependent rates and boundary conditions are dealt with directly, avoiding the use of the principle of superposition or Duhamel’s theorem.
Lessons learned from Wireline Formation Testing with Single and Multiple Probes
Authors: Su H. J. , Al-Anezi K. G. , Sinha S. P. , Ceyhan A. G.
Published: December 2007

Previously there were few RFT data available for the Wara formation of the Greater Burgan field. Therefore, during recent drilling, pressure measurements were made to investigate if vertical pressure equilibrium exists in the formation after a production history of more than fifty years. The erratic nature of measured pressure profiles indicates that vertical communication is poor in the reservoir.

In each of the pressure measurements, a single probe was inserted into the mud filtrate zone, and then about 20 cc of liquid was collected. In addition to obtaining the pressure value, we also derived the permeability value by diagnosing the pressure derivative signatures. Multiple probes were also used to evaluate vertical permeability over an interval of 2.3 feet. This paper describes how we analyze the data and overcome the problems encountered. We demonstrate that 3D-reservoir simulation of the formation test can improve the quality of data interpretation. A summary of the analytical method development is also given.

Due to the high precision, 0.01 psi, of the quartz gauge, the single-probe pressure derivative data quality was satisfactory for low permeability sands and the analytical method could derive both the horizontal and vertical permeability values successfully. However, for high permeability sands, there often existed a pressure hump immediately after shut-in and it resulted in unrecognizable signatures.

A non-linear regression method was used to interpret multiple-probe test data. However, sometimes a simultaneous pressure match for all the probes was difficult to achieve by the analytical model. 3D finite-difference simulation was required to fit the data and characterize the geological heterogeneity. Single-probe pre-test results were used to provide a good initial permeability guess for the numerical model. Gamma ray and formation image loggings were proven valuable to determine the layering of the numerical model. Finally, core measurement and buildip test results were compared with formation test results.
Novel Compact Oil/Water Separator Tested in Nimr
Authors: Nnabuihe Larry
Published: December 2007

A novel compact oil-water separation concept using 2 hydrocyclones in series with recycle has been proven through laboratory testing and Nimr wellhead trials.

The objective was to investigate the technical feasibility of using hydrocyclones at the wellhead to separate Nimr crudes prior to considering a downhole trial. With ‘light’ Nimr crude, good water separation efficiency was achieved with a residual OIW better than conventional separation. With more typical heavy viscous crude, similar separation efficiency was attained but OIW levels were significantly higher.

The technology provides a viable option for separation at the wellhead, for example prior to reinjection in water flood projects or where surface infrastructure is flow constrained. Reservoir benefits through improved pressure support or sweep could make the business case for downhole separation more favourable; however, it poses challenges to downhole monitoring and well architecture.
Investigation of Revaporization of Retrograde Condensate
Authors: Li Shi , Zheng Xitan , Dai Zhijian , Luo Kai , Chen Gang , Liu Ning
Published: December 2007

A series of experiments have been carried out in order to quantitatively investigate the revaporization efficiency of retrograde condensate by dry gas injection. The experiment includes three main parts: (1) gas injection below the dew point pressure in the PVT cell, (2) gas injection above and (3) below the dew point pressure in a long-core flooding apparatus. Instead of the simple synthetic fluid and the packed core systems usually used in the previous literature, an actual gas condensate fluid and an approximately one meter long-core were employed here. The tests with long-core apparatus show that more condensate above the dew point is recovered than below the dewpoint, forcefully justifying the traditional argument that the full pressure maintenance is superior to the partial pressure maintenance according to the condensate recovery. An interesting discovery is that dry gas can effectively revaporize not only the intermediate but also the heavy hydrocarbons (i.e., C20+), which is in contrary with the common belief that the heavy hydrocarbon cannot be revaporized by dry gas.
A New and Rigorous Equation for Modeling Gas Condensate Well Deliverability Including an Experimental Study of Revaporization of Retrograde Condensate
Authors: Xie Xingli , Luo Kai , Song Wenjie , Li Baozhu , Li Shi , Zheng Xitan
Published: December 2007

As the well flowing bottomhole pressure falls below the dew point, liquid dropout occurs in gas condensate reservoirs. Gas condensate well behavior is unique in a sense that it is characterized by severe loss of well deliverability. Thus well productivity and gas re-injection are two among the critical issues in development of many gas condensate reservoirs, particularly for the high condensate yield cases.

Generally retrograde condensate is viewed immobile at reservoir conditions so that the standard dry gas flow equations based on flow-after-flow, isochronal and modified isochronal testing, etc., have frequently been used to analyze gas condensate well productivity. However, due to the combined effects of the bi-phase flow of gas and condensate near the wellbore and reduction in well deliverability caused by liquid buildup, this approach seems to be inadequate and usually leads to misleading results, suffering doubt and criticism up till now. Therefore, there is a need to develop a rigorous equation to express the thorough flow behavior of gas and condensate in porous media.

Based on a detailed description of flow behavior in gas condensate pools, a definite solution problem is formulated. Subsequently the analytic solution is derived under pseudo-steady-state conditions. The derivation procedures are detailed. Finally a rigorous overall deliverability equation desired is obtained by incorporating the effect of non-darcy flow in the vicinity of well bore. Then the parametric calculation methods are discussed briefly. A calculation example using the new equation is compared with the result calculated by the standard dry gas productivity equation. The comparison shows that the standard binomial productivity equation usually used in the dry gas condition over-predicts the production potential of gas condensate well.

Additionally, in order to investigate the quantitative efficiency of condensate revaporized by lean gas injection, the laboratory experiments of gas injection have been made in a PVT cell, and above and below the dew point in a long core apparatus. Comparison of the tests shows more recovery of condensate in longcore above the dewpoint is obtained than below the dewpoint, justifying the popular argument with regard to the condensate recovery that the full pressure maintenance is superior to the partial pressure maintenance. However, the full pressure maintenance in the high-pressure reservoirs may not be the best choice due to the expensive investments on equipment. A comprehensive cost evaluation is suggested, but this is out of the scope of the present study.
Estimation of Evaporated Oil for a Sixty Two Year Old Immiscible Gas Injection Project
Authors: Al-Mahroos Faisal M. , Kumar K.
Published: December 2007

This paper presents a novel approach to estimate the recovery of oil by the stripping of the lighter components by the injection gas, using the fluid characterization models derived with semi-continuous thermodynamics method in earlier studies.

Bahrain Field is an asymmetrical anticline trending in the North - South direction. The sedimentary column extends from Cambrian Saq sandstone to the Miocene reefal deposits exposed on the surface. The field contains twenty-two reservoirs with the hydrocarbon content varying from tarry oil in Aruma to dry gas in Khuff reservoirs. The geology of the field is extremely complex with a large number of faults occurring in the Wasia group formations, which contain the major oil reservoir of Bahrain field, the Mauddud reservoir. The field was discovered in 1932 and gas injection in the under saturated Mauddud reservoir was initiated in 1938. Over the years of injection a secondary gas cap has developed. The dominant recovery mechanism is gravity drainage with crestal injection of gas from the Khuff zones. The reservoir being heterogeneous and structure complex with a large number of faults, most of the injected gas gets produced.

In addition to the above recovery mechanism, stripping of the lighter components in the oil by the "dry" injection gas, is significant. In fact the associated gas produced is enriched with the stripped oil and forms the major feed stock for the LPG recovery plant. To understand the recovery mechanisms and to provide fluid characterization for the simulation work in progress, characterization of the reservoir and injection fluids were carried out in earlier studies. These fluid models were validated with the available experimental data satisfactorily. This paper describes how these fluid representations were used along with the production and the compositional data of the associated gas produced, to simulate the gas injection process. Also with the current strategy of development of the field, future oil recoveries expected from the stripping process have been estimated.
Integrated Study of a Fractured Middle East Reservoir with Stratiform Super-K Intervals – Part 2: Upscaling and Dual Media Simulation
Authors: Cosentino L. , Coury Y. , Daniel J. M. , Manceau E. , Ravenne C. , Van Lingen P. , Cole J. , Sengul M.
Published: December 2007

The paper describes the upscaling and reservoir simulation of a giant Middle East oilfield, whose geological modeling is described in a companion paper (1). The main objective of the study was the simulation of the irregular water advance observed in some parts of the field, as a consequence of peripheral water injection.

Three scales of heterogeneity were identified in the characterization phase, namely the matrix, the stratiform Super-K intervals and the fractures. To accommodate the different hydraulic properties of each heterogeneity system, a dual-media approach (dual porosity and dual permeability) was used.

The assignment of the effective properties to the simulation grids (matrix and fracture grids) was performed independently for the three heterogeneity systems. In particular, the geostatistical facies model was upscaled using algebraic methods, while the stratiform Super-K layers and fractures properties were explicitly reproduced at the simulation gridblock scale, through an original upscaling procedure.

The history match was achieved in a short time, by a small variation of the fractal dimension of the fracture distribution and without resorting to any local modification.

Simulation results showed that the fracture system was the controlling factor in terms of water advance and breakthrough, while the impact of the stratiform Super-K layers proved to be of second order.

In a later stage, the model was utilized to run production forecasts under different exploitation scenarios.

Conclusions of this study indicate that for such porous and fractured reservoirs with stratiform Super-K occurrences, a detailed characterization of all the heterogeneity systems, coupled with a dual-media formulation, are necessary requisites for accurate reservoir simulation and effective reservoir management.
Selecting Perforation Intervals and Stimulation Technique in the Khuff Reservoir for Improved and Economic Gas Recovery
Authors: Zillur Rahim , Al-Qahtani Mohammed Y.
Published: December 2007

Saudi ARAMCO has initiated an acid fracturing program to treat the carbonates of the Khuff reservoir in the Ghawar field in the eastern province of Saudi Arabia. Khuff reservoir belongs to the Permian age and is encountered at an average depth of about 11,500 ft. Two main producing intervals of this reservoir, Khuff B and Khuff C, have tested high quantity of condensate rich gas.

Khuff reservoir consists mainly of dolomite and limestone sections with streaks of shale and anhydrite that constitute the non-permeable and possible fracture barrier zones. The reservoir extends up to several hundred feet in thickness with varying quality and production potential. A careful planning of completion technique and choice of stimulation is important for efficient fracture coverage and improved hydrocarbon recovery. This paper addresses the general methodology of selecting perforation intervals and stimulation technique to develop and enhance production in the Khuff carbonate gas reservoir.
Phase Behavior of Highly Waxy Gas Condensate Systems
Authors: Luo Kai , Li Shi , Zheng Xitan , Liu Henian , Zhong Taixian , Zhu Yuxin
Published: December 2007

As still deeper formations are drilled, gas condensates containing high carbon-number hydrocarbons which may precipitate during production and in the reservoir, are encountered. An increasing focus of attention on its phase behavior has been made worldwide in recent years. The main purpose of this paper is to investigate experimentally the characteristics of phase behavior of this new type of gas condensate systems with high wax content. Therefore, a series of experiments are carefully made for different GOR fluids, including constant composition expansions and the determination of wax deposition points. The separator gas and liquid are collected from the same producer and recombined in the laboratory to cover the ranges of GOR encountered in the field.

The results show that the quality lines of the highest GOR fluid in two-phase region are parallel to each other and terminated at the appearance of wax deposition. Thus the fluid has no convergence point, or critical point. It is also found that the biphase regions expand with the increase in GOR. In other words, gas injection may highly increases the saturation pressure locus contrary to the usual belief that the two-phase region will become smaller as more gas injected into the reservoir leads to more leanness of the reservoir fluid. Another interesting finding is that the more amounts the heavy hydrocarbons, the lower dew- & bubble- point pressures of the gas condensate systems used in this study. This is also contrary to the previous literature results that increasing amounts of heavy hydrocarbons increase the retrograde dew point pressure. Thus the deduced conclusion28 that a compositional gradient in the segregated fluids results in higher observed dew point pressures at the bottom of the fluid column, may not be made to the highly waxy gas condensate systems used in this study.

Additionally we also found the wax deposition temperature increased with decreasing GOR.
The Compositional Characterization of Gas Condensate Fluids - A Review Featuring the Impact of the Analysis Data Quality on the Accuracy of Equation of State Based PVT Predictions
Authors: Broad T. J. , Varotsis N. , Pasadakis N.
Published: December 2007

The compositional analysis of gas condensate reservoir fluids is an integral part of their routine PVT laboratory analysis. Naturally occurring hydrocarbon mixtures contain thousands of components, the presence and concentration of which determine their physical properties and phase behavior during production. Accurate compositional data is the prerequisite for generating reliable Equation-of-State (EoS) based predictions of the PVT and physical properties of the reservoir fluids over a wide range of conditions as well as for quality assurance of the crude.

Unfortunately, no standard methods are available in the petroleum industry for measuring compositions. Different analytical techniques are employed for obtaining the molecular composition of tank oil such as direct injection analysis, simulated distillation by gas chromatography, separation of the sample by fractional distillation, identification of specific compounds by mass spectrometry, component group distributions by High Pressure Liquid Chromatography (HPLC), etc. In addition, several correlations are utilised for defining the physical properties of the single carbon number fractions (SCNF) and of the heavy end fraction. This diversification inevitably leads to differences in the compositions reported by various laboratories which can significantly affect the quality of the predictions provided by the EoS based simulators.

This paper reviews the current analytical techniques and discusses their advantages and disadvantages. The compositional data obtained on gas condensate reservoir fluids by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and fractional distillation are compared and assessed. The effects that the differences in the derived molecular compositions bear on the EoS based predictions of the physical properties of petroleum fluids are illustrated using test cases studied in the PVT lab. These effects are particularly pronounced for the estimation of the retrograde liquid deposit curve, which constitutes a crucial set of data for efficient reservoir management.
Adjustment of Differential Liberation Data to Separator Conditions
Authors: Al-Marhoun Muhammad A.
Published: December 2007

The actual reservoir process is neither flash nor differential. Thus, regardless of the testing procedure, some adjustment needs to be made to the resultant data to approximate the fluid behavior in the oil production process. The conventional method of adjustment extrapolates to negative values of solution gas-oil ratio and formation volume factor leads to values less than one at low pressure. Both extrapolations do not conform to the physical behavior. This is due to the fact that the conventional approach does not observe that the oil relative density at reservoir conditions is the same regardless of the process.

This paper presents a new approach to the adjustment of differential liberation data to separator conditions. This approach is based on the fact that both flash and differential data should give the same value for the oil relative density at the reservoir conditions. This is achieved by correcting all the properties, i.e. solution gas-oil ratio, formation volume factor, gas relative density and oil relative density. The new method overcomes the disadvantages and limitation of the conventional approach. This method is tested on 400 PVT files from all over the world and the result is consistent with physical behavior. A sample calculation is presented to outline the new method.
Determination of In-Situ Precipitation of Barium Sulphate During Coreflooding
Authors: McElhiney John E. , Sydansk Robert D. , Lintelmann Kurt A. , Benzel William M. , Davidson Kimberly B.
Published: December 2007

In-situ barium sulphate precipitation was observed during coreflooding experiments conducted at frontal velocities of 0.31 m/day in fired Berea sandstone cores. The precipitate was observed during a laboratory study on the transport of sulphate ions contained within the injection water that displaced a synthetic formation water containing barium ions. Two separate cores were 100% saturated with formation water similar to that of a West African offshore reservoir (240 ppm barium and 230 ppm strontium) and were respectively flooded with synthetic seawater containing 2860 ppm sulphate and synthetic low-sulphate (desulphated) seawater containing 36 ppm sulphate. Careful measurement and comparison of flood effluent profiles of precipitating and non-precipitating ionic species such as sulphate, barium, strontium, etc. indicates that barium sulphate precipitated in situ during the flooding experiments. In the case of the seawater flood, approximately 27% of the barium that was contained in the formation water resident in the core was precipitated. In the case of the low sulphate seawater flood where the propensity for barium sulphate precipitation was low, results were less dramatic and determination of the exact amount of precipitated barium sulphate was less certain, e.g., approximately 10% of the barium was precipitated. Temperature and pressure conditions for these coreflooding experiments were ambient temperature (~70°F) and atmospheric pressure. The Berea cores utilized were 5.08 cm in diameter, 15.2 cm long, and averaged 112 md permeability and 17.5% porosity.

Results of this coreflooding study indicate that in-situ precipitation of barium sulphate occurs while even low-sulphate seawater is flooded through core material that is saturated with a formation water containing barium. During reservoir-scale flooding with low sulphate seawater, a favorable consequence of the barium sulphate precipitation is that the sulphate scaling potential is substantially reduced at the producing wells. This work represents a first step in generating experimental data that can be input into a mathematical simulator for predicting the propagation rate and the breakthrough time, under reservoir conditions, of the sulphate ions of the injection water -- both for low and high sulphate content injection waters.
Coiled Tubing Seismic While Drilling
Authors: Jackson T. S. , Gorrara A. J. , Chmela W.
Published: December 2007

The efficient exploitation of hydrocarbon resources is strongly dependent on the drillers’ ability to position wells accurately. This is particularly challenging for smaller targets and on long reach or horizontal wells. Conventional wireline VSP's can provide valuable assistance but such operations require either the drill string to be removed from the hole or the pumping of the geophone tool through the drill string. Both of these methods add time to the well construction. In long sections of open hole wireline operations may present risks, in the form of sticking and potential fishing operations, which prevent VSP surveys being acquired in lookahead mode. Ideally, VSP data would be acquired at several stages of the drilling process to enable corrective action to be taken to assist accurate bit placement. The costs in terms of rig time alone generally make this option prohibitive.

Ongoing developments for cost effective exploitation of mature and pressure-depleted reservoirs have led to wider applications for coiled tubing drilling. The combination of a seismic tool with the coiled tubing drill string therefore provides an ideal configuration to reduce drilling costs and optimise well placement. This paper discusses the conventional methods available for geosteering of the bit, the additional benefits of incorporating a seismic tool into the drill string and describes the development of a seismic while drilling tool (SMWD) for coiled tubing drilling.
Chemically-Enhanced Drilling With Coiled Tubing in Carbonate Reservoirs
Authors: Rae Phil , Di Lullo Gino
Published: December 2007

There has been a dramatic increase in the use of continuous reeled tubing (coiled tubing) for drilling operations. Much of this increase can be attributed to improvements in the quality and dimensions of coiled tubing itself – pipe sizes have steadily increased over the years from 1 inch OD to 3 V inch OD and bigger. Other developments have included improved downhole motors and, for directional work, sophisticated survey and orienting tools that can be controlled, in real time, from surface.

Despite these developments, CT drilling is still applied to very few wells, or a tiny percentage of the total drilling market. There are many reasons for this including high equipment and personnel costs, low rates of penetration (ROP), and issues related to the reliability of high-cost "smart" bottom hole assemblies (BHA's) needed for directional work. The idea that CT drilling would offer a cheap alternative to conventional rigs is, and probably will remain, an unfulfilled pipe-dream. However, CT drilling certainly has its place, particularly for vertical well deepening and for slimhole multilateral work. The method presented here provides the opportunity to improve the efficiency and lower the cost of such operations.

This paper describes a technique that we call Stimulation While Drilling (SWD), a drilling method that is particularly applicable to the use of coiled tubing. In particular, the method is intended for use in the drilling of multiple short, lateral drainage holes originating in the main borehole and extending outward radially through the reservoir, at one or several depths. However, any hole, including the main borehole itself, can be created using this technique, depending on the lithology. This ability to make large multilateral conduits, at high speed, in underbalanced conditions, if desired, and with no drilling damage offers significant advantages for well construction and completion, particularly in hard carbonate reservoirs.
Pushing the Boundaries of Coiled Tubing Applications
Authors: Sumrow M. H. , Economides M. J.
Published: December 2007

This paper offers a critical review of the capabilities and limitations of coiled tubing as used in matrix stimulation. A method to determine the effective reservoir thickness that can be treated, as a function of coiled tubing size, wall thickness, yield strength, length and well depth is outlined. The method allows the user to push the boundaries of coiled tubing applications to its practical limits.
The Responsiveness of Global E&P Industry to Changes in Petroleum Prices: Evidence From 1960 – 2000
Authors: Inikori Solomon O. , Kunju Mahendra Kumar , Iledare Omowunmi O.
Published: December 2007

Perhaps no industry has witnessed a more cyclical activity than the petroleum industry! Oil and natural gas account for a substantial part, over 70 percent, of world energy demand and utilization beside the worldwide application of its by-products. It is the main source of foreign exchange earnings for many developing economies.

Crude oil price volatility, especially in the recent past, has made decision-making and strategic planning extremely difficult for oil companies. Oil companies have responded to the low oil prices by reducing research and development budget, capital spending, and employment pattern. The operators are even more cautious than ever before in capital spending and expansion despite the current rising trend in crude oil prices.

This paper uses the basic laws of demand and supply and the concept of elasticity as well as user cost relations to evaluate the responsiveness of oil industry activity to changes in oil and natural gas price from 1960 to 2000. It relies on some E&P industry performance measures to evaluate the state of the oil and gas industry in response to crude oil price variability and instability. The results show that the profit margin of the major operators have been on the decline since the advent of OPEC and so is the demand for labor in the industry. The consequences of price instability have led to mergers and acquisitions and internal re-organization in order to attempt to maximize profit in the past few years. Finally, the paper attempts to forecast future oil and gas prices and evaluate their effects on oil industry activity over the next decade using economic impact analysis and the economic concept of price elasticity.