bluuebunny/crossref_metadata_2025 huggingface dataset:
A Simple Method for Estimating Well Productivity
Authors: Brooks James E.
Published: December 2007

We present a simple method for estimating the well productivity of a natural completion. The method gives quick, accurate estimates of productivity that agree well with established finite-element calculations. We show that three nondimensional groups - determined by the major governing parameters: penetration length, shot density, perforation tunnel diameter, permeability anisotropy, wellbore damage length and perforating damage - control most of the functional dependence of well productivity. One practical application of the method is in selecting the best perforating system from a suite of alternatives. The analysis is also useful in determining economical trade-offs between marginal increases in productivity and contemplated improvements in any of the perforating parameters (perforation length, shot density and tunnel diameter).

Introduction

Researchers have been devising various methods for estimating well productivity from a perforated formation for many years. Most methods assume that the flow in the permeable formation can be modeled by potential theory, that is, as a solution to Laplace's equation, subject to particular boundary conditions. An oft-quoted study is that of Tariq, who used a finite-element method to solve numerically the well flow over a wide range of perforating and formation parameters. These results were later reduced to a series of analytical approximations by Karakas and Tariq that now serve as the basis for two commercially available computer codes that are in common use today.

Although useful in estimating well productivity and in assessing trade-offs between different gun systems, the computer analyses sometimes tend to obscure insight to the relative importance of the various competing parameters. Nondimensional analysis can often be of great use in these situations by grouping together the most important parameters to reveal the underlining functional dependencies. And that is the purpose of this study.

Basis of the Method

The method assumes that the dominant variables determining productivity are: perforation length (P), shot density (N), diameter of the perforation tunnel (d), anisotropy or ratio of horizontal permeability to vertical permeability of the formation (a), diameter of the wellbore (D), length of local wellbore damage (L), and the damage caused by the perforating jet (bc). The method assumes that there is no appreciable difference in productivity caused by the phasing of the gun, as long as the perforations are distributed along a spiral pattern. Both the wellbore damage and the perforating damage (the local impairment to permeability caused by the perforating jet) are initially assumed to be zero. Later on, we show that these effects can also be included as part of the analysis.
Experimental Study on the Impact of Perforations on Hydraulic Fracture Tortuosity
Authors: van de Ketterij R. G. , de Pater C. J.
Published: December 2007

We performed scaled model tests to study the relation between completion and treatment parameters and the near wellbore geometry for highly deviated, cased perforated wellbores.

We have instrumented our casings to observe the moment fluid flow around the casing causes a significant increase in the amount of pressure acting on the wall of the borehole. When fluid flow around the liner occurs extensively before fracture initiation, this leads effectively to an open hole situation at the moment of initiation. Otherwise the perforations will be the only possible initiation sites.

In our experiments with a perforation phasing of 90° the perforations on top of the borehole acted in most cases as initiation sites. We performed stress calculations with a simple analytical model to understand the influence of the perforation angle on initiation pressure and fracture propagation.
Coiled Tubing Horizontal Underbalanced Drilling Project; Costs and Operational Analyses
Authors: Borbely L. , Brazier R. , Giddings C. , Cox R.
Published: December 2007

Coiled tubing drilling remains one of the fastest growing technologies in the drilling industry. As of year-end 1996 approximately 60 horizontal underbalanced wells have been drilled in Western Canada with coiled tubing. The benefits of this technology are intuitive, however there have been few opportunities to make direct comparisons to adjacent horizontal wells drilled with conventional techniques.

In 1996, Crestar Energy Inc. contracted Canadian Fracmaster Ltd. to drill 5 horizontal underbalanced wells in Southeast Alberta. The drilling of these wells provided opportunity for project analysis of operational factors and costs. This paper presents the results of the five wells drilled, analyzes time breakdowns for key operational steps. Cost comparisons of these wells with similar conventional overbalanced wells and initial reservoir productivity will also be assessed.
Field Installed Coiled Tubing Gas Lift Completions
Authors: Tran T.B. , Miller J. , Woodell M.E. , Johnson H.R.
Published: December 2007

Gas lift has long been used as a petroleum industry vehicle for secondary artificial lift. Typically run in a conventional jointed tubing completion string or, more recently, in manufacturer installed spoolable systems utilizing continuous pipe; new applications utilizing modifications of existing equipment and processes have enabled "on-location" make up of coiled tubing conveyed gas lift strings and subsequent installation and/or extraction of same. This application was designed as an alternative to conventional gas lift systems as well as other means of artificial lift in order to effectively address mechanical problems due to wellbore conditions and expensive and frequent workover operations all dictated by marginal well economics from tail-end field reserves. Results from this completion method have been mechanically and economically successful for this application and field installed coiled tubing gas lift has been expanded to exploit other formation types.
Development and Use of an Analytical Model to Predict Coiled Tubing Diameter Growth
Authors: Brown Paul A. , Dickerson Jessica L.
Published: December 2007

When coiled tubing (CT) is plastically deformed by bending over a reel or guide arch, several important changes are known to occur. The tubing suffers irreversible and cumulative fatigue damage, and the diameter may increase in the presence of internal pressure. Fatigue has been the subject of extensive study, and several analytical and empirical models have been successfully developed. Diameter growth has received less attention, but recent industry trends are causing it to become more of a concern. These trends include:–Use of tubing for a greater fraction of its fatigue life–Repeated local cycling at higher pressures (e.g. drilling)–Greater use of large diameter CT–Operations at very high pressure >5000 psi)

It is worth noting that all of the above trends have been made possible in part by improved modeling, the effectiveness of which is undermined if an important parameter affecting the working life of the string is neglected, such as tubing diameter.

This paper presents an analysis of a new analytical model for predicting diameter growth, and compares the estimated working life of a tubing string when both fatigue and diameter growth are considered. Model predictions are compared with observed data from full-scale tests and fatigue test machines. Use of the model in real-time tubing monitoring software as a means to identify potential problem areas is discussed.
Update on Advance Composite Spoolable Pipe Developments
Authors: Fowler Hampton
Published: December 2007

Much of the credit for the recent rapid growth in the Coiled Tubing Industry can be attributed to the development of larger diameter and higher strength spoolable steel tubular products allowing for an expansion of the operating limits and the applications that can be performed such as drilling, completions and horizontal well servicing. The development of an advanced composite, high performance spoolable tubular product will help fuel this market expansion even further by creating additional enabling capabilities for the Coiled Tubing well servicing industry.

Conoco, Inc. initiated the development project for high-performance, composite spoolable tubular products in 1988. The initial focus was on corrosion resistant water injection lines and later evolved to a 1.5" OD composite coiled tubing. The development effort lead to a composite tube design formed by taking a thermoplastic liner and surrounding it by a carbon fiber and epoxy matrix structure. The matrix includes an external KevlarR fiber layer to provide wear and impact resistance. The advantage of a composite spoolable pipe over steel pipe is that it can be "engineered" for particular applications to take advantage of the composite's enabling attributes. These attributes include corrosion resistance, high strength to weight ratios, high working pressure capability and low material density. In fact, the current composite tubing designs weigh in at 1/3–1/4 the weight of a like OD steel tube in air and are 1/7th the weight of steel in water. This obvious advantage allows longer and larger strings of composite tubing to be handled by lower pull capacity coiled tubing units or lifted onto offshore platforms with smaller crane capacities.

This paper will review the development efforts and operational issues addressed to qualify the advanced composite spoolable tubing for several enabling applications. The first full scale field trials are scheduled to be performed in the 2nd quarter of 1997.
High Pressure Coiled Tubing Job Prepares Gulf Coast Well
Authors: Morrison Dan , Reid Kevin , Kenney Tom
Published: December 2007

This case history paper presents the details of the role played by coiled tubing in returning a high-profile, Gulf of Mexico oil/gas well to production after the well had to be shut in due to excessive sand production. The paper presents the following events/conditions:The well could not be injected into in several attempts up to 9,300 psi. Since the well had produced sand, operators suspected that a sand plug existed.The well was completed with 4 1/2", 15.1# production tubing.Coiled tubing performed offline while the rig was performing completion operations. A hydraulic workover unit would have required the rig to be moved to aid in snubbing operations.The well was 18,750 ft deep, with a wellhead pressure of 7,000 psi. The well was producing from two comingled gravel packs with a ceramic flapper installed in the upper gravel pack packer for fluid loss. The state of the flapper was unknown.A coiled tubing string of 1.25" OD and 19860 ft long was designed for the job. Wall thickness tapered from 0.156 in. at the top to 0.134 in. at the bottom to support the tensile load of the string and provide maximum cycling capabilities at the location of the ceramic flapper.

The initial goal was to use coiled tubing to wash to the bottom of the lowest gravel pack and break through the ceramic flapper with an impact tool. Due to low annular velocities inside the production tubing a special xantham based polymer/CaCl2 mixture was required to wash sand to the surface. The use of coiled tubing to wash through the production tubing in this extreme pressure/depth application allowed the well to eventually be killed by bullheading kill fluid.

The paper also presents useful information on the following coiled tubing-related issues:Tubing fatigue monitored by software that tracked tubing life and helped ensure that the tubing was not used beyond stress ratings.Coiled tubing technology has extended the working envelope for high pressure applications.
Worldwide Occurrence of Abnormal Formation Pressures, Part I
Authors: Fertl Walter H.
Published: December 2007

In the last decades, exploration for new and additional oil and gas reserves has greatly expanded laterally, both on- and off-shore, and at the same time has also greatly progressed downward to investigate the hydrocarbon potential of deep and superdeep targets. In these activities, abnormal formation pressures; i.e., pressures other than hydrostatic have been encountered on all but one continent. The present discussion attempts to compile information on the worldwide occurrence of abnormal formation pressures, which are equally important in the pressures, which are equally important in the search for and drilling and production of oil and gas.

Introduction

In the worldwide search for oil and gas, formation pressures other than hydrostatic have been encountered on all but one continent (Figure 1). Such abnormal pressures, defined by departure from hydrostatic at any given depth, may be excessively high or low, the possible modes and causes of origin being numerous.

The present discussion, unfortunately, is limited by (1) data available to the author or (2) their proprietary nature (North Sea, South China Sea, Arctic Islands). Since each country had to be treated rather briefly, selected references will assist in pursuing the subject further. All pressure pursuing the subject further. All pressure data shown in graphical rather than tabular form. Each graph includes three trend lines representing the overburden gradient of 1.0 psi/ft, which corresponds to the weight of the overlying rock series (i.e., weight of both the rock matrix and fluids) with an average density of 2.30 gm/cc, (2) the hydrostatic pressure gradient of 0.465 psi/ ft, which corresponds to the average hydrostatic gradient as found in the U.S. Gulf Coast area, and (3) the hydrostatic gradient of 0.433 psi/ft, representative of the domestic Mid-continent area.
A Method of Determining Permeability by Means of a Pulsed NMR and an Application of the Method to the Study of a Gulf Coast Supernormally Pressured Well
Authors: Seevers D. O.
Published: December 2007

A method is presented for determining porosity, specific surface area and permeability of shales by means of pulsed Nuclear Magnetic Resonance pulsed Nuclear Magnetic Resonance (NMR). The method is applied to drilling chips collected from a Gulf Coast well. Combining well data on pressure and temperature with the NM pressure and temperature with the NM determination of permeability, a calculation of vertical flux is made. An analysis of the behavior of the flux with depth suggests that clay diagenesis is responsible for the supernormal pressure. All other observed properties can be explained on this basis.

Introduction

There are many hypotheses for the cause and present day characteristics of supernormally pressured sediments. In general we do not have enough information to validate a given hypothesis. The purpose of this report is to present a method for determining the permeability to fluid flow of the shales in the supernormally pressured section. These permeabilities can be combined with permeabilities can be combined with pressure data on adjacent sands and pressure data on adjacent sands and yield the present day flux of water through the shales. A knowledge of the variation of water flux with depth will aid in understanding the cause.
A Systematic Study of Fracture Modeling and Mechanics Based on Data from the GRI/DOE M-Site Project
Authors: Wright T. B. , Green T. W.
Published: December 2007

The GRI/DOE M-Site Project involved a series of seventeen test injections pumped into three separate wet, non-economic sandstone reservoirs. Various advanced diagnostic techniques were used to characterize the resultant fracture systems. These diagnostics included microseismic-event mapping, the use of closely-located downhole tiltmeters, and numerous observations resultant from cores taken through the expected fracture azimuth. Using numerous procedures and tests, these reservoirs were more completely characterized than would be the case for a typical commercial reservoir, however the accuracy of some important parameters (specifically, some which are used as fracture simulator inputs) is still questionable due to the layered nature of the reservoirs. All seventeen of the injections were analyzed using a lumped-parameter 3D fracture simulator, both in real-time and postinjection. Using measured injection data as inputs, the simulator-predicted pressure was compared and matched to the measured data. Whenever the model-predicted fracture dimensions differed substantially from the diagnostically-determined dimensions, certain model and/or reservoir parameters were changed so that the simulator and diagnostic dimensions predictions were in agreement (with simulated and measured pressure also still in agreement). Details of the simulator analyses are presented and compared to the diagnostic interpretations. Other direct observations made from the various data are also presented.
Import LNG
Authors: Purvin Robert L.
Published: December 2007

Import LNG should represent an important addition to the gas supply of the United States but there are many political and economic factors which must be considered. It is increasingly apparent that because of rising hydrocarbon values and increasing capital costs, LNG will not be a cheap supply but it should be competitive with other substitute natural gas sources. Of particular importance is the fact that LNG can be stored and should represent the most economical source of short and intermediate seasonal and peak supply. Security of supply and foreign exchange requirements are two subjects that must be studied in major LNG importation programs but the fact that gas is our cleanest form of fuel will be a strong attraction for importing relatively large supplies if they are available at a reasonable price.

Introduction

On March 9th of this year the Federal Power Commission approved for the first time a long-term LNG import program. While this must be viewed as a landmark decision, the Distrigas project is of such a limited and specialized nature that it certainly will not set the precedent for all future LNG projects. There is no doubt that the case served to educate industry, government and the public in this new and innovative field of liquified natural gas and will therefore have served a useful purpose in setting guidelines for larger and more ambitious LNG projects. The distrigas decision culminates almost four years of activities which led to the Distrigas projects and represents a personal landmark after almost twenty years of work in the LNG field. The development of this project is in itself an interesting story but today I want to give you a broad view of import LNG, describing this new industry as a whole, pointing out its strengths and weaknesses, and even attempting to forecast its ultimate position in our future gas supply.
Casing Design for Extended Reach Wells
Authors: Jaffe Linton , Maidla Eric , Irrgang Rosemary , Janisch Werner
Published: December 2007

A method for calculating casing loads for extended reach wells is presented that helps outline field strategies to run casing in or pull casing out of the well (if necessary). It is based on defining the critical inclination for which drag exceeds the tangent weight component and considers multiple fluids (air, water, mud, heavy mud) inside the combination casing string while running it into the well to optimize hook loads (minimize or maximize depending on the desired situation).

The results show that optimization is possible but is dependent on the friction factor used for the design procedure.
Reforming Liquid Hydrocarbons
Authors: Marten Jerome H.
Published: December 2007

The paper deals with a review of the various existing processes for the production of Synthetic Pipeline Quality Gas production of Synthetic Pipeline Quality Gas from liquid hydrocarbons ranging from methanol through whole crude oil.

Commercialized processes covered include both catalytic gasification, thermal cracking and non-catalytic hydrogenation.

A brief discussion of the economics of the catalytic gasification process together with other potential applications for said process is also given. process is also given. In the United States today we are in the beginning of an overall energy shortage. While the causes and magnitude of this energy shortage are being debated at all levels of industry and government, the one fact generally accepted is that of all the energy sources, natural gas will feel the pinch first and most severely. This pinch first and most severely. This impending shortage of natural gas is the motivating force behind the renewed interest in production of gaseous fuels.

The development of processes for the commercial manufacture of fuel gas goes back at least two hundred years. One of the first processes was used in Philadelphia in 1796 to produce fuel gas for street lights. This process was based on coal gasification as were the majority of the early gasification processes. The gasification processes generally produced a product with a higher heating value of product with a higher heating value of below 500 BTU/SCF, which was referred to as "Town Gas". Originally the "Town Gas" was used for lighting and domestic heating only; but, as demand for electricity and industrial uses grew "Town Gas" production increased greatly. The development of the synthetic ammonia and methanol processes lead to the development of coal and coke gasification processes designed to produce the specific synthesis gases required.

"Town Gas" production was usually associated with the coal and steel industries. This was especially true in the United Kingdom and Europe. In the United States, an ever increasing amount of the energy requirements were supplied by petroleum products and "Town Gas" production came to a halt for all practical purposes in 1947, mainly because of practical purposes in 1947, mainly because of accelerated discoveries of natural gas reserves and development of an extensive nationwide pipeline distribution system. Europe too, after World War II, shifted to petroleum to meet the rapidly expanding energy demand. Domestic needs, however, were still supplied via "Town Gas".

In the early 1960's, with the development of the ICI high temperature naphtha-steam reforming process, which produced a 300 BTU/SCF gas, the United Kingdom's "Town Gas" industry shifted to a naphtha feed basis very rapidly. Initially LPG was used as the enriching gas; but, in the mid 1960's the British Gas Council developed a catalytic low temperature steam-naphtha gasification process, the CRG Process, which produced a high BTU gas suitable for use as the enriching gas in "Town Gas" production.
Systematic Methodology for Effective Perforation and Fracturing Strategies
Authors: Manrique J. F. , Bjornen K. , Ehlig-Economides C.
Published: December 2007

This paper discusses an improved completions methodology and criteria for perforating/fracturing based on systematic and enhanced geomechanical reservoir characterization.

Understanding of the near wellbore stress distribution is critical to implement a sound perforating strategy. Reservoir quality variations, mixed lithologies with plastic behavior and loading/unloading cycles (drilling and production operations) will alter the near wellbore stress distribution reducing the compressive stress of the rock. Thus, constant stress gradients (i.e., 0.1 psi/ft.) are misleading and rock mechanical properties measurements may prove to be of extreme importance.

The case-specific examples presented in our work, demonstrate the advantages of using a detailed geomechanical reservoir description and illustrate when the "standard" assumptions and the "one-approach-fits-all" perforating approaches are not applicable. Perforation strategies are suggested to address different and complex issues; multiple fractures, phasing, shot density, vertical coverage, natural fractures, far field stresses alignment, tortuosity and erosion effects. Reservoir performance, net pressure matches and geomechanical data indicate that effective stimulation treatments can be implemented where others have failed or unacceptable production changes occurred.

The perforating for fracturing methodology discussed in this paper places the set of perforations where they are needed the

most, accounting for stress contrasts and optimization of shot density and phasing. Easy to implement recommendations for strategic placement of perforations and the mechanics for fracture initiation from vertical, deviated and horizontal wellbores are briefly discussed.

This approach attempts to achieve effective vertical coverage and proper placement of a hydraulic fracture. As demonstrated by production results, the improved efficiency of the perforating/fracturing strategies minimizes treatment failures and has significant impact on treatment implementation and production enhancement strategies.
Application of Model Studies to the optimization of Pressures in Underground Gas Storage Reservoirs
Authors: Hardy Reginald H. , Khair Abdul W. , Kimble Edward J.
Published: December 2007

Research presently underway at the Pennsylvania State U. is concerned with the Pennsylvania State U. is concerned with the study of the mechanical stability of underground gas storage reservoirs. This research involves a number of phases including a laboratory model study which will be outlined in the present paper. paper. In these studies small scale models containing reservoir cavities of simple geometry were first loaded under typical in-situ stresses then pressurized internally until failure occurred. Microseismic techniques were utilized to detect reservoir failure.

A description of the experimental facilities and the model fabrication techniques are included along with a review of results obtained from tests on a number of differently shaped reservoir cavities. A discussion, relative to the effect of reservoir geometry and depth below surface, on the optimum storage pressure is included. In general, the results of the model study indicate that optimum storage pressures may be considerably higher than those based on the discovery pressure or the average hydrostatic gradient.

Introduction

The natural gas industry today is faced with the problem of locating and developing sufficient underground storage reservoir capacity to meet peak seasonal demands. Since it is economically desirable to store the gas at the mammon possible pressure, an accurate value for the optimum pressure, namely the maximum pressure to which a reservoir could be pressure to which a reservoir could be pressurized and still remain mechanically stable, is pressurized and still remain mechanically stable, is of great importance.

Natural gas is stored underground in former gas and oil reservoirs, aquifers and man-made cavities. As the demand for natural gas increases the necessity for storing larger and larger volumes of gas underground during periods of low demand has increased markedly. In 19701 a total of 325 storage reservoirs were reported in the U. S. The majority of underground storage was located in former gas and oil reservoirs with a lesser number in aquifers and relatively few in man-made cavities.
Enhanced Interpretation of Russian and Old Electrical Resistivity Logs Using Modeling and Inversion Methods
Authors: Frenkel M. A. , Mezzatesta A. G. , Strack K. -M.
Published: December 2007

The evaluation process for oil and gas reservoirs comprises the accurate estimation of underground formation resistivities. A substantial amount of Russian and old electrical log resistivity data has been acquired in the past that can be used in an enhanced interpretation process. Old electrical devices continue to be used in various parts of the world. Due to the characteristics of these instruments, which do not provide symmetric responses (unfocused logs), the data are difficult to interpret and require a large degree of expertise when conventional interpretation techniques are used (e.g., charttype processing). In addition, conventional interpretation does not allow for extracting all information contained in the data, for which oil and gas bearing formations may be overlooked.

Modeling and inversion methods represent an excellent way to interpret these types of resistivity logs. These methods allow for simultaneously interpreting the entire suite of available logs, incorporating the physics of the measurements, taking into account borehole, invasion, and shoulder-bed effects, and involving data uncertainties. Inversion methods provide reliable estimates of formation parameters and quality control indicators to assess the accuracy of the interpretation results.

A new philosophy for interpreting these resistivity logs, based on two-dimensional modeling and inversion, has been developed and a strategy implemented, allowing the log analyst to perform the full-spectrum of data processing required by the interpretation. The complete process involves the following major steps: data depth matching, mud resistivity estimation, log calibration, environmental corrections, utilization of prior information, and estimation of formation parameters.

The inversion technology has been implemented on both scalar and parallel machines, the latter providing a fast turn around time. The proposed scheme was evaluated on synthetic cases and applied to a set of Russian field data acquired in Western Siberia. The results are presented showing the proposed methodology's ability to obtain improved estimates of formation parameters and a consistent earth model explaining the entire suite of logs.
Tubing Joints For High Pressure Service
Authors: True Martin E. , O'Reilly W.M.
Published: December 2007

Samples of tubing joints, considered as an item of well equipment very susceptible to leakage in high-pressure gas service, were subjected to a series of tests involving thermal changes and using gas at pressures to 15,000lb/sq.in. It appears that some joints commercially available and of special design give promise of adequately containing 15,000 lb/sq.in. gas pressure under field conditions. Observations indicate that physical turns as a measurement is superior to torque as an index of make-up and relative sealing ability of a joint.

Introduction

As wells are drilled deeper, reservoirs having pressures higher than those previously encountered impose greater requirements on production tubing strings. A 14,000-ft well was drilled recently in the Gulf Coast area which encountered a formation-bearing gas at a reservoir pressure of approximately12,100 lb/sq in. After completing the well it was deemed inadvisable to produce it because well control equipment tested hydrostatically to 15,000 lb/sq in did not adequately contain pressures encountered in this gas well. An investigation was initiated to devise a method of testing equipment for high pressure gas service and to locate equipment capable of retaining 15,000 lb/sq in gas pressure. Tubing joints are particularly susceptible to leakage because of the number used and because they cannot be fully and adequately tested in their installed condition. Experience has revealed that gas at high pressures will escape through porous metals of connections which appear adequate to contain liquids at equivalent pressures. One phase of the work of this investigation has been devoted to the determination of an adequate tubing joint. The purpose of this paper is (1) to present a method for gas testing of tubing joint connections rated for high-pressure gas service, and (2) to present an interpretation of observations obtained during testing of a number of these tubing joints.

Discussion

Previous testing of pipe connections filled with liquids at high pressure included subjecting specimens to beam loading, tension, pressure shocking, and extreme thermal changes. Subjecting tubing joint samples charged with gas at high pressures to thermal changes was believed to be a more demanding test of the joint, and an installation, shown in Fig. 1, was prepared to conduct such tests with relative safety. A metal box for use as an immersion bath was jacketed with a thick layer of protective sand and fitted with observation windows of shatter proof glass and an overhead sand box.
Interactive Simulation An Answer To What Is The Question
Authors: Kaplan Michel , Wentworth Robert C. , Bryson Larry D.
Published: December 2007

Simulation is an established technique that provides a rapid and effective means of provides a rapid and effective means of evaluating existing or proposed system operations. It has proved effective in assisting managers and designers to make decisions at significant cost reductions below real-life testing. This paper explores the research and problem definition aspects of simulation. It describes a new on-line simulation technique and emphasizes the merits of an interactive approach to modeling. This approach helps the user control, from a terminal, some decisions before all data are available and all alternative decision logic has been defined.

This approach is compared to standard simulation techniques throughout each step of development study. Examples are given from pipelines, fuel supply, and power supply systems, including tankers, barges, storage tanks, and power plants.

Introduction

In practice, it is management responsibility to make things work. Good management will make its decision on the basis of performance data and anticipated problems. performance data and anticipated problems. or react to difficulties as they are encountered. Management control is not necessarily automatic, and, therefore, its logic is not always easily programmed.

Essentially, management interacts with operations, according to planned decisions, and counteracts adverse conditions as they arise. Simulation is a tool that allows the manager to anticipate operational difficulties and pretest the consequences of his decisions on existing or proposed systems at significant cost reductions below real-life testing.
Quantitative Determination of the Degree of Heterogeneity Within an Outcropping Reservoir by Magnetic Resonance Imaging
Authors: Borgia G.C. , Bortolotti V. , Dattilo P. , Fantazzini P.
Published: December 2007

Under certain conditions, petrophysical analysis of outcropping rock units may add significantly to the knowledge of a buried reservoir by providing laterally continuous control of reservoir heterogeneity. We present here the first results of a project to develop cost saving methods to improve the knowledge of reservoir heterogeneity. The study was performed on a carbonate outcropping reservoir, and the sampled rocks can be correlated with oil bearing reservoir discovered some 50 km to the W, in the Southern Apennines. The cores are highly heterogeneous, with a consistent presence of fractures and vugs; therefore standard porosity measurements are difficult to perform. Quantitative Magnetic Resonance Imaging (MRI) was used to measure porosity. About 300 MRI internal images from 46 samples, taken from 8 full-size cores, were analyzed. Quantitative determination of porosity by MRI proved to be reliable to describe the distribution of porosity at different scales, and it was successful in providing information on the lateral continuity of the porosity.

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Statistical Study of Geopressured Reservoirs in Southwest Louisiana
Authors: Perry D.R.
Published: December 2007

This study is an investigation of the higher pressure gas reservoirs, often referred to as "geopressured" gas reservoirs due to the apparent support of the earth's overburden by the reservoir fluids. The geographical area investigated for geopressured reservoirs is limited to the onshore and offshore area of Southwestern Louisiana. Within this area, most of the gas producing reservoirs are Miocene age; however, older reservoirs (to Eocene age) are also found.

The contribution of this study is to call attention to the occurrence of geopressured reserves and the favorable economics of drilling developing and producing these reserves. The unexpected distribution of the larger percentage of economical reserves at the higher pressure gradients reverses the previous concepts that geopressured reservoirs would contain small volumes of reserves. This is of particular significance to the domestic industry which must continue to drill deeper to replenish its reserve storehouse.

Introduction

The correlation of the ratio or gradient of reservoir pressure to reservoir depth expressed at the geostatic ratio and the volume of recoverable reserves from above normally-pressured gas reservoirs is the objective of this study.

The geostatic ratios studied were above normal, meaning the reservoir pressure encountered exceeded the pressure exerted by a column of sea water at the depth the reservoir was penetrated. Reservoirs that contain penetrated. Reservoirs that contain higher-than-normal pressures are considered to be supporting a portion of the earth's overburden. They are often called "geopressured reservoirs," broadly meaning "earth pressured."

Geopressured reservoirs probably were first encountered by drilling wells over thirty years ago. Early well penetrations in these reservoirs could not be controlled and the wells were abandoned. The first such occurrences would likely have occurred along the Louisiana-Texas border of the Gulf of Mexico; however, geopressured reservoirs have been discovered in several foreign countries. Data from geopressured gas reservoirs located in South-western Louisiana (Figure 1) are used in this study.

Within the past twenty years the number of geopressured gas reservoirs developed has been large enough to make a valid investigation.
Shale Minerology and Overpressure: Some Case Histories of Pressure Detection Worldwide Utilizing Consistent Shale Minerology Parameters
Authors: Gill J.A.
Published: December 2007

While sands and permeable-carbonate reservoirs once served as a convenient source of pressure measurements—and of some erroneous concepts of pressure "graients" as well—we now realize that most fluid pressures originate in the relatively-impermeable clays and shales from whence they are transmitted to the sands and carbonates, where they tend to gradually bleed off and reach "hydrostatic" equilibrium.

The water being released dynamically, continuously, and currently from the younger shales (Tertiary and into Cretaceous), during their compaction and diagenesis, appears to be primarily responsible for the generation of overpressures. This shale-pressuring follows no consistently "linear" gradient, showing many irregularities and pressure "reversals"—thereby causing, and pressure "reversals"—thereby causing, and explaining, many of oar complex drilling problems. problems. Since shales—quite thick in comparison to the relatively thin sands-are the predominant "rock" in most of our predominant "rock" in most of our sedimentary basins, their water content becomes a tremendous hydrodynamic reservoir for fluid pressures, and perhaps the origin of the pressures, and perhaps the origin of the very hydrocarbons for which we are drilling The diagenetic changes in shale mineralogy which accompany the release and subsequent movement of internal water from shales are being utilized worldwide in a convenient and reliable group of parameters for monitoring pressure changes (either up or down) from shale cuttings while drilling is in progress. When these shale mineralogy parameters are properly interted (to allow for such things as "jump shifts" in geologic age caused by folding and faulting; missing sediments; or for 11 strange" minerals squirted spasmodically by volcanic activity into the depositing shale sediments), they tend to fit the preceding generalizations and verify dynamic preceding generalizations and verify dynamic considerations of overpressuring. Four such case histories are presented here.

Introduction

Dynamic mechanisms of pressure generation are not new to this group*, having been discussed in prior symposia by Jones, Burst and several others.
Deep Wells Bit Optimization
Authors: Hameed A. , Al-Rushaid A.
Published: December 2007

Case histories from Saudi Aramco fields are cited to demonstrate how enhanced rock strength calculations from open hole logs and core data, has aided Polycrystalline Diamond Compact (PDC) bit optimization. Cost per foot reduction was a challenging target to achieve with rotary, turbine or Positive Displacement Motor (PDM) in drilling deep, high temperature hard formations.

Introduction

With the increasing number of rigs deployed to drill deep gas production and exploration wells, Saudi Aramco has utilized state of the art PDC bits available in the market to minimize drilling costs.

It is well understood that the deeper we drill, the higher the temperature and rock compressive strength. This results in higher mud weight for most cases, slower rate of penetration and thus frequent bit trips that add to the well cost.

The use of PDC bits has greatly expanded over the last decade. The reason for this is that PDC bits generally drill faster, stay longer on bottom than a roller cone bit, and perform well for a wide range of difficult drilling conditions. Moreover, they are less likely to leave junk in the hole since they have no moving parts. Typically, PDC bits drill twice as fast as roller cone bits and can often replace two or three roller cone bits in places where they are successful, Since 1989, PDC bit life has increased 115% to an average of 3629 ft by mid 1995. The 13.7% annual increase in the average operational life of a PDC bit clearly explains the growing popularity of these tools.

It is a common knowledge that PDC yields the best results in soft to medium formations. Unlike roller cone bits, PDC cutting action is by shearing the rock not crushing. Therefore, less weight on bit is required to shear the rock. This shearing action leads to a higher rate of penetrations in rocks like shales and limestone. PDC bits can be destroyed in hard formations such as granite or quartz or by nodular formations such as chert or pyrite.

The objective is to drill a well with a minimum feasible cost at the highest standards of safety and well integrity. This can be achieved by increasing the rate of penetration (ROP) and reduce the cost per foot (CPF) by using PDC bits on rotary, PDM motor and turbine.

This paper will present case histories from Saudi Aramco fields and illustrate how open hole logs, mud logs, offset bit records along with core data were utilized in analyzing the rock compressive strength and internal angle of friction to predict the drillability of the formation in order to optimize bit selection.
Collision Avoidance Using a Single Wire Magnetic Ranging Technique at Milne Point, Alaska
Authors: Mallary C.R. , Williamson H.S. , Pitzer R. , Robertson James
Published: December 2007

In high well density environments, wellbore collision avoidance typically requires creative trajectory planning, carefully executed directional drilling and rigorous downhole surveying. In exceptionally congested developments, these techniques alone may prove inadequate for accessing certain targets without violating close-approach policies. In Alaska, an adaptation of magnetic ranging technology originally developed for relief well drilling provides a safe, cost-effective alternative for drilling through such congestion. This magnetic ranging technique has been used to successfully drill to an otherwise inaccessible target.

P. 813
Geotechnical Investigations for Arctic Gas Pipelines
Authors: Bruce William
Published: December 2007

The sub-surface conditions encountered in the Arctic, critical to a natural gas pipeline design, construction and operation, require a comprehensive investigation and analysis of these conditions before confidence can exist that ground stability can be preserved. The paper outlines the preserved. The paper outlines the geotechnical investigations, analysis and design consideration performed by the Canadian Arctic Gas Study group in evaluating a gas pipeline to the Arctic.

Programs covering photo-interpretation, soils investigations, geology, mathematical modelling are explained.

The thrust of most Arcticpipeline studies is toward the delineation pipeline studies is toward the delineation and solution of problems related to permafrost. Prior to the Prudhoe Bay permafrost. Prior to the Prudhoe Bay discovery, permafrost research was viewed by many as a scientific luxury and little was known of its characteristics and behaviour. Although permafrost covers one-half of the land area permafrost covers one-half of the land area of Alaska and Canada, the engineering fraternity had demonstrated only a nominal interest into this phenomenon. The value of such information was suspect, and the hostilities of the Arctic environment was generally conceded as the major deterrent to development. our lack of knowledge of permafrost became painfully clear in 1968 and was dramatized by our urgent need for it.

The problem was magnified by the public concern and pressures for public concern and pressures for environmental preservation. No longer can the designer be satisfied with are liable and economic design, he must demonstrate that environmental disturbance is maintained with inacceptable limits. The Arctic and sub-Arctic present the supreme challenge in doing present the supreme challenge in doing so.

Most of the design and environmental concerns are related, directly or indirectly, to geotechnical problems arising from thermal changes to the permafrost, from any number of sources. permafrost, from any number of sources. Extensive knowledge has been gained in this field and analytical techniques developed to confront most foreseeable problems. problems.

The Canadian Arctic Gas Study Limited

This consortium developed from the 1972 merger and subsequent expansion of two formerly competitive groups formed to study a natural gas pipeline connection to Prudhoe Bay. By July of 1972, sponsoring companies numbered sixteen and represented production, transmission, and transportation interests.