bluuebunny/crossref_metadata_2025 huggingface dataset:
Invariant Imbedding Identification of a Dynamic Rock Fracture/Drilling Model
Authors: Eronini Iheanyi E.
Published: December 2007

The Invariant Imbedding Technique was used to simultaneously identify rock and rock-bit parameters and estimate the state in a dynamic rock fracture model applied to the bit tooth drop test. The results indicate possible Improvements to the rock description and suggest that this model may be adequate for drilling data analysis. Also application of the method to rotary drilling and bottom-hole measurement systems is possible but it is limited by the required data rates.
Occurrence and Distribution of Overpressures in the Northern North Sea Area
Authors: Lindberg Per , Riise Raoul , Fertl Walter H.
Published: December 2007

Detection and evaluation of abnormal formation pressures is critical to exploration, drilling, and production operations.

Occurrence and distribution of abnormally high-formation pressures encountered in the exploration for hydrocarbon resources has been studied on a regional basis in the Northern North Sea. Detailed data on subsurface pressure environments encountered in wells drilled in Norwegian and U.K. waters are presented for the Viking Graben, East Shetland Basin and the Bergen High.
Global, A New Approach to Computer-Processed Log Interpretation
Authors: Mayer C. , Sibbit A.
Published: December 2007

A new computer-processed log interpretation chain, GLOBAL, uses a structure independent of model and logging suite. An error model is defined relating tool measurements to petrophysical parameters such as porosity, lithology, and fluid saturation. Then, using a minimization routine, GLOBAL searches for the solution with the minimum error. This solution is considered the most probable answer.

A quality curve is presented indicating how well the answers fit the chosen model. The curve helps to determine if the model is inadequate, or if insufficient information is available to solve the interpretation problem.

The main advantages shown by the examples analyzed are: Simultaneous use is made of all combination of logs, including experimental or recently introduced sensors.The approach works for very complex litholo-gies.It is adaptable to all kinds of models and local conditions.
Oil Field Operational Control Systems
Authors: Hodge Bartow , Hodgson Robert N.
Published: December 2007

Publication Rights Reserved

This paper is to be presented at the 39th Annual Fall Meeting of the Society of Petroleum Engineers on Oct. 11–14, 1964, in Houston, Tex., and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and considered for publication in one of the two SPE magazines with the paper.

This automation system provides for automatic custody transfer, well testing, surveillance, and supervisory control for leases and individual wells.

Each well is automatically switched to gauge in a programmed sequence and for a programed time duration; to determine the net oil, water, and gas production of each well; to transmit this data via wire line or microwave to a central office where it is processed and stored in the computer's memory; and to provide weekly and monthly production reports.

Automatically clean, measure, and ship crude production from cleaning plant to pipeline departments; furnish cleaning plant oil inventory and chemical usage in treating, daily and on demand.

Automatically check all critical points of operation at guage and tank settings and advise location and nature of any malfunction, monitor each well's flow and transmit alarms to central office for determining well producing days as well as malfunction information. This includes local control, remote control, and computer control.

— Data shall be automatically accumulated in the field, transmitted to the central point, and processed as required for operations and accounting needs.

—Overriding the above considerations are:

Reliability Expandability Ease of Maintenance Training of operating and maintenance personnel.

Introduction

Oil Field Management - The New Way.

Single integrated systems that monitors and controls oil field operations at widely separated points on a round-the-clock basis and, at the same time, provides advanced data processing services to both management and engineering personnel, are now becoming reality with present day computers and instrumentation equipment.

Computers, such as the IBM System/360 now offers in a single system the compatible, expandable, monitoring, processing, control, and communication abilities needed.
Solar Powered Injection Controller Utilizing Bottom Hole Pressure Sensing Device
Authors: Treadway Robert B. , Roye J. E. , Westerman G. Wayne
Published: December 2007

An innovative new water injection controller has been developed which will significantly improve water injection into wells, especially those exhibiting no measurable surface pressure. The new system consists of a motor control valve, turbine meter, injection controller, and bottom hole pressure (BHP) device, with power supplied by a solar panel, negating the need and added expense of running power to each well. The new system has the capability to monitor well BHP, compare the BHP against a preset value, and adjust the injection rate accordingly. The system will eventually have the capability to run step-rate tests and pressure fall-off tests automatically, as well as perform temperature surveys. Since the unit is installed in the tubing in much the same manner as a wire line tool, no pulling unit expense is incurred.
Modelling Reservoir Geometry with Non-Rectangular Coordinate Grids
Authors: Wadsley W. A.
Published: December 2007

This paper describes a practical method for using non-rectangular grids in reservoir simulation. Such grids can easily be constructed for two- or three-dimensional studies: for example, when the boundary of the reservoir is irregular; or, when the reservoir layers have varying thickness across the reservoir; or, to approximate principal fluid-flow directions such as in pattern displacements. Although use of such grids has been described before, the need for analytic calculation of coordinate functions, or the calculation of coordinate derivatives, has previously precluded the routine use of these methods.

In the present case a novel construction for non-rectangular grid systems is presented. This consists of approximating an orthogonal curvilinear coordinate system by straight line segments. The curvilinear system is not analytically derived but is drawn by the engineer to conform to irregular geometry and porosity and permeability trends. A new method for calculating inter-block transmissibilities and block pore-volumes is given. Other topics covered include changing grid systems during simulation, use of a radial grid in the vicinity of every well in a reservoir and convergence of a curvilinear grid in 1/8th of a five-spot pattern. Use of the method is illustrated by a heavy-oil steam-flood in a dipping symmetry element of a seven-spot pattern.
The Dielectric and Conductivity Response of Sedimentary Rocks
Authors: Sen Pabitra N.
Published: December 2007

We calculate the complex dielectric constant of brine saturated sedimentary rocks using several different models. A calculation using a self-consistent scheme gives Archie’s law in the d.c. limit. The cementation exponent, m, is shown to depend on grain shape, in agreement with experiments. The theory also agrees well with dielectric constant and conductivity measured at 1.1 GHz on fused glass heads. It is shown that by including special geometrical features, such as high aspect ratio particles, the experimentally observed salinity and frequency dependence and the extremely high values of dielectric constant at low frequencies can be explained. Rigorous bounds on the dielectric and conductivity values of a rock composite also show that large values of dielectric are possible. The polarization of the ions at the rock-water interface equally give rise to high values of dielectric constant.
A Practical Short-Term Interference Testing Method to Determine Reservoir Heterogeneities
Authors: Bandyopadhyay Pratip
Published: December 2007

Interference testing is widely used in the petroleum industry to obtain reservoir descriptions vital to the evaluation of proposed tertiary recovery projects. A new analytical method that provides an accurate reservoir description and requires only early time data was developed for this purpose. This method worked very well when applied to data from the literature and was successfully applied in the design, monitoring and analysis of interference tests conducted in a mid-continent field.

The conventional method of interference test analysis involves the application of a complex exponential integral function fit of the data to "type curves" either by least squares on a computer or by transparent overlays. In the new technique, the early interference data from each well are fit with a straight line. The slope of the straight line is then used to compare the degree of interwell communication. A practicing engineer with a pocket calculator can successfully use this method to design, monitor and analyze interference tests.

The method is particularly useful in reservoirs of wide spacing where the interference testing period can be inordinately long even when a highly sensitive pressure gauge is used. With judicious application of this technique, the test duration can be minimized considerably thereby reducing testing costs and delayed production.

The method is rigorously developed and a field example is given.
Air Injection Into a Mature Waterflooded Light Oil Reservoir. Laboratory and Simulation Results for Barrancas Field, Argentina
Authors: Pascual M. , Crosta D. , Lacentre P. , Coombe D.
Published: December 2007

This paper describes preparations for an air injection pilot into a mature waterflooded light oil reservoir in Barrancas field, Argentina. Primary development started in 1954, with waterflooding beginning in 1967. As the reservoir characteristics are quite similar to economically viable air injection projects in the Williston Basin, the feasibility of air injection for Barrancas was investigated. The upper layer has contributed 40 % of the total field production with 46 % of the injected water entering into the sequence. The three lower zones appear to be good candidates for air injection due to their current high oil saturation.

Laboratory studies carried out at the University of Calgary were aimed at determining pilot design information (self-ignition, fuel availability, air requirements). These included accelerated rate calorimetry, ramped test oxidation, and high pressure/high temperature combustion tube tests. The combustion tube showed excellent burning characteristics (temperature profiles >300 °C). A reasonable simulation match was obtained using compositional PVT from Barrancas to define the component description. The laboratory simulations were then used to explore various additional sensitivities.

The history match model consisted of a target pilot zone of six inner producers surrounded by additional outer producers and numerous water injectors. The four sequences were separated with transmissibility barriers of varying strength, and also contained channels with permeability enhancements. The magnitudes of these factors and the water-oil relative permeability characteristics were adjusted during the history match.

The black oil reservoir description was then converted to the thermal/compositional representation for the air injection sensitivity runs. Several air injection scenarios with two air injectors were considered, including variation in air injection rates and injection completion zones, and wet combustion as a follow-up to dry.

According to the results of this study, the process is technically feasible. Currently the economic aspects are being studied before pilot implementation.
History Matching Reservoir Models Simulated from the Pluri-Gaussian Method
Authors: Thomas P. , Le Ravale-Dupin M. , Roggero F.
Published: December 2007

Gaussian-related random realizations are widely used in petroleum engineering to describe permeability or porosity distributions in underground reservoirs. Except by luck, flow simulations run for these realizations do not yield numerical answers reproducing the measured dynamic data such as well pressures, flow rates, water cuts… Realizations must be modified to become consistent with the field data, which is done through an optimization process. The gradual deformation method (GDM) is a geostatistical parameterization technique introduced to change continuously Gaussian-related realizations from a few parameters while preserving the two-order statistics. In this paper, we focus on realizations simulated from the pluri-Gaussian method and we show how to apply the GDM to modify such realizations.

The pluri-Gaussian method, which is an extension of the truncated Gaussian method, is used for generating facies realizations. It shows the same general features as the truncated Gaussian method, but with a wider range of possibilities especially in terms of complexity for the generated realizations, making it possible to better represent reservoir heterogeneity. The simplest scheme followed by the pluri-Gaussian method, which is presented here, involves the transformation of two starting Gaussian realizations. The GDM can be exploited to modify both realizations independently or simultaneously. Additionally, this modification may be global or local. In other words, the GDM can be used to change the whole pluri-Gaussian realization by globally changing either one or both of the starting Gaussian realizations. It can be used also to change given subdomains of the pluri-Gaussian realization by locally changing either one or both of the starting Gaussian realizations. This capability provides a substantial flexibility to the matching process. The suggested methodology is validated on synthetic test cases, which stress the efficiency of the suggested methodology in terms of model simulation and history matching.
Fast Estimation of Performance Parameters in Fractured Reservoirs Using Percolation Theory
Authors: Masihi M. , King P. R. , Nurafza P. R.
Published: December 2007

Fractured reservoirs have heterogeneities on all length scales which affect all aspects of flow and make the reliable prediction of reservoir performance extremely difficult. The conventional approach to this is to build a number of possible reservoir models (with associated probabilities) then upscale them and run flow simulations. The problem with this approach is that it is computationally very expensive.

An alternative approach derived from percolation theory to make a very rapid estimation of reservoir performance and its uncertainty using sandbodies as flow unit was introduced by King et.al1-2. This approach is based on the permeability contrasts that control the flow and assumes that the permeability disorder can be approximated by either permeable or impermeable rock. The advantage is that by using some semi-analytical universal curves from percolation theory the effect of the complex geometry which influences the performance parameters can be easily estimated in a fraction of second on a spread sheet.

This study extends the application of this approach to fractured reservoirs where we can assume that matrix is almost impermeable and fracture is highly permeable. The problem with this extension is that classic percolation can not be used due to spatial correlation of fractures. However for correlated systems, the basic methodology with some modifications, which in turn depend on the nature of correlation, can be applied. We develop a stochastic methodology based on the derived spatial correlation by Heffer et.al3 to generate fracture network realizations. Then by using this spatially correlated model we use the same basic algorithm of percolation theory in 2 and 3D. Simulation results show the applicability of this approach to fractured reservoirs. Moreover we show how to include the effect of anisotropy in the universal curves in order to assess uncertainty in anisotropic reservoirs.
A Basin-Scale Shared Earth Model for Prospecting to Drilling and Beyond
Authors: Vittachi A. , Jones S. , McKenna K.
Published: December 2007

Recent developments in software are beginning to deliver the use of a single "toolkit" to store, visualize and synthesize geological, geophysical and engineering data – allowing, for the first time, the creation of "true" multidisciplinary Shared Earth Models (SEM).

There have been several hurdles to creating these models in the past: First, scale difference – pore scale for a petrophysicist, well scale for the driller, reservoir scale for the RE, and prospect or regional scale for the geoscientist have hindered tighter integration. Second, the wider E&P communities have viewed integration only in terms of their own team foci – partly due to the difficulty of amalgamating domain specific data – the geophysicist's preferred domain being time, a driller's being depth, and a reservoir engineer's being temporal and spatial data. Third, we have limited integration to a subset of the E&P community with, for example, economic models not being an integral component of SEM. As a result, mistakes have commonly been made at interfaces between disciplines as one group hands off its output to another.

Using a 3D modeling software platform, a SEM of the Columbus Basin in offshore Trinidad was constructed. Scalability is a key component of the SEM – with support for individual prospects or regional scale. The relational framework facilitates an environment that can rapidly make computations across scales, allowing, for example, a casing design to be generated taking a reservoir scale model and translating it to the well scale. With the advent of 4D data handling, basin evolution, migration of fluids, pressure and other time variant properties are integrated into the SEM. This flexibility allows fluid migration studies to be better linked with prospecting.

Creating a unified and scalable model promoted wider ownership and engagement – going beyond the geoscience and reservoir disciplines to engage the drilling, facility, economic and strategy communities. The SEM environment facilitated better cross-functional inferences to be made – with economic models being directly linked to the earth description and associated uncertainties.
New One-Trip Completion Technology for Sand Control Applications
Authors: Garfield G.
Published: December 2007

This paper will discuss a new technology that installs perforated casing and sand control in a single trip. The system incorporates telescoping perforations containing sand control media into ordinary API casing, run into the hole on standard liner hanger equipment. Applications for this technology include both producers and injectors, particularly those needing zonal isolation.

The key aspects of this technology, particularly the sand control media, sealing wax/polymer, and flow-actuated landing collar, will be discussed in great detail. Critical laboratory testing will also be reviewed, as well as installation procedures and cost analysis.

Application

The information presented in this paper is applicable to production and injection wells in sand producing formations.

Results, observations and conclusions

A new completion technology has been developed that eliminates the need for perforating and for pumping sand control media. A one-trip sand control completion method that has zonal isolation capability has been developed.

Significance of subject matter

New one-trip sand control completion technology offers a large potential for significant capital expenditure savings.
The Conceptual Design of a Non-Invasive Solids Free Drill-in Fluid
Authors: Martins A. L. , Waldmann A. T. A. , Ribeiro D. C. , Massarani G.
Published: December 2007

Designing drill in fluids which can guarantee minimum invasion into the reservoir rock is a must for open hole completion wells. The industry has proposed several ideas to deal with the problem, most of them based on adding bridging agents to the fluid formulation. Such agents would block pores near the well bore and, consequently, prevent additional fluid to invade the rock, but often require acid treatment for their removal.

A different concept is proposed for controlling invasion in this article: designing a polymer based fluid which would generate extremely high friction losses when flowing through a porous media without generating extra losses while flowing in the well. In this case the fluid would present proper flow and solids transport properties in the well and would not invade the rock formation.

Experimental results obtained with the flow of different polymer solutions through consolidated inert porous media show that the viscoelastic behavior of fluids can be a major restriction to fluid invasion. Based on a viscoelastic resistive force proposition for the porous media, flow characterizarion maps defining viscous flow, elastic flow and viscoelastic flow regions are obtained

This article deals with the optimization of the drilling fluid viscoelastic parameters, such as the first normal stress difference and the extensional viscosity, aimining the minimization of fluid invasion through oil reservoirs. The arrival of this rheology controlled invasion concept brings to the polymer manufacturers a new challenge: the development of a highly viscoelastic polymer with non damaging behavior and adequate wellbore properties.
M-6 Steam Drive Project. Preliminary Results of a Large Scale Field Test
Authors: Van Der Knapp Willem
Published: December 2007

RESUME

The M-6 steam drive is being carried out in a fully depleted, heavy oil reservoir of the Tia Juana field, Bolivar Coast, Venezuela. The test comprises 151 wells of which 19 are injectors forming a semi-open hexagonal injection pattern.

Prior to full scale injection at the start of 1978, three pilot hexagons were advanced, one in November 1975 and two in July and August 1976. Performance data of these hexagons and of the whole project over a period of 4 and 3-1/2 years, respectively, indicate that there is a remarkable uniformity in the behaviour of this steam drive if compared to a small scale test in the northern part of the giant oil field carried out in 1961 at a distance of 12 km of the M-6 project.

The present test, though on a commercial scale, is still considered of an exploratory nature and meant to advance the existing knowledge in thermal recovery. For that reason a large amount of data have been assembled on steam generation and distribution, fuel consumption, petrophysical and geological studies, tracer tests etc. In evaluating the performance use is made of empirical, analytical and numerical models. Partial studies, carried out in the context of the project, merit special contributions to conferences like the SPE one. The purpose of this paper is to review the activities two interdisciplinary project teams are carrying out.
A New Technique for Obtaining Pressure Buildup Data in Oilwells
Authors: Kabir C. Shahjahan , Hasan Abu R.
Published: December 2007

A mathematical model has been developed on the principle of mass balance of the gas component for an oilwell (pumping or flowing) which enables one to calculate the annular gas volume, including gas bubbles in the oil column. The knowledge of annular gas volume at a given instant of time can then be used to find the pseudo length of both oil and gas columns and hence the bottomhole pressures. This technique can be used to obtain pressure buildup data. In addition the flowing bottomhole pressure prior to the shut-in can be determined in the same manner to allow calculation of productivity index (PI) and to evaluate pumping well performance.

The proposed method has distinct advantage over the conventional acoustic well sounder (AWS) technique which measures the actual gas-liquid interface in the annulus. Experience has proven that the AWS technique becomes inconsistent and difficult to interpret, particularly when the oil has foaming tendencies. The AWS method requires knowledge of the gas-cut oil column gradient (estimated by an empirical correlation) when the flowing bottomhole pressure is below the saturation pressure. The advantages of the new method over the use of bottomhole recorders in a pumping oilwell is the cost saving (pump and rods need not be pulled), flexibility of data gathering and the obtaining early tine data (e.g. pws @ Δt = 0 for type curve analysis).

A field test has been conducted using high resolution pressure transducers to demonstrate the applicability and accuracy of the proposed method for a flowing oilwell.
Three-Dimensional Simulations of Uranium Leaching and Aquifer Renovation
Authors: Kossack Charles Ayres
Published: December 2007

A multi-component, three-dimensional model was developed to simulate the fluid flow phenomena occurring during the in situ uranium leaching process and subsequent aquifer renovation. This fluid flow model uses knowledge of the total dissolved solids (TDS) history of the pregnant solution. The model history matches TDS trends of the plant and in doing so calculates the TDS concentration buildup in the pattern and ion excursions into the formation. Specialized subroutines are described which account for the operation of a surface plant (its effect on reinjected leachant solution) and transverse dispersion of ions.

The advantages of studying the fluid flow with a three-dimensional reservoir simulator is demonstrated by two case studies. The first application shows the effect on leaching and aquifer renovation when the completion intervals of the injectors and producers do not match. The second application-describes the effect transverse dispersion has on the buildup of TDS in a low permeability layer adjacent to a high permeability layer. A novel process is suggested to rapidly cleanup this contaminated low permeability layer during aquifer
New Mexico’s First Uranium in Situ Solution Extraction Project
Authors: Coleman K. A. , Stewart G. W.
Published: December 2007

The New Mexico Environmental Improvement Division (NMEID) licensed New Mexico’s first in situ uranium solution extraction project, a pilot test, on December 26, 1978· The license was issued based on environmental data submitted by Mobil Oil Corporation, supple-mental information requested by NMEID, and independent calculations by NMEID.The pilot test is located in the southwestern quadrant of Section 9, Township 17 North, Range 13 West, McKinley County, New Mexico, within the Mobil Crownpoint project area.

The Crownpoint project area is distinct from existing commercial scale in situ projects in that the ore bodies are nearly 2,000 feet deep, three to four times the depth of ore bodies in Texas, and the permeability is lower. An extensive pilot test program of three years was planned for Mobil to determine the technical feasibility, environmental impact and economics of in situ solution extraction in the Crownpoint area prior to expansion into commercial production.

Mobil is maximizing environmental protection by the utilization of precautionary controls. To minimize any irreversible insult to the groundwater only a small portion of the aquifer is leached at any one time. Monitor wells are used for early detection of any potential horizontal and vertical leachate excursion. In the event of an excursion, production in the affected area would be increased relative to injection until the water quality is restored. Waste by-products will be stored in plastic lined ponds until the solids are permanently disposed at a licensed facility. Baseline data obtained during Mobil’s preoperational mon-itoring program will provide a comparison with the data from the operational monitoring program to aid in the development of restoration criteria. As leaching operations in one part of the ore body are completed the leach zone will be flushed with water purified.by reverse osmosis or electrodialysis as appropriate to facilitate on-going staged reclamation.

Preliminary data indicates the overall effective-ness of environmental controls employed in the operation. As New Mexico’s first uranium in situ solution extraction project, this information will provide the basis for the licensing and regulation of future in situ solution extraction development within the State.
The Relationship Between Ion Exchange Resin Properties and Uranium Recovery in Fluidized Bed Columns
Authors: Boyce Thomas D.
Published: December 2007

The use of ion exchange resins for the concentration and recovery of uranium from low grade solutions is a recognized process which has been practiced for many years. The method of application has generally been downflow through fixed beds. Such a system resembles a water filter and consequently any suspended matter in the feed will be filtered out resulting in high pressure drops, channeling, inefficient operation, etc.

Many uranium ores produce very fine particles or slimes which are difficult and costly to separate from the leach liquor. Attention has been given to methods that would minimize or eliminate the need for solution clarification and thus obviate the considerable capital and operating expense involved in clarification.

The most recent method developed for recovery of uranium from unclarified solutions is the use of fluidized bed contactors. In a fluidized bed contactor, the feed solution is passed upflow expanding the resin into a fluidized state. The moving and fluidized particles create a "choke" effect upon the rising liquid and a steady state turbulence is achieved.
Thermal Alterations of Asphaltenes in Peace River Tars
Authors: Waxman M. H. , Deeds C. T. , Closmann P. J.
Published: December 2007

In 1973-74 Shell Canada Limited and Shell Explorer Limited conducted a steam injectivity and productivity test in the Peace River Bullhead sand.1 The test comprised several phases. Cold production was started on September 12, 1973. Steam injection into the same well commenced on November 29, 1973 and ended on February 6, 1974. After a 54-day soak period, backflow began on April 1, 1974 and ended on October 1, 1974. A total of 122,000 barrels of steam were injected at rates as high as 2366 B/D at less than fracturing pressure. After 175 days of back-flowing, approximately 29,900 barrels of tar were produced at an oil/steam ratio of 0.23. Temperatures as high as 311°C (591°F) were observed in the formation. On the basis of results from this test, an expanded pilot has been proposed for Peace River.2,3

In support of the above effort, laboratory work was undertaken in order to obtain mobility data for Peace River tar in its parent core material at temperatures and stress conditions simulating reservoir zones downstream of a steam condensation front. Because of possible effects on flow properties, the asphaltene and maltene components of produced tars were examined. Both the quantity and degree of thermal alteration of the asphaltenes were considered, in order to assess the influence of these factors on observed flow behavior. Based on information learned in these studies, a series of flow experiments was undertaken and will be reported in our following paper.4

Mineral-free tar was obtained from Peace River core material by means of separation procedures which minimized compositional changes of the native tar. Experimental extraction procedures and resulting tar properties for Batches 1, 2, and 5 are described in Reference 4. The maximum temperature to which these extracted tars were exposed was 70°C (158°F).
Peace River Tar Flow Experiments Under in Situ Conditions
Authors: Waxman M. H. , Closmann P. J. , Deeds C. T.
Published: December 2007

In a preceding paper1 we described some chemical properties of Peace River tars, i.e., solvation properties of asphaltenes and their reflection of the thermal history of the tar in the reservoir. It was suggested that the thermal alteration observed in tar samples produced during the Shell 1973-74 field test at Peace River could lead to important changes in the flow properties of the tar relative to its initial unaltered state.

With the above factors in mind, we have performed a series of flow experiments with Peace River cores preserved as nearly as possible in their natural state. The conditions chosen were such as to simulate the hot zone present in the Bullhead Sand reservoir during the 1973-74 field test.

All flow runs were made at temperatures of 380 – 389°F (193-198°C). The sand plugs were subjected to an isostatic effective stress of~ 1,100 psig (7,584 kPa), with the overburden pressure held at~ 1,500 psig (10,342 kPa) and the back pressure on the fluids at ~ 400 psig (2,758 kPa). This was intended to simulate original in-situ burial conditions.
The Search for Oil and Gas in Mexico
Authors: Baptista Cesar O.
Published: December 2007

I would like to thank the organizing committee of this simposium, in particular to Mr. Phil Schultz, for inviting me to participate in this event, thus giving me the opportunity and the privilege to address such a prominent audience.

I am sure that the subjects discussed here will be of special importance, mainly for those that, like myself, work in the oil industry. May the best success crown the endeavor of all and each one of you.

Throughout a large portion of the world, the evolution of society during the last one hundred and fifty years has been truly impressive. The dramatic improvement of the standard of living that has favored large human conglomerates has been of such an extent, that it has no precedent within the history of humankind.
Internal Audit of Oil and Gas Reserves
Authors: May Alan , O'Neill Donald B.
Published: December 2007

There is general consensus in the oil and gas industry that estimating reserves, both quantities and the associated values, is an imprecise science. Nevertheless, in the past two or three years, the reserve estimate has become a very important component of public reporting in the industry; and those that disclose or rely on reserve information (officers, directors, underwriters, lenders) have a responsibility to determine the estimates have been appropriately determined. This change in emphasis is not only due to the Securities and Exchange Commission rules regarding audited reserve information (now postponed) but is also caused by changing economics in the petroleum industry with crude prices and finding costs both rising rapidly. Thus, it is incumbent upon all oil and gas companies to place a higher priority on internal controls over, and internal audit coverage of, the reserve estimation process.

This document, INTERNAL AUDIT OF OIL AND GAS RESERVES should assist companies in their review of controls over the reserve estimation process and suggests an approach that internal auditors may wish to consider when auditing the functioning of such controls.

The approach described in this document involves a review of existing information rather than a full redetermination of reserves. By following the procedures outlined, the internal auditor can assess whether the work was based on proper assumptions, accurately documented and carefully performed by qualified persons under the direction of unbiased supervisors. The cost of this approach is much lower (usually no more than 10%) compared to a complete redetermination by an outside party.

The suggested audit plan requires first that an understanding be gained of the environment in which reserves are estimated. This includes the company's organization, qualifications of estimators, review procedures and other standardized approaches for reporting exceptions and monitoring of property operations. Second this understanding is confirmed through discussions with appropriate personnel, review of internal reports and, where necessary, field locations visits. Finally, based on this understanding and the confirmation thereof, the internal auditor selects a number of properties to be reviewed in detail. The sample should be representative (chiefly large but some small properties) and should comprise a majority of the Company's reserves but only a relatively small percentage of the properties. By following the detailed procedures outlined in the approach, the auditor should, if no exceptions in his test procedures are noted, be persuaded that the reserve information has been reasonably determined.
Work Commitment Bidding as a Method of Subsidizing Development of Federally Owned Energy Resources
Authors: Said Mark C.
Published: December 2007

Work commitment bidding is available for mineral leasing on the Outer Continental Shelf, and has been considered for leasing the National Petroleum Reserve in Alaska. This leasing system isan imprecise method of subsidizing domestic energy development. While certain non-market benefits arguably exist to warrant a subsidy on domestic production or a tariff on imports, work commitment bidding does not appear preferable to methods which raise the price received by domestic producers. Significant administrative problems also complicate any proposed use of work commitment bidding. Use of a fixed minimum work commitment offers a theoretically possible way of counteracting risk-averse behavior in high-cost exploration areas. But for such a system to work, the government must be able to adequately predict the exploration behavior of a risk-neutral firm on the tract. Areas of further study are suggested.
The Impact of Taxes on Exploration Economics in USA
Authors: Neal Randall L. , Reed Margaret E.
Published: December 2007

This paper discusses the impact of taxes at the state and federal level on typical on-shore oil and gas exploration economics in the USA. Taxes considered are the windfall profits excise tax, state production (or severance) taxes, state income tax, and federal income tax. Also considered will be market prices for oil and gas in the USA. The effect of government take as a percent of revenue, on rate of return, discounted payout, and discounted cumulative cash flow is shown on the attached tables.

The conclusion drawn is that tax laws, while rarely the most important factor to be considered when drilling a well, can have significant impact on the profitability of oil and gas ventures, and should be considered when determining where to drill. Hypothetical exploration wells were analyzed for the impact of tax laws on project profitability. The results of this study show that when factors other than taxes are postulated to be the same (such as producing rate, capital, operating costs, and prices), cash flow can vary by as much as 68% due to the differences in the tax laws. Other significant findings for the cases studied include: (a) that discounted payout varied by as much as 1.8 years, (b) that rate of return differed by up to 67% and (c) the total tax rate as a percentage of revenue had a maximum variance of 33%.
Drilling Cost Escalation in the Gulf of Mexico
Authors: Friesen George W.
Published: December 2007

This paper presents the historical trend and defines the causes of drilling cost escalation in the Gulf of Mexico during the 1970's.

The three major components of escalation are: 1) inflation, 2) supply-demand imbalance (demand pull) and 3) decreases in drilling efficiency. The decade was divided into three periods. During each period one component of escalation was responsible for most of the rise in costs. From 1970 through 1973 only inflation pushed costs upward. During 1974 and 1975 a supply-demand imbalance caused most of the escalation. Since 1975, decreases in drilling efficiency have produced the major component of escalation. During any one year or period of years, the sum of the three components will give the total escalation rate. The reasons why different components contribute more toward escalation during certain years than others are shown by following the timing of oil and gas price increases, the overall quality of the acreage offered each year in offshore lease sales and the resulting drilling activity.
Effects of Petroleum Tax Design Upon Exploration and Development
Authors: Stauffer Thomas R. , Gault John
Published: December 2007

The principle that conventional schemes for taxing petroleum or mineral resources are "inefficient" is illustrated using simulation calculations tested against an "ideal" system.

Inefficiency is defined as the relative success in maximizing expected government revenues from the resources. Most systems fail because: 1) they leave oil in limbo, i.e. unproduced because of excessive fiscal burden; or 2) they unnecessarily increase the variance in the explorationist's rate of return by undertaxing large fields and overtaxing smaller but infra-marginal fields. This increases his discount rate and reduces taxable surplus.

An "ideal" tax system is specified which maximizes government revenues while minimizing risk to the operator. Two criteria are developed: 1) the tax falls to zero on fields which yield only the minimum necessary rate of return ("marginal" fields); and 2) the after-tax present value of all fields is the same for all fields above a threshhold size.

In particular, marginal fields, while contributing little to expected values, do contribute to reducing variance and hence risk praemia by distributing the exploration costs over a higher probability of successful outcomes.
Well Log Evaluation Study of Middle East Oil Fields
Authors: Youash Younathan Y. , Halyburton Rodney V. , Mukhopodhyay Amitabha , Biswas Partha B.
Published: December 2007

In a well log evaluation of a field study, normalization of porosity logs is often necessary to get reliable results. The effect of heavy minerals should be accounted for in calculating porosity from density logs realistically. Porosity variation is mainly dependent on shaliness. The bulk volume water concept is useful in delineating zones of irreducible saturation and transition zones. For a particular rock group, water saturation is related to the resistivity by a simple hyperbolic function. The TDT log may be used in monitoring water movement and water fingering. Analog plots of results of quantitative log interpretation are useful in stratigraphic subdivision and correlation.
Optimized Drilling in Remote Areas
Authors: Deerhake William F. , Khalaf Fouad , Seehafer John A.
Published: December 2007

Corporate Computer Centers and timesharing networks have provided the drilling industry with access to a variety of applications software associated with the optimization of drilling operations. But, even with today's worldwide communications networks there are still areas where remote access to such technology is not possible.

The purpose of this paper is to show the experience of the Gulf of Suez Petroleum Company (GUPCO), a joint venture company between Amoco International Oil Company and Egyptian General Petroleum Company, in utilizing mini-computers to optimize its remote drilling operations and assist in the storage and retrieval of drilling data.
Use of Complex Weak Acid in Canyon sand Stimulation
Authors: Armendariz Victor M. , Barringer David K.
Published: December 2007

One of the primary concerns in completion practices for the Canyon Sand in Sterling, Schleicher, Sutton and Crockett Counties has been to balance possible formation damage with completion costs. The low productivity, and until very recently, the low gas prices for this area has made the use of "exotic" fracturing treatments very difficult to justify. The fluids were normally a gelled water or gelled weak acid system, often used with CO2. In those instances where the treatments are performed via tubing, low injection rates often contributed to screenouts. The recent advent of cross linked water based fluids and more effective clay stabilizers has reduced both the screenout problems and formation damage. Within the last 8-12 months, a complexed weak acid system has been developed which has demonstrated a combination of most of the advantages of the other systems with very few disadvantages.

The ability to transport sand out to the drainage boundary is the ideal stimulation practice for almost any "tight" sand.1 This idealized treatment, though, is often not economically justifiable due to the inefficient nature of the fracture fluid, especially the earlier fluids used in this area. In this paper, we will investigate the theoretical and practical aspects of pumping a complexed weak acid system. This system possesses a large number of the desired characteristics for use in the Canyon Sand -- high viscosity, low friction loss, low pH compatibility with CO2, compatibility with clay stabilizers and fluorocarbon surfactants, low fluid loss, and excellent sand transport properties.
New Completion System Eliminates Remedial Squeeze Cementing for Zone Isolation
Authors: Oliver James E.
Published: December 2007

A new completion system has been developed which provides permanent and positive zone isolation and eliminates the need for remedial squeeze cementing. This system utilizes one or more long external casing packers that are positioned across the completion interval and inflated with cement during the primary cementing operation. Packer inflation exerts a hydraulic centralizing force on the packer mandrel to center it in the borehole and surrounds it with uncontaminated cement. As the packing element expands, it conforms to borehole irregularities. After the cement sets and the casing is drilled out, the packer(s) is(are) perforated and the zone(s) completed using normal completion practices with assurance that vertical fluid migration, via the casing-wellbore annulus, into or out of the perforated interval, is prevented.
Generalized Welge Construction for Two-Phase Flow in Porous Media in System with Limited Miscibility
Authors: Helfferich F. G.
Published: December 2007

The Welge construction to establish saturation profiles or histories in one-dimensional displacement of two completely immiscible phases in porous media is generalized for systems with limited miscibility of the two phases. The extension is applicable to any number of components, all of which may partition between the two phases. Instead of a diagram of fractional flow versus saturation of either phase in the conventional Welge construction, the extension uses a diagram of overall fractional flow versus overall volume fraction of an arbitrary component. The principle of construction remains the same. However, the different nature of the curve, in particular the discontinuities in slope, give rise to a more complex behavior. The various types of behavior which can occur in systems with S-shaped fractional flow curves within the two-phase region are discussed.