bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressure Analysis of Gas Wells in Multilayered Reservoirs With Skin, Storage, and Non-Darcy Effects
Authors: Osman M. E. , Mohammed S. A. A.
Published: December 2007

This paper presents the first study of transient drawdown and buildup pseudopressure behaviour of a gas well located in multilayered infinite acting reservoirs wehre wellbore storage, skin and turbulence intensity effects were taken into account A mathematical model was developed to investigate the pseudopressure function and it's derivative for different situations of wellbore and reservoir characteristics. It was found that pseudopressure function ΨD, for all cases considered in this study, is characterized by a unit slope line (during early time) followed by a transition period and then a pseudoradial flow period during late time. The pseudopressure derivative function (Ψ’D*tPD) is characterized by a unit slope line, a curvature and then a constant value. The effect of the contrast in kh product on ΨD and Ψ’D*tPD was found to be significant compared to the effect of both skin factors and ϕh products. Type curves were developed for buildup and drawdown testing analysis. The drawdown type-curves can be used to analyze buildup test data as long as the duration of buildup test is less than the producing time before shuting-in the well. The fractional production rate from different layers can be evaluated using the mathematical model presented in this study. The results of a flow meter survey can be used to eva-luate the contrast in kh product of different layers.
Field Results of Applied Drilling Hydraulics in Deep Wells Using Nomographs
Authors: Mosby J.W. , Owens H.B. , Cheatham C.
Published: December 2007

One of the most important and critical factors in drilling a well is hydraulics. As wells go deeper, the drilling hydraulics calculations become more critical and lengthy. So that drilling personnel on the rigs can readily solve complicated hydraulics problems, a set of eight nomographs was developed. Mud volumes, velocities, type flows (laminar or turbulent) and pressure drops in drill pipe, across bits and in annulus are easily and rapidly found with the nomographs without solving equations. The equations derived for Bingham plastics were used in developing the pressure drop and flow nomographs. The pressure drop and flow nomographs. The nomographs have been found to be quite accurate and reliable.

Introduction

The drilling well hydraulic system is not unlike the circulatory system of the human body in its importance and functions. Good drilling hydraulics is probably the most important single factor in drilling deep, expensive wells. When drilling with water-base muds, the circulatory system of a drilling rig can be analyzed by employing the equations developed for Bingham plastics. Since solving the Bingham plastic fluid flow equations is both tedious and time consuming, nomographs were constructed. The prime reason for their development was to give the man on the rig a fast, simple, reliable means of solving his hydraulic problems. The field results have been excellent, and some of them are presented in this paper, along with the presented in this paper, along with the nomographs.

In planning development wells, parameters can usually be predicted with fair accuracy. In drilling rank wildcat wells, some parameters can be predicted, but others have to parameters can be predicted, but others have to be established while drilling. Although the nomographs presented in this paper are useful in drilling both type wells, it is in handling the unexpected problems, such as encountered while drilling wildcat wells, that they are of the most importance to the man on the rig.

BASIC REQUIREMENTS

There are many papers published in the literature which cover the different phases of planning and drilling deep or abnormally high planning and drilling deep or abnormally high pressured wells. pressured wells.
Design Of Special Cement Systems For Areas With Low Fracture Gradients
Authors: Wieland D.R. , Calvert G.D. , Spangle L.B.
Published: December 2007

Regulated fill-up cement (RFC) slurries are thixotropic systems designed to aid in cement placement and obtain adequate fill-up in areas or situations where more conventional slurries are unsuccessful. RFC slurries are thin when mixed initially, but develop a high gel strength almost immediately after placement. The purpose of the high gel strength is to make the cement column support its own weight and, thus, relieve hydrostatic pressure at the bottom of the column.

Originally developed to prevent fall-back of the cement column in areas of low fracture gradients, the RFC systems have proved capable of solving many difficult proved capable of solving many difficult cementing problems. They have application in shutting off lost circulation during drilling, patching holes in casing, and in reducing gas-cutting of the cement column during primary cementing operation.

The RFC systems compare favorably to conventional slurries insofar as chemical and physical properties are concerned and investigation of the hydraulics show they can be placed with less bottom-hole pressure than the conventional slurries. pressure than the conventional slurries

Introduction

There are areas where the formation fracture gradients are of such low magnitudes that obtaining good cement jobs is difficult. These formations are normally highly-fractured zones, shale zones, granite washes, glacial deposits, etc. When using conventional cement systems, the combination of the hydrostatic pressure and frictional pressure is of such magnitude that these zones will break down and receive most of the cement slurry. The result will be a cement fall-back, leaving long sections of the pipe with no cement to support it.

The usual approach to the fill-up problem under conditions encountered in problem under conditions encountered in such formations is a reduction of cement slurry density. This approach has several disadvantages due to the limits of cement weight variance. If a slurry is reduced to its lower limits of density, its set strength and permanence are greatly reduced. Further, with the slurry density at its lowest obtainable value, hydrostatic pressure of a column of the desired height pressure of a column of the desired height may still exceed the critical pressure of the formation. In this case, several stages of cementing will be called for. Each stage of cement has to wait until the previous stage has reached set strength previous stage has reached set strength before it can be placed.
Development of the Offshore East Wilmington Oil Field
Authors: Truex John N. , Hunter William J.
Published: December 2007

The East Wilmington Oil Field, comprising approximately 5930 productive acres, is located just off-shore Long Beach, California, and contains oil reserves of approximately 800 million barrels. It is being developed by THUMS Long Beach Company as contractor for the City of Long Beach, the Unit Operator. Development is from four, 10 acre, man-made islands and two on-shore locations. Approximately 575 wells have been drilled to date, producing from eight zones. Cumulative oil production as of June 30, 1969 was production as of June 30, 1969 was 93,485,157 barrels.

HISTORICAL BACKGROUND

The East Wilmington oil field is located in the south central part of the Los Angeles basin, on the south-easterly plunge of the Wilmington anticline (Plate 1). The Wilmington oil field overlies a basement high that extends in a southeasterly direction from Torrance oil field to Huntington Beach oil field, a distance of 21 miles. The Ranger Petroleum Co., Well No. "Watson", completed January 26, 1932, for 150 barrels per day of 14 degree gravity oil was the first commercial well completed in the field. However, recognition and development of the Wilmington structure awaited the completion of General Petroleum Corporation, Well No. "Terminal" 1, in December, 1936, for 1419 barrels per day of 20.5 degree gravity oil. Rapid development followed this event, and prior to initial drilling in the Long Beach Unit in July, 1965, approximately 3500 wells had been drilled and had produced about one billion barrels of oil from 7825 acres.

Subsidence began in the center of the field shortly after inception of production, and rapidly became a major production, and rapidly became a major problem. Pilot water injection was problem. Pilot water injection was initiated in Fault Block VB in the Upper Terminal zone in June, 1953, and was quickly extended to other zones and fault blocks. In 1956, the City of Long Beach prohibited drilling east of Pine Avenue prohibited drilling east of Pine Avenue until the subsidence was controlled, the excluded area including all the present Long Beach Unit, exclusive of Tract 2.
An Integrated Reservoir Characterization Study of a Giant Middle East Oil Field: Part 1—Geological Modelling
Authors: Shanor G. G. , Samimi Bahman , Bagherpour Hashem , Karakas Metin , Buck Stuart , Carnegie Andrew , Crossouard P. A. , Nasta Vinod
Published: December 2007

The paper presents the first part of an integrated reservoir description and stochastic geological model of the Asmari formation of a giant field in southwestern Iran. The geological model provides the geometry, continuity and connectivity of major flow units within the field, and the small scale heterogeneous lithofacies distributions within flow units. Lithological heterogeneity, extensive diagenesis, and the sparsity of well data relative to the 880 km2 mapping area necessitated a geostatistical model to provide geologically sound 3-dimensional lithofacies distributions in the inter-well areas. This geological characterization provides the framework of both large and small scale reservoir heterogeneity for reservoir flow simulations and subsequent future production predictions.

A classic geological model is first developed from structural interpretation of seismic data, literature review, detailed sedimentological core study and petrophysical analyses of 182 wells. By using petrophysically derived mineral concentrations, lithofacies distributions are determined automatically along each wellbore, thus providing quanti-fiable lithological data for statistical analysis. Then each reservoir unit with a distinct depositional facies ordering is analyzed using proportion curves and variograms to quantify the relative frequency and spatial continuity of each lithofacies in the unit.

The result is a combined grid- and object-based geostatis-tical model which, when simulated, provides a detailed three dimensional lithofacies distribution within the entire reservoir, which is consistent with the classical geological models.

The model honors the large scale deterministic unit maps and the vertical lithology distributions occurring in all wells.

This detailed geological description is then used as a basis for the full field simulation, as described in a companion paper addressing the dynamic behavior of the field.
A Global Algorithm for Pore Pressure Prediction
Authors: Scott David , Thomsen L. A.
Published: December 2007

The problem of prediction of in-situ pore pressure (ahead of the bit), on the basis of seismic data, has had a long history of study. It was recognized early that low seismic velocity in a given interval can be caused by high pore pressure in that interval. However, low velocity can also be caused by high porosity, soft lithology, or hydrocarbons, the occurrence of which may be correlated in-situ with high pore pressure. Hence the deduction of pore pressure from seismic information is formally non-unique.

Commonly used prediction techniques empirically fit some equation to a shallow "normally pressured" interval, then extrapolate to greater depths, comparing the observed interval velocity to this reference, independently at each depth point. Such a "point algorithm" reflects a physicist's view of the earth's layers as being independent, like samples in a laboratory.

Instead, we adapt a geophysical view, regarding the various layers as being coupled through geological proc-esses, in ways which we partially understand. Hence our prediction for the pore pressure in a given layer depends upon data from shallower layers as well. As a "global algorithm", it is embodied in a decision tree, rather than an equation. Since it is different in kind from other algorithms, it can offer independent corroboration of, or alternatives to their predictions. Using uphole VSP data acquired during drilling, it can refine its surface-seismic-based predictions below the bit. It can incorporate a priori information of any sort to condition its predictions.

Its predictions lead naturally to the delineation of "subsurface fluid compartments", ie zones several thousand feet thick, each with a local hydrostatic gradient and an elevated hydraulic head, separated by thin seals, with horizontal extents of several km to hundreds of km.

Worldwide applications show that its predictions can be useful for prospect evaluation as well as for drilling safety and efficiency.
Measuring Drilling Contractor's Performance
Authors: Ogidan Biodun , Coetzer Christopher
Published: December 2007

Interrupted (non productive) time caused by either contractor, operator or third parties will result in considerable loss of time and money. This paper describes a method used to record and analyze interrupted time in two broad categories — those due to improper procedure, and those due to equipment failure. The objective is to improve profitability by managing downtime associated with equipment failures and the application of incorrect procedures.

Identification of the most frequent occurring problems is paramount in the determination of corrective measures to reduce the defficiencies in the performance of the operations.

Major incidents (interrupted time greater than 6 hours) are an indication of the contractor's overall performance and are easy to measure by consolidating and maintaining a simple database of operations.

This paper deals with ways of measuring the drilling contractors' performance focussing on total interrupted time. The performance analysis incorporates data from 164 wells drilled (meterage 384,300) and 82 work over wells in Africa, South America and Europe, both land and offshore during 1991/1992.

An attempt is made to demonstrate that this type of approach has resulted in more efficient services by the contractor and shows that improvements in staff training greatly reduces downtime caused by incorrect operating procedures while a good preventive maintenance program reduces downtime caused by equipment failures.

As the oil industry shifts away from day rates to incentive type contracts, service quality assurance will become increasingly more important. A system of in-house auditing (service quality appraisal) and follow-up (rig/base management audit) has been found useful in gauging compliance with predetermined standards of performance.
Benefits of Complementary Surface Vibration and MWD Drilling Mechanics Measurements in a Horizontal Well
Authors: Robson M. S. , Fambon Luc , Sancho Jean , Sutcliffe B. C.
Published: December 2007

MWD measurements of weight on bit (WOB) and torque on bit (TOB) were used in conjunction with a surface drillstring vibration measurement sub to optimize drilling performance. This was performed in the horizontal section of a well drilled through fractured granitic basement below the normal producing zone of the Clair Field on the United Kingdom Continental Shelf.

Experience shows that surface drillstring vibration and MWD measurements complement one another, thereby providing a more comprehensive understanding of drilling dynamics in real-time. In turn, having additional information on downhole conditions allows the operator increased confidence in interpretation of drilling events as the well is drilled.

The downhole MWD tool provides measurements of torsional and axial strain. Due to MWD signal transmission rate limitations, the real-time data density is limited, and provides only a low frequency image of the drillstring behaviour. By contrast, the surface vibration sensors can use higher frequency measurements, although these may be less representative of conditions at or close to the bit.

The combined data sets were used to successfully identify and monitor prognosed fracture zones, drillstring component wear and energy transfer to the bit. In addition, vibration data allowed the operator to modify drilling parameters to avoid harmful resonant conditions in the drillstring which could have resulted in MWD and bit failure.

Evidence from this case study suggests that, with high frequency drillstring vibration measurements, the probability of detecting drilling problems using MWD drilling measurements can be much improved, leading to an overall increase in drilling efficiency and reduced costs.
Fully Retrievable, Slimhole Gamma Ray MWD System Minimizes the Risk of Horizontal Drilling
Authors: Genrich D. S. , Prusiecki C. J. , Dunlop F. L.
Published: December 2007

A slim hole gamma ray and directional surveying MWD tool has been developed specifically for real-time geosteering applications in horizontal wells. It is the first system which is totally retrievable and replaceable by slick line. This minimizes risks associated with stuck pipe and "lost-in-hole". In addition, it cuts costs by minimizing the number of round trips to change tools in case of failure.

The system can be run in drill collars with internal diameters as small as 2.19", and has been run in collars with 3 1/2" ODs. It has also been run in coiled tubing drilling operations.

This paper describes the downhole system and associated calibration procedures. Comparisons with conventional wireline logs are made.

Several field applications from horizontal wells are described. In particular we demonstrate how the gamma ray can be used to "geosteer" the horizontal drainhole to remain in the hydrocarbon section and track formation dips while drilling. This reduces the risks of horizontal drilling and increases payback potential
A Cementing Temperature Simulator yo Improve Field Practice
Authors: Guillot Frederic , Boisnault J. M. , Hujeux J. C.
Published: December 2007

It has long been known that temperature during circulation and after cement placement is one of the most important parameters for the design of a slurry and the success of cement jobs. Since API correlations do not take into account important parameters affecting the temperature evolution, simulators, which are sensitive to little known parameters, have been developed. This has made validation difficult or unconvincing, as there always exists a set of input parameters that can match observed temperature on a particular well. It has also significantly limited the widespread use of temperature simulators for field operations.

In this paper we present a cementing temperature simulator which has been developed taking this inherent difficulty into account. The validation was performed by testing against 30 jobs from the API database, selected based on data completeness.

With this simulator, temperature prediction has been considerably improved over the API method. The standard deviation, maximum overestimation and maximum underestimation have been reduced on the thirty API jobs.

This model applies equally well to onshore and offshore, vertical and deviated wells, and takes into account other variables that affect temperatures while cementing.
Effect of Casing Pressure on Gas Flow through a Sheath of Set Cement
Authors: Jackson P. B. , Murphey C. E.
Published: December 2007

This paper reports results of laboratory tests on structural behavior of cement as related to zone isolation. For a commonly used tail cement, rock mechanics type tests were obtained to get detailed stress-strain behavior. Near full scale laboratory equipment was used in two tests to simulate casing-cement-formation loading and behavior downhole. The internal casing pressure was increased in one test, decreased in the other. For the casing-cement-formation combination tested, both tests showed increased gas flow through the annulus after cyclic application and bleed off of casing differential pressure greater than 5000 psi.
Dynamic Spurt-Loss Beneath an Oilfield Bit
Authors: Walker B. H. , Black A. D.
Published: December 2007

While drilling or coring, freshly exposed rock is contacted by the drilling fluid and liquid mud filtrate spurts into the formation ahead of the bit before a substantial mud solids filter cake can be formed. In addition, mud solids and drilled up fines may penetrate the formation forming an internal filter cake or bridging zone. The amount of plugging from these solids affects the magnitude of the liquid filtrate spurting into the formation. This spurt-loss ahead of the bit tends to relieve differential pressure and chip hold-down effects at the bottom of the hole resulting in an increased penetration rate. In coring applications, the core is altered by the filtrate and solids and the pore fluid is exchanged with the filtrate which changes the fluid state of the core. This makes interpreting the core data very difficult after these events have occurred. The capability to measure and understand the spurt-loss phenomena is obviously very important. Since no satisfactory method existed for measuring spurt-loss, a machine was designed and constructed to measure spurt-loss under simulated downhole conditions. The system was partially funded by Drilling Engineering Association projects. The test machine and the procedures developed are described herein. The results of a series of spurt-loss tests with different drilling fluids, rock permeabilities and test conditions are also presented.
Slimhole Well Kill: A Modified Conventional Approach
Authors: Prince P. K. , Cowell E. E.
Published: December 2007

One of the major barriers to the introduction of slimhole drilling technology to oilfield operations was perceived to be the maintenance of safe standards of well control. There were two parts to this problem. First, the reduced kick tolerance in a small annular capacity well dictated that the kick detection system must be able to detect an influx of approximately one barrel. Second, conventional well kill techniques such as the Wait and Weight Method depend on the annular pressure losses being a small fraction of the total circulating system pressure loss, such that while not causing fluid losses in the open hole, a small overbalance is maintained above formation pressure. This assumption is often not valid in slimhole wells.

This paper presents a safe method of modifying commonly practiced conventional well kill techniques to take account of the high annular pressure losses and circulate out the influx in a controlled manner. Previous solutions to the slimhole well kill problem have depended upon unpracticed dynamic techniques where neither the position and volume of the influx nor the pressure applied to the wellbore are precisely known.

The paper will analyse the forces occurring during a well kill operation and derive modified well kill equations.

In addition, situations unique to the slimhole scenario such as the effect of annular friction pressure losses which are greater than the shut in casing pressure, their effects on MAASP and the behaviour of surface circulating systems will be discussed.

The paper will go on to describe how the modified procedure is implemented. This section will include details of the well control training programme developed and the pre-kick data collection procedures established at the slimhole rigsite.
Well Cost Systems Approach: Achieving Well Cost Reduction through Slim Hole Drilling with a Purpose Built Drillstring and Rig
Authors: Dupuis D. , Fanuel Ph.
Published: December 2007

The objective of Slim Hole drilling is to significantly reduce the well cost through reducing the hole and casing diameters below those conventionally used. The primary reduction can be realized through lower consumable cost, further significant reduction being achieved through a reduction in rig size. Drilling smaller diameter hole, however, has the drawback that penetration rates are reduced significantly. This effect counteracts the price reduction gained through smaller hole size and can even completely offset it. A key objective, therefore, for Slim Hole drilling is to develop a mechanism which permits the drilling of small diameter holes at conventional rates. This paper discusses the development of a total system designed to maximise the reduction in well cost as an integrated project. The project is titled EUROSLIM.
Slimhole Exploration: A Case for Partnership in the Nineties
Authors: Murray P. J. , Spicer P. J. , Jantzen R. E. , Syrstad S. O. , Taylor M. R.
Published: December 2007

Slimhole drilling technology offers the potential for a major reduction in costs and exploration risk in remote, environmentally sensitive areas, especially when coupled with wellsite continuous coring. High quality geological information from continuous slimhole wellsite core analysis can be acquired at significant cost reduction compared to conventional drilling. In January 1990, BP identified slimhole drilling as a technology for its exploration strategy in the 1990's. However, it was perceived that there were technology barriers which might hinder implementation, including the availability of wellsite core logging and early kick detection services.

In January 1991, EXLOG was invited to help address these issues for a project due to commence in January 1992 in Africa. Pre-tenders were requested in early February 1991, followed by formal tenders in August 1991. A period of brainstorming was followed by interactive concept developments involving drillers, engineers, and geoscientists. During 1991, STATOIL formed a strategic alliance with BPX, and a "Slimhole Drilling Venture" formed to develop the core logging service. After a technical audit of the three parties, a joint development strategy was begun in midAugust 1991, using specialists from all parties, complemented by a team of co-contractors on three continents. A heli-transportable system was developed, with bench tests completed by mid November 1991.

Slimhole kick detection was addressed in a different cooperative manner. Researchers from both BP and EXLOG worked on rapid-prototyping an existing off-line wellbore fluids research model for conventional holes and converting it into an on-line, slimhole, early kick detection wellsite system. BP supplied the science and EXLOG supplied a real-time wellsite information management platform on which to run the model within the data analysis unit. Data from another operator's research well was acquired to provide a unique data set for model evaluation. A novel flow sensor was purchased for wellsite evaluation.

The application of these concepts was successfully evaluated in field trials during a four well exploration program. The initial evaluation of the core logging procedure indicated that high quality, practical, repeatable measurements can be made in near real-time in remote environments. Rapid reaction to flow anomalies using the early kick detection system contributed to significant cost savings. The stage is now set for project/business driven, safe application of slimhole continuous coring in remote exploration.
Adaptation of Slimhole Well Design to a Horizontal Well
Authors: Foster Leigh
Published: December 2007

Development drilling on the Pickerill gas field in the UK Southern North Sea (SNS) began in May 1991. During the drilling phase a potential requirement for a horizontal well was identified. The original field slim-hole casing design incorporated only the minimum number of casings required for the drilling of conventional slant wells. The horizontal well was planned as a side-track from a pilot hole, drilled to assess reservoir quality and structural elevation.

The drilling programme was chosen to meet the requirements of the reservoir engineering, geology and drilling departments. The geologists required real-time logging-while-drilling (LWD) tools to be used through the reservoir, to ‘steer’ the directional driller up or down into the most productive zones. These tools were not available for 6" hole, so an 8½" hole was essential.

Nearly 2600 feet were successfully drilled at over 80° inclination, the first time in the SNS that a horizontal well had been drilled through the reservoir, without previously casing off the overlying evaporite sequence.

After the hole was drilled, two production liners were run; a 7" string cemented above the reservoir, and a 5" preperforated string left uncemented across it. The success of this well opens up new possibilities for cost reduction in horizontal wells in the SNS, as it proved it is possible to drill a horizontal well using the same basic casing programme as a conventional well.

The slim-hole well design used on the field is described, and how this was modified for the horizontal well. The results of the execution of the plan, and conclusions regarding its success are presented.
Mud/Shale Interaction: Model Wellbore Studies Using X-Ray Tomography
Authors: Cook J. M. , Goldsmith Garry , Geehan T. M. , Audibert A. M. , Bieber M-T. , Lecourtier Jacqueline
Published: December 2007

A novel piece of equipment allows the monitoring of wellbore processes as they occur, under realistic downhole stresses, using computed X-ray tomographic scanning (CT scanning). It has been used to study the interactions between shale and drilling fluids, using a variety of fluid chemistries and pressure regimes.
Equity in Drilling Contracts: Responding to Operator and Contractor Concerns
Authors: Moomjian C. A.
Published: December 2007

This paper discusses conceptual aspects of certain major drilling contract terms. The respective objectives of operators and contractors are assessed in reviewing key contract issues.

Subjects of this paper applicable to all daywork drilling contracts include contract extension options, commencement date provisions, termination provisions, rate structure, liability/indemnity allocations and insurance obligations. In respect of contracts for international operations, the analysis includes a review of provisions addressing currency fluctuations, political risks, local taxation and customs duties. In regard to long-term contracts, provisions addressing rate adjustment for cost variations and early termination compensation are evaluated.

This paper emphasizes the respective individual concerns and objectives of operators and contractors and attempts to seek a "common ground" upon which the principal contract terms can be addressed in a fair and equitable manner to provide a sound contractual framework for a successful drilling program.
The Effect of Unplanned Operations on Drilling Performance Evaluation
Authors: Peterson S. K. , Pearce D. W.
Published: December 2007

This paper presents results of an interpretation and statistical analysis of two years of drilling data, concentrating on the effects change-of-scope (COS) operations have had on drilling performance and drilling performance evaluation. The analysis shows that COS activities do not accurately represent drilling performance, and that COS costs may unjustly influence conventional cost-related measurements of drilling performance.
The Development of a Competency-Based Training Programme for Drilling Engineers Using Quality Assurance Principles
Authors: King G. W.
Published: December 2007

A new training programme for Drilling Engineers has been developed by a North Sea Operator. The programme has been designed: to overcome the limitations of existing training practices; to meet the business needs of the company for Drilling Engineers; and to be capable of being audited. Training models from other industries and the concepts of ‘quality systems’ were used in the development of the programme. The result is a formal training programme supported by endorsed training records and formal accreditation.
How Surface Hole Drilling Performance Was Improved 65%
Authors: Russell B. A.
Published: December 2007

This paper describes how improved performance was achieved drilling large diameter surface holes through hard formations prone to severe loss of circulation. The paper is based on field experience in Yemen. Modified hammer bit designs and powerful construction-industry hammers were used to significantly increase penetration rates. High rates of penetration demanded an effective cuttings removal medium. A polymer-enhanced foam system was chosen for this purpose, and it successfully cleaned cuttings from the hole at the highest rates of penetration. By changing foam properties, air injection rate, bit design, hammer size and the depth at which the hammer drilling assembly was replaced with a rotary drilling assembly, the time required to drill surface holes was reduced by 65%.
Systematic Tracking of Fatigue and Crack Growth To Optimize Drillstring Reliability
Authors: Howard J. A. , Halbert M. E. , Lubinski Arthur
Published: December 2007

API RP7G contains guidelines to determine if drillpipe fatigue damage might occur due to dogleg severity. The results are complicated and difficult to use, making them impractical for applications involving non-constant rotary speeds and rates of penetration. Furthermore, inspection guidelines based on expended fatigue life have not been developed.

This paper presents a systematic method of tracking cumulative fatigue of each joint of pipe while drilling a well, and it links the results to recently published work on crack growth for determination of inspection intervals. Results are presented for an example offshore well, and sensitivity cases are run that illustrate how fatigue and crack growth can become significant within a single well.

The tracking system can be used both in planning and during drilling. Critical drillpipe lengths and potentially damaged joints are determined, and inspection frequency is optimized. Operators, drilling contractors, and inspection companies can: a) design drillstrings, deviation programs and drilling parameters to minimize fatigue, b) perform inspections on either all of a string, or selected portions, as dictated by actual hole and drilling conditions, and c) monitor fatigue in real time using actual drilling information.
Slimhole Drilling Saves Dollars in Thermal Injectors
Authors: Grove G. A. , Vervloet A. W.
Published: December 2007

Recent advances in slim-hole drilling techniques are being used to drill shallow steam injectors in the San Joaquin Valley area near Bakersfield, California. The use of 2-3/8″ tubing as the casing string along with using a workover rig to drill the injectors has resulted in significant savings in required capital. Results from the latest work shows that a 50% reduction in total well cost can occur when drilling a multiple injector package.
Forecasting Steam Chest Growth in a Line-Drive Steamflood Project Using Classical Analytical Models
Authors: Hutchinson D. A. , Fattahi Behrooz
Published: December 2007

The rate of steam chest growth can significantly impact oil production in a line drive steamflood. Simple analytical models often suffice to provide the quick insight needed to analyze the growth rate and save major numerical simulation efforts.

Using classical analytical models proposed by Marx-Langenheim, Mandl-Volek, etc., steam chest growth is analyzed and predicted in the Upper Vedder sand at Mt. Poso field, California. Various steam injection scenarios are examined.

When compared with field data, the analytical results indicate accurate description of the steam chest growth. The predicted rate of steam chest growth is presented and the future performance of the reservoir discussed.
Optimal Choice of Completion Intervals for Injectors and Producers in Steamfloods
Authors: Chu Chieh
Published: December 2007

This work studies systematically the effects of completion intervals of both injectors and producers on steamflood performance and seeks the optimal choice of the completion intervals. Simulation results showed that, in the absence of deterministic shales, the optimal choices will improve the steamflood performance, significantly in many cases.
A New Method of Steamflooding Oil Reservoirs Using Staggered Scheduling of Injection/Production Oscillations
Authors: Chu Chieh
Published: December 2007

A new method of steamflooding has been suggested which uses staggered scheduling of oscillations in injection and production among the various injectors and producers in a project. Simulation results show that the proposed method can increase oil production over the base case of no oscillation by 2-8 %.
Steaming and Operating Strategies at a Midlife CSS Operation
Authors: Gallant R. J. , Stark S. D. , Taylor M. D.
Published: December 2007

Imperial Oil Resources Limited began pilot experimentation with Cyclic Steam Stimulation (CSS) at Cold Lake in 1964 and followed this with commercial application in 1985. Since that time an extensive amount of experimental data and operating experience has been acquired which has resulted in the continual evolution of steaming and operating strategies for CSS.

Optimization of the many process variables involved in CSS is complex due to their interdependency. The optimization of steaming and operating strategies has advanced significantly with commercial development and continues to evolve as the CSS process matures and the reservoir reaches more advanced stages of depletion. This evolution has focussed on steam strategies to manage interwell communication and increase areal conformance, and operating strategies to maximize the efficiency of producing mobilized bitumen which lies at ever increasing distances from the wellbore. The continued success of CSS in Cold Lake is dependent on the continued improvement of these steaming and operating strategies.
The Orinoco Heavy-Oil Belt Pilot Projects and Development Strategy
Authors: Trebolle R. L. , Chalot J. P. , Colmenares Rodolfo
Published: December 2007

The development of the Orinoco extra heavy oil belt (Faja Petrolifera), known as the largest extra-heavy (8.5°API) hydrocarbon accumulation in the world, has become a major goal for the Venezuelan oil industry in the next decade.

The Cerro Negro area, contains 213 billion stb and the current estimation for the primary recovery factor is 12% of the stock-tank original oil in place (STOIIP).

Following the exploratory campaign, in the early eighties, three pilot projects were initiated (0-16, J-20 and K-20) in the Cerro Negro Area. These pilots consist of patterns of vertical producing wells and clusters of highly deviated wells with different spacing, completion type, sand control, stimulation (huff and puff) and lifting process. Furthermore, since 1990 two horizontal wells were drilled, evaluated and monitored in cold production, using the neighboring vertical wells.

The acquisition of an exceptionally large data set in the exploration/appraisal step (207 wells) and the three pilot projects (155 wells) not only provided a unique opportunity for thorough study each of the relevant disciplines involved in the reservoir management and production facilities design, but also promoted a set of new technologies to be applied in the design of the commercial development of these prolific extra heavy reservoirs.
Differential Depletion in Heavy-Oil Sands, Lagunillas, Venezuela
Authors: Campagni Rita Delli , Alcalá Venecia , Nieves Israel
Published: December 2007

Cyclic steam stimulation has proven to be an effective and flexible process for recovering heavy oil. However, similar to the other projects in the Bolivar Coast Field, vertical steam distribution in the Laguna reservoir is poor due to thicker pay zone divided into two different main sand bodies, an upper sand unit a lower sand unit. Difference fluid and rock properties for the lower sand have contributed to production, meanwhile, the upper sand stayed at original conditions.

This work illustrates how an interdisciplinary team can set up new approaches to a mature reservoir, in order to optimize the exploitation of heavy oil sands. This approach was within the context of areal definitions, steam soak scheduling and production forecast. It was concluded that the Laguna upper sands should be treated as an individual reservoir.
Critical Flow Properties of Wet Steam
Authors: Chien Sze-Foo
Published: December 2007

Wet steam, being a two-phase fluid, has complex critical flow properties. Analytical and experimental data were used to investigate the critical steam flux, and the pressure ratio needed to achieve critical flow for a variety of popular flow-rate controlling devices. Three new parameters –– critical steam flux ratio, dimensionless critical steam flux, and the Napier parameter –– are introduced to correlate the critical flow data. Attention was focused on the effects of stagnation pressure, stagnation quality and design of the flow-rate control device on the critical flux. The study covered stagnation pressures from 200 to 2100 psia and stagnation qualities from 20 to 100%.
Parametric Study of the Design Factors for Cyclic Steam Injection in Lake Maracaibo Oil Fields
Authors: Trebolle R. L. , De Paz M. C. , Martinez D. E.
Published: December 2007

Cyclic steam injection has been performed since the early 60's in Lake Maracaibo reservoirs. The design parameters for a cycle have been generated from performance data gathered from stimulations of over 500 cycles. However, these design parameters include some statistical dispersion that might prevent attaining an optimum cycle design. While obtaining operating experience, Lagoven has also been using and developing numerical models to improve and optimize the cyclic-steam operating strategy.

A simulation and sensitivity study of the design parameters for the cyclic steam injection in the Bachaquero-01 reservoir was performed to determine more accurate values than those obtained from field operations only.

These parameters are injection rate, heat or steam input, steam quality and soak time. Additionally, analyses were made of reservoir behavior during steam drives, gas injection with steam, heat transfer between layers and an investigation of the use of horizontal wells for oil recovery by steamflooding and cyclic steam, using a fully implicit thermal simulator.

The results of 3-D simulations mainly showed that horizontal well patterns improved productivity. Besides improving the reservoir volumetric sweep efficiency, use of horizontal wells has the advantage of requiring fewer wells per area swept, projects being completed in a significantly shorter time.
Credibility in Forecasting and Planning or Why Should Management Use an Analysis of Uncertainty in Their Investment Decision Process?
Authors: Tobin J. C.
Published: December 2007

Gone are the days when simply finding oil and producing it were sufficient to achieve wealth and fame. The oil man can no longer make money in spite of himself. Investors demand that sound business decisions be made. This can only be accomplished if a thorough and credible assessment of uncertainty is included in the decision process.

The industry has long recognized and in many cases analyzed the uncertainties in the physical aspects of a project. However, investment decision must also recognize the economic uncertainties associated with the project. Therefore, such economic factors as oil price should be forecasted in terms of an appropriate range of confidence and evaluated together with the other uncertain project variables. It is this recognition of uncertainty that gives credibility to forecasting and planning activities. This paper will emphasizes three ways in which credibility can be established, Communication of uncertainty and Insight.
An Optimization Model for Allocating Capital to Exploration and Production Operations
Authors: Burness G. C. , Gupta R. K. , Novotnak J. F.
Published: December 2007

Capital allocation plans are being analyzed within the exploration and production group of an integrated oil and gas company utilizing information from a mathematical model which determines optimal allocations of single and multi-year capital outlays to exploration and development projects. The optimization processes focus on key performance drivers which better relate to enhancing shareholder value than more traditional accounting measurements such as net income, earnings per share, and return on assets. Key strategies for successful implementation of the model are discussed.
Recent Improvements in State Regulatory Programs and Compliance Practices
Authors: Smith G. E. , Smith W. R. , Littleton D. J. , DOE U. S. , Simmons Jerry
Published: December 2007

The U.S. Department of Energy (DOE) and the Interstate Oil and Gas Compact Commission (IOGCC) are sponsoring a joint study to examine the changes in State regulatory programs and waste management practices since the mid-1980s, focusing on 17 States that reflect the diversity of Lower-48 E&P operations. This paper documents the preliminary findings of that study, which is expected to be completed Spring 1993. In 1987, the U.S. Environmental Protection Agency (EPA) identified what it felt were gaps and areas of concern with State regulatory programs for the management of oil and gas exploration and production (E&P) wastes, although it found State programs to be generally adequate. Included in the paper is an overview of the concerns expressed by EPA in 1987, a review of the budgets and staffing commitments of these 17 States to oil and gas regulation over time, and a review of the specific regulatory modifications made by the States since the mid-1980s to improve waste management and environmental protection associated with oil and gas E&P operations. The evolution of the waste management practices used by oil and gas operators since the mid-1980s is also briefly discussed.
Pollution Prevention and Waste Minimization Opportunities for Exploration and Production Operations
Authors: Derkies D. L. , Souders S. H.
Published: December 2007

In a continuing effort to encourage improvements in the management of exploration and production (E&P) wastes, the Office of Solid Waste (OSW) of the U.S. Environmental Protection Agency (EPA) is identifying practices and technologies that may contribute to pollution prevention and waste minimization when applied to E&P operations. The sources of this information include trade literature, product literature, and patents. Once identified, details of these practices and technologies may be compiled in a database where the information may be easily accessed and ultimately used in the development of outreach materials for industry.

Several notable practices and technologies identified to date are discussed in this paper along with results of field trials where available. Although many have already been described in the literature, the intent of the authors is to present a brief overview of selected pollution prevention and waste minimization concepts in order to stimulate further investigation and discussion.