bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design Of Special Cement Systems For Areas With Low Fracture Gradients
Authors: Wieland D.R. , Calvert G.D. , Spangle L.B. 
Published: December 2007

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

ABSTRACT
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

Abstract
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

Abstract
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.