bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Production on Chalk Failure in the Valhall Field
Authors: Hermansson L. , Gudmundsson J. S. 
Published: December 2007

ABSTRACT
Chalk failure in six production wells without gravel pack in the Valhall field are observed to occur in two main periods, the early and the late. Early-period failures are related to pre-existing natural damage of the formation and wellbore operations such as drilling and well completion/perforation. Late-period failures are related to depletion in reservoir pressure. As pore pressure falls the effective stress on the formation chalk increases until its yield stress is reached. Early and late-period failures are both triggered by stresses related to pressure gradients in the formation near a wellbore. Shut-in and re-opening of production wells, for example, give rise to high pressure gradients that cause chalk failure. Fluid production below the bubble point also triggers chalk failure. The analyses of 19 chalk failure incidents are expressed in a conceptual damage-release model.
Hydrates: Towards The Complete Solution
Authors: Kalli C. J. , Cowie D. 
Published: December 2007

ABSTRACT
The economic development of many multiphase flow production systems requires a full understanding of hydrates and their control. BP Exploration has recognised this and has set itself the goal of developing the necessary understanding and ability to deal with hydrates and hydrate forming systems.
Three key areas have been targeted for investigation to develop the tools necessary to optimise the economics of hydrate forming systems. An important advance by BP in the first of these key areas is presented. The new BP phase equilibrium hydrate formulation is used to rigorously examine options for using a range of pure and mixed inhibitors.
Simulation Studies of Gas-Injection into Gas-Condensate Reservoirs
Authors: Diamond Luis , Rondon Cesar R. 
Published: December 2007

ABSTRACT
The effects of gas injection into two gas condensate reservoirs in eastern Venezuela were analyzed in order to establish optimum exploitation schemes. One of the reservoirs, the M3U sand, MVR-52, in the Zapatos field, is actually subjected to a pressure maintenance process. The other reservoir, the S3M sand, SG-44, in the Mapiri field, is a dual gas condensate, black oil reservoir, currently at a primary depletion stage.
Sensibility studies were made for both accelerated natural depletion and pressure maintenance through the injection of lean gas. These simulation studies were made utilizing a phase behavior simulator and a compositional simulator (COMPSIM). The first was used to calculate equilibrium constants at different pressure. In order to achieve this, it was necessary to characterize the fluids in function of six (6) pseudocomponents, which represent the mixture of the pure components as given by PVT analysis.
COMPSIM is a three-dimensional, three-phase, compositional simulator, which allows to compute pressure and saturation distributions, as well as the distribution of the fluid components in the oil gas-condensate phases. Mass exchange of each component between oil and gas phases is ruled by the equilibrium constants under conditions of thermodynamic equilibrium.
In the case of the M3U/MVR-52, after introducing pseudocomponents for the characterization of initial fluid compositions, the dew point pressure, liquids deposition and relative volumes were matched using the compositional phase simulator. Production and pressure history matching were attained through the COMPSIM.
The S3M sand, SG-44 reservoir also belongs to the lower section of the Oficina formation of lower Miocene age. The depositional environment consists of a north to south oriented deltaic channel at the center of the reservoirs, and splays with poor sand development toward the borders.
The S3M is a well defined, homogeneous sand body, thinning out to the east and to the west. Due to its depositional environment the sand shows little variations in thicknesses.
The reservoir is bounded to the north by a water-oil contact, to the east and west by changes of facies and to the south by a fault, Fig. 3.
Interpretation of Pressure Behavior of Fractured, Deviated, and Horizontal Wells
Authors: Soliman M. Y. 
Published: December 2007

ABSTRACT
This paper discusses the determination and interpretation of fracturing pressure data when the well is deviated or horizontal. The first part of the paper deals with microfrac and minifrac tests on deviated wells while the second part deals with initiation pressure of a transverse fracture intercepting a horizontal well.
Microfractures are usually performed on vertical wells to determine the minimum horizontal stress while minifractures are performed to determine leakoff coefficient. Because a vertical well is in the plane of a vertical fracture, determination of horizontal stress is fairly straightforward. If the well under investigation is deviated, it may not be in the plane of the vertical fracture. Consequently, a fracture may start along the axis of the well as a deviated fracture. At a distance from wellbore it may be realigned in the vertical direction. Because this realignment may affect the observed fracture closure pressure, a larger than conventional microfracturing treatment may be necessary.
This paper reports on tests in which both microfracture and minifracture treatments were performed on a deviated well. The observed closure pressure microfracturing and minifracturing supports the above hypothesis. All pertinent information and analysis for this deviated well are presented.
If the well is horizontal and the fracture intersects the well (transverse fracture), the Hubbert and Willis criterion for fracture initiation may not apply. In this paper, Hoek and Brown failure criterion is used for transverse fractures. The criterion better models and explains the high initiation pressure observed in both field and laboratory.
This paper gives the stress analysis for a horizontal well prior to fracturing. The failure criterion is then discussed and applied to explain laboratory observations.
Fractured Reservoir Evaluation Using Production Testing
Authors: da Prat Giovanni , Jorquera Ricardo , Puthigai Suresh 
Published: December 2007

ABSTRACT
In this work the production testing techniques used for fractured reservoir identification and characterization are presented. For the sake of technical synergy a brief summary is given in open hole logs techniques used for fractured reservoir detection.
The evaluation of different types of production tests conducted in these reservoirs is explained using field data examples. It is also presented as a special case the solution for the pressure behaviour of a well completed in a reservoir where in natural fractures occur over a limited area around the wellbore. A new set of types curves are presented that are quite resolutive for fractured reservoir identification specially for the diagnostic of the flow regime associated to the interporosity transient behavior that is so important for reserves estimation. Also included are the regression methods applied to these systems. As a main conclusion derived from this work is that a combined approach between geology and reservoir engineering is needed for a proper evaluation of these systems.
Large Amplitude Displacements of a Deepwater Moored Floating Offshore Platform
Authors: Morooka Celso K. 
Published: December 2007

ABSTRACT
Large amplitude displacements of deepwater moored floating offshore platform are here discussed. A brief description of typical moored floating systems is made.
Environmental forces which cause the platform motions are described. A motion simulation procedure in time domain is evaluated and results are presented for two different floating systems. Computer simulation results are compared with experiments.
From the present study, it is concluded that the prediction of large, amplitude displacements of floating off shore platforms could be estimated by time domain simulations. These results are very important for mooring designs and for safe offshore drilling and production operations.
Wave Attenuation in Acoustic Logs and Formation Permeability: Case Studies and Experiences
Authors: Perarnau Adrian , Flores Decio , Martinez Oscar 
Published: December 2007

ABSTRACT
Full waveform acoustic logs can be used to study the attenuation of body (compressional and shear) and surface (Pseudo-Rayleigh and Stoneley) waves in rock formations around the wellbore. Neglecting fractures, and for a given geometry, it is widely accepted that body waves are attenuated mainly because of viscous flow in the pores. At the same time, Stoneley wave attenuation seems to be related to flow of mud-derived fluids in and out of the rock frame during wave passage. Apart from the factors previously mentioned, there is a strong dependence of wave attenuation with lithology, especially clay content. This is shown here by simple calculations of wave energy in field logs. Clay volume, therefore, must be taken into account if wavetrains are to be used in the identification of highly permeable strata. To detect zones with significant hidraulic conductivity (rocks with high permeability, in relative terms, saturated with low-viscositv fluids), a simple index is proposed. The index I measures the amount of low frequency energy 'corrected' by clay volume using the traditional GR log. The correlation between I and oil production, in recently-drilled wells in northeastern Venezuela, is strong, even when traditional log analysis shows no differences between the perforated pay zones. The simple type of calculations proposed here are suitable for the quick look kind of presentations used during perforation design. They are, however, of local significance and its relation to true permeability is obscure due to variability in fluid type and saturation. Other methods, more meaningful although time consuming, are in study.
X-Ray Shadowgraph Studies of Areal Sweepout Efficiencies
Authors: Slobod R.L. , Caudle B.H. 
Published: December 2007

Published in Petroleum Transactions, AIME, Volume 195, 1952, pages 265–270.

Abstract
In the past, the main emphasis in attacking the problem of the recovery of oil has been on the determination of fluid flow characteristics and residual oil saturation in the part of the reservoir which is contacted by a displacing phase. It is recognized that the determination of the fraction of the reservoir contacted in secondary recovery operations is also of great importance in predicting the ultimate recovery to be expected. A method is described in which radiographic techniques are used to determine these areal sweepout factors for any type of well spacing. Data showing the relationship of viscosity ratio and relative permeability to areal sweepout efficiency are presented for the five spot and the direct line drive well spacing patterns. Further applications of the method to studies of the displacement efficiency in the area contacted are mentioned.

Introduction
The problem of increasing oil recovery from typical reservoirs is generally attacked by trying to devise some means for reducing the residual oil in that part of the reservoir which is contacted. The fraction of the reservoir contacted in the displacement process, however, is also of major importance but has been given less consideration in the past.
Relative Permeability from Centrifuge and Unsteady State Experiments
Authors: Munkvold Fridtjov Ravn , Torsaeter Ole 
Published: December 2007

ABSTRACT
Relative permeability measurements have been conducted using the unsteady state and the centrifuge methods. The drainage of oil with gas was performed on water-wet cores containing irreducible water. An automated measurement system has been developed for the centrifuge experiments. The automated system is of vital importance for the measurement of rapid fluid production, and exhibits excellent performance in data collection compared to manual reading. The oil relative permeability curves calculated from the two methods are comparable only if flow potential is kept equal in the two flow processes during the experiments.
Gel Strength as Related to Carrying Capacity of Drilling Fluids
Authors: Machado José Carlos Vieira , Aragão Átila Fernando Lima 
Published: December 2007

ABSTRACT
It is known that the plastic Bingham model is inadequate to represent some types of drilling fluids1,2, such as low solids and emulsions, especially at medium and low shear rates. Previous experiments on carrying capacity concluded that the average annular velocity and rheological properties affect the fluid transport more significantly than other parameters. Many of these experiments3,4,8,9 refer to the yield point of the Bingham model, calculated at high shear rate, as the most important parameter.
This experiment studies how the initial gel strength and plastic yield point affect the carrying capacity of the drilling fluids, employing the transport ratio concept. For this purpose the terminal settling velocity of the drilled solids through quiescent fluids was experimentally determined. The results showed a better correlation with the initial gel strength than with the yield point. Also, the analysis of the results demonstrated that a gel strength of about 1.92 Pa (4.0 lbf/100 ft2) is necessary and substantial to obtain a transport ratio higher than 0.50 when the annular velocity is in the range of 0.41 m/s (80 ft/min) to 0.66 m/s (130 ft/min), using low solids and polymer drilling fluids.
For any type of water based drilling fluids, a gel strength in the range of 3.35 Pa (7 lbf/100 ft2) to 4.79 Pa (9.0 lbf/100 ft2) is sufficient to remove the cuttings at more than 0.50 of transport ratio, even when the annular velocity is about 0.25 m/s (50 ft/min).
Temperature Profile of a Fluid Flowing within a Well
Authors: Boas Mario Barbosa Villas 
Published: December 2007

ABSTRACT
This work makes a review in the literature about thermal transference fenomena within a well. It proposes an improvement of a model proposed before which allows it to be applyed to complex well geometrics. Some simulations are made and the results are discussed and compared with the ones obtained by API method. The influence of some parameters not considered by API methods are also discussed.
Computerized Well Analysis
Authors: Podio A. L. , McCoy J. N. 
Published: December 2007

Abstract
A system has been developed based on a powerful portable microcomputer and an integrated data acquisition package which allows real-time visualization of pumping well performance.
The system combines all the necessary elements to obtain a complete analysis of the performance of the pumping system which includes the pumping unit, the wellbore, and the reservoir.
The data acquisition package is connected to the expansion slot of the computer and consists of the necessary analog and digital channels to process data from standard transducers such as acoustic, pressure, temperature, rod load, displacement etc. Detailed surface unit performance curves such as dynamometer, speed, acceleration, power etc. can be obtained and analyzed. When the instrument is used in conjunction with an acoustic pulse generator and receiver, it digitizes and stores the reflected acoustic signals which are digitally filtered and automatically processed to determine the liquid level. This is undertaken under program control so that a continuous recording of fluid level vs. time is obtained along with the pumping unit performance parameters. Fluid level data is processed by the software to calculate bottomhole pressure as well as flow into and out of the well bore. Changing the well from flowing to shut in conditions allows recording of pressure of reservoir parameters.
The Well Visualization display can be used as a diagnostic tool to optimize pumping well performance on a periodic basis. The present performance of the well is compared to its recorded past performance and in the case where significant differences are noted, a more detailed analysis is undertaken to recommend changes in operation or remedial actions. In critical well applications, the system can function as a stand-alone dedicated controller.
In Situ Formation Wettability Determination in Depleted Zones
Authors: Desbrandes Robert , Bassiouni Zaki , Gualdron Jorge 
Published: December 2007

ABSTRACT
Most rocks ore normally water-wet. However, If the rock has been in contact with crude oil, the coating of the grains with asphaltenes and resins may change the wettability from water- to oil-wet. This change cannot be overlooked since wettability affects such properties as capillary pressure, relative permeability, and electrical resistivity. Besides its effect on formation properties, wettability plays an important role in recovery mechanisms.
The technique developed previously for in situ wettability determination at the oil-water contact level has been extended to the movable oil-residual oil contact level. Some formations contain a residual oil saturation below the movable oil level due either to a gradual escape of the hydrocarbons through the upper confining layer during geological time, or to efficient water encroachment.
Experiments conducted in a water-wet sand pack have shown that, in the residual oil zone, the water pressure gradient is recorded up to the movable oil level where it changes to the oil gradient. The free water level is located below the gradient change and can be determined at the intersection of the oil and water gradients.
In an oil-wet sand pack initially saturated with oil, the experiments show the pressure gradient changing from the water gradient to the oil gradient at the movable water level, which is located below the free water level. The shape of the pressure profile can be used to qualify wettability. The pressure data can also quantify wettability using the J-function method.
Wettability determination in situ is possible with a formation pressure profile recorded with a wireline formation tester. An example is shown in which the contact angle is calculated.
Formation pressure profiles recorded in the oil-water transition zone in wells with a residual oil saturation yield information on the wettability of the formation and the position of the movable oil level.
Development of Flexible Pipe for Sour Fluid Service
Authors: Fuku Tadashi , Goto Yasuhiro , Yamaguchi Takumi , Ishii Kenichi 
Published: December 2007

ABSTRACT
Flexible pipes used in offshore oil production 1, 2, 3 are kept watertight by a plastic sheath, with the result that their reinforcement steel never comes in contact with the fluid that is transported in them.
But since various gas components permeate the plastic layer, there is some concern that the hydrogen sulfide in a sour environment could cause sulfide stress corrosion cracking (SSCC) or hydrogen induced cracking (HIC).
By special processing and heat treatment we have developed steel wire having a fine spheroidized structure, and in SSCC and HIC withstand tests we have confirmed that no cracking occurs even after bending and welding.
Satisfactory test results have been obtained with flexible pipe made from this material.
Formation Evaluation of a Horizontal Well
Authors: Najia W. K. , Habib K. H. , Asada J. 
Published: December 2007

ABSTRACT
In Upper Zakum Field, the interest in horizontal drilling has continued. A second horizontal well was drilled during the second half of 1989. This necessitated running logging tools for well control and to evaluate the reservoir characteristics. The logging tool selected for this well is that of Sperry-Sun. Tools configuration and tolerance were found to fulfil ZADCO's requirements and specifications.
The services provided included Measurement While Drilling (MWD) directional services and RLL (Recorded Lithology Logging). The RLL services cover Dual Gamma Ray (DGR), Electromagnetic Wave Resistivity (EWR) and Compensated Neutron Porosity (CN porosity). All the RLL tools were an integrated part of the Bottom Hole Drilling Assembly. Data acquired while surveying was recorded in a recording sub down-hole and retrieved when the tools were up at the surface.
A PC assisted quick look interpretation was carried out using Archie's equation in shale free limestone to calculate:
Effective porosity Water Saturation and Bulk water volume.
Reservoir characteristics as derived from the RLL were compared with near-by wells and geological maps and were found compatible with the in-use Geological/Reservoir model.
Approach to Emergency Pipeline Repair System
Authors: Binthabet Hussain A. , El-Shenawy Maamoun 
Published: December 2007

Abstract
ADMA-OPCO has main subsea pipelines in sizes ranging from 16" to 48" Dia with approximately total length of 275 km through which crude oil, gas and condensate are transmitted from Umm Shaif and Zakum Fields to Das Island, north west of Abu Dhabi, for processing and loading.
These pipelines are vital, considered the nerve system of ADMA-OPCO production facilities and are the only source of gas supply to ADGAS' LNG plant. Hence their availability and reliability is the prime factor in ADMA-OPCO's and ADGAS' productivity.
Having noted that recently Abu Dhabi offshore areas have had quite an increasing number of reported pipeline incidents, the possibility of a pipeline failure resulting from seafaring traffic, operation and materials can never be ruled out Such failure can lead to prolong production down-time especially if an operator is not adequately equipped to cope with such an emergency failure.
Digital Control Systems for Oilfield Operations
Authors: Heraiba F. A. 
Published: December 2007

ABSTRACT
Development of UPPER ZAKUM Field entails the use of an advanced computerised control system. The system comprises SCADA; Distributed Control System (DCS) and Programmable Logic Controllers (PLC).
The system provide the operators with an efficient and flexible tool for remote and automated operations; featuring economical cost, reliable control and better operating performance.
After arranging in depth training for the operational and maintenance groups, the operating personnel accepted the system and continued to operate it efficiently.
Development of the Naturally Faculted ISND Shuaiba Reservoir
Authors: Buksh G. 
Published: December 2007

Abstract
This paper describes the Idd el Shargi North Dome (ISND) reservoir located offshore Qatar. Production performance of this carbonate oil reservoir, intensely faulted in the crestal area, is summarised.
A phased development plan of the reservoir is presented, which consists of gas/oil gravity drainage in the crest and pattern water flooding in the flanks.
AVO Techniques for Carbonate Reservoir Characterization
Authors: Poster C. K. , Buchan I. C. 
Published: December 2007

ABSTRACT
AVO (Amplitude-vs-Offset) is a seismic technique which examines how reflection events change with varying angles of incidence of the seismic waves. This change is related to elastic properties of the reflecting formation, which may be associated with particular fluid saturation and lithology conditions.
In this paper, a data set composed of well logs and a coinciding surface seismic line are used to evaluate the AVO technique for a major Gulf carbonate reservoir. From the logs, Poisson's ratios were calculated and combined with a log-based stratigraphic model to estimate the AVO response of the reservoir formations. Specifically, the amplitude gradient curve for a zero phase response with increasing angle was calculated. The surface seismic data was processed for a comparable AVO result. Combined interpretation of the two indicates possible changes in the oil reservoir across a structure. One conclusion is that AVO interpretation without reference to valid physical models is very difficult.