bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extreme Production Logging in Long Horizontal Wells with High Flow Rates using Downhole Tractors
Authors: Castillo H. C. , Turner D. R. , Smalley E. A. 
Published: September 2008

Abstract
Some of the most important aspects to consider during the design, construction and productive life of a well are the amount and nature of the risks associated with the conveyance of downhole instruments to acquire critical formation-evaluation data while the hole is open, and downhole toolstrings needed to monitor or service the well after installing the completion and production hardware.
Wells with horizontal sections in excess of 5,000 ft present significant challenges to the existing well intervention methods and technologies; in particular, production-logging programs under high-production rates using downhole tractor conveyance have proven to be particularly difficult to plan and execute in these wells.
This paper describes the extreme conditions offered by these long horizontal wells, the underlying physics that support modeling of mechanical and hydraulic lift forces, the hazards present when conducting logging operations under flowing conditions using wireline and downhole tractors, the relevant conveyance risk-reduction technologies and methods to successfully plan and execute these extreme operations.
To demonstrate the operational merits and practical aspects of the methods and solutions presented, a case study based on a real operation is included.
Artificial Lift Selection Strategy for the Life of a Gas Well with Some Liquid Production
Authors: Oyewole Peter O. , Lea James F. 
Published: September 2008

Abstract
The Natural Gas industry is often faced with the challenge of selecting an optimal Artificial Lift method for a well in the midst of various artificial lift type choices. These challenges become more complex with increasing dynamic changes in well characteristics over the life of a well. This paper presents a case study on artificial lift selection strategy for unloading liquid from gas well in San Juan basin located in Southwestern, Colorado, and Northwestern, New Mexico. Various modeling techniques were applied to evaluate the lowest bottom hole flowing pressure for various Artificial Lift system types and wellbore geometry. Real life data acquired at the field trials was used to validate model results. The selection strategy resulted in the creation of a robust artificial lift selection matrix and charts for various well configurations as well as production rates for optimum well performance. This approach has a significant impact on gas well production; often loaded up with liquid and prematurely abandoned, due to lack of proper artificial lift strategy. The paper may assist the gas well operator and the need to adequately design, install and operate an optimum artificial lift system for the life of the gas well.
Multiphase Loop Tests for Subsea Separation-Unit Development
Authors: Pagnier P. , Noik C. , Maurel P. , Ricordeau A. , Volle J. L. 
Published: September 2008

Abstract
As flow assurance is a critical point, challenging offshore field development led TOTAL and IFP to manage a large R&D program on multiphase flow behaviour. One of the objectives is to improve the understanding of the behaviour of gas/oil/water mixtures in separation tanks. In the framework of a joint project, a new test facility platform GOwSP (Gas Oil water Separation Platform) was implemented in 2006 on the IFP-Lyon site. The issue consists in improving the design of separator as operators are now faced with more difficult operating conditions related to deep offshore or difficult crudes. The GOwSP is an industrial closed loop test facility designed for R&D program and for testing multiphase equipment such as separators, pumps or flow-meters. The loop includes a large three-phase storage tank (10m3). Gas and liquids are flowing separately towards a mixing point by the way of a compressor and centrifugal pumps. The mixture is sent to the multiphase equipment to be tested before coming back to the storage tank. The loop is completely equipped with basic instrumentation to qualify both the different in/out fluids and the tested equipment: flow meters on each single phase line upstream and downstream from the device, pressure transmitters, temperature sensors, two viscometers and two gamma densimeters. Moreover specific instrumentation is implemented inside the tested separator: two interface probes allow to determine flow hydrodynamic behaviour and phase composition (foam, emulsion). The GOwSP is under pressure and temperature control (Pmax 55bars, T°Cmax80°C). Fluids used are crude oil, salted water and natural gas with flows up to 15m3/h for fluids and 22 Am3/h for gas.
First tests on GOwSP were performed to characterise a vertical gas-liquid separation unit. The tested equipment consisted in a vertical scaled-down separator tank placed downstream two parallel pipes of different diameter and length. Then, tests on a horizontal separator were performed. Preliminary results are presented for several operating conditions of pressure, flow-rates, oil viscosity, mixing-rates and liquid levels.
Broadening the Application Range of Water Shutoff/Conformance Control Microgels: An Investigation of Their Chemical Robustness
Authors: Cozic Céline , Rousseau David , Tabary René 
Published: September 2008

Abstract
The performances of water shutoff and conformance control microgels were extensively investigated in previous works. Microgels are polymeric particles which are preformed, stable, fully water soluble and size controlled with a narrow size distribution. They are also non toxic, satisfying the OSPAR environmental tests. Microgels allow a controlled Permeability Reduction to water through their adsorption as monolayers. When injected in a multilayered reservoir, unlike conventional polymer-based systems, they invade significantly less the low permeability layers, thanks to the low viscosity of their solutions as well as to steric effects. Their penetration in the highest permeability layers is thus largely improved. Microgel technology was successfully applied in 2005 for the treatment of an underground gas storage reservoir: results were very positive in terms of water shutoff and sand control.
However, a broad range of potential applications cases for microgels involve harsh conditions such as high salinity reservoir brines. This paper is principally aimed at studying how high salinity impacts microgel treatment efficiency.
Solubility of microgels was first evaluated in an extended domain of brine salinities (up to 200 g/L NaCl with a high content of calcium). Viscosity measurements and filterability tests through calibrated membrane filters were performed, and led to specifications for optimum microgel dissolution.
Injections in granular pack models were then carried out with microgels diluted in brines of various salinities and at various microgels concentrations. These tests allowed to assess the injectivity and to determine the permeability reductions. After injection, the packs were flushed with different brine salinities. Such a procedure reproduces setting a well back in production after a microgel treatment. Results showed that the hydrodynamic thicknesses of adsorbed layers did not vary significantly when microgels were injected in brines of moderate to high salinities. At very high salinity (200 g/L NaCl with calcium), a shear-controlled over-adsorption of the microgels was observed. Results also showed that adsorbed layers were very stable when exposed, after microgels adsorption, to brines of low to very high salinity.
These positive results are due to the crosslinked structure of the microgels. They highlight once again their excellent chemical stability compared to linear polymer based systems. They bring new encouraging insights for the success of the microgels applications to come.
Observations From a Fieldwide Pressure Data Acquisition Campaign in the Wara Formation of the Greater Burgan Field, Kuwait
Authors: Ambastha Anil , Dashti Qasem , Maizeret Pierre-David , Al-Farhan Farhan , Bou-Mikael Sami , Rajan Sasi 
Published: September 2008

Abstract
The Wara reservoir has been producing for over 60 years and its pressure has slowly decreased over the years, now below saturation pressure in some structurally-high areas where gas cap has increased in size compared to very small initial gas caps in these areas. A peripheral, water injection project is being considered to maintain the pressure above bubble point and improve oil recovery from the flank areas. However, limited information is available concerning Wara reservoir heterogeneity. Shut-in of all Wara producers provided an "once-in-a-lifetime" opportunity to carry out a fieldwide pressure data acquisition campaign. Over a period of six months (Nov. 2006-May 2007), 127 static bottom-hole pressure (SBHP) surveys, 26 pressure buildup (PBU) tests (including buildup tests for 2 active wells of the interference test program) and 3 interference tests were conducted. Each interference test involved one active well and 3-6 observation wells. This paper describes a systematic methodology to select wells to test on a fieldwide basis, test design exercise, data acquisition program execution, and observations and conclusions reached from this data set.
Over the duration of the campaign, an increasing pressure trend was observed in almost all wells slated for PBU and interference tests. This observation was made possible due to multiple SBHP recordings in these wells. The linearly-increasing pressure trend had to be taken into account in the analyses of the buildup tests to avoid interpreting wrong boundary conditions. Wellbore dynamics also initially affected some pressure buildup tests and were later circumvented by the use of a downhole shut-in tool (DHST) to limit the phase segregation effect. The transient analyses revealed different flow regimes, from infinite-acting radial flow, to dual-layer and radial composite with or without sealing faults. From the SBHP data, maps have been made to assist in identifying compartments. One interference test showed anisotropy which could be critical in the implementation of a water injection project. Overall, the interpretation of the data from this extensive data acquisition campaign has shed light on reservoir heterogeneities that have been integrated with changes made in a full-field, "Wara only", history-matched simulation model.
Development and Use of High Density Fracturing Fluid in Deep Water Gulf of Mexico Frac and Packs
Authors: Rivas L. , Navaira G. , Bourgeois B. , Waltman B. , Lord P. , Goosen T. 
Published: September 2008

AbstractIn the Gulf of Mexico, there has been an increase in the number of wells drilled to depths greater than 20,000 ft with bottomhole pressures exceeding 20,000 psi. These deeper wells present drilling and completion challenges to the industry. Two of these challenges include fracture stimulation for low permeability and frac and pack sand control for higher permeability. Because of the high fracture gradient and friction in the wellbore tubulars, a conventional 1.0 to 1.04 SG fracturing fluid would require surface treating pressures greater than 15,000 psi. In the offshore marine environment, 15,000 psi pressure is the current limit of the flexible treatment line that transmits fluid from the stimulation equipment on the marine vessel to the wellhead on the rig.To solve this limitation, a borate-crosslinked high-density fracturing (HDF) fluid with of up to 1.38 was developed to harnesses the power of gravity and reduce the amount of surface treating pressure required to achieve adequate bottomhole fracturing pressure without exceeding the safety limits of the surface equipment. In numerous wells, a minimum of 20% reduction in surface treating pressure over the conventional 1.04 SG was recorded.This paper summarizes the well conditions, extensive fluid qualification testing, procedures, and selected job results along with final completion performance indicators.The HDF fluid enables treatment of these deep offshore wells by lowering surface treating pressure. Conventional 15,000 psi equipment could be used, less horsepower was required, and creating a safer work environment was achieved.
Relative Permeabilities for Blowdown of a Near-Critical Oil Reservoir: Issues and Solutions Emerging From Pore-Scale Network Modelling
Authors: Bondino I. , Ezeuko C. C. , McDougall S. R. , Ward R. , Hamon G. 
Published: September 2008

Abstract
This work constitutes a practical attempt at addressing issues surrounding depletion gas-oil relative permeabilities in the case of a near-critical oil by using pore-scale network modelling techniques. Firstly a new model for gas buoyancy is presented that is able to track dynamically the movement of buoyant gas in the pore network; this framework is successfully used to model experimental visual observations of "coherent" channelized gas flow and dispersed "incoherent" gas flow that are seen to take place in porous media as permeability increases. We then apply the pore-scale network model to study the dynamics of gas flow during reservoir depressurization in virgin and waterflooded conditions with the dual purpose of understanding the microscopic flow behavior and producing predicted estimates for the variation of multi-phase flow properties: this is undertaken at two PVT extremes (fluid samples separated by a depth interval of 200m, from the top and bottom of the oil bearing column), and for two extremes of rock permeability (5mD and 252mD).
It is found that the very low gas-oil interfacial tension at the onset of the pressure decline induces strong gas buoyancy effects, even at the pore scale. Moreover, the variation in PVT properties along the oil bearing column, coupled to permeability differences, causes a transition of behaviours in the reservoir: from vertical gravity-driven gas flow in virgin systems, to more capillary-controlled, isotropic gas patterns under conditions of lower permeability, heavier oil, and/or high water saturation. In particular, under strong buoyancy conditions, anisotropy in gas flow during depletion is seen to be time dependent, with vertical gas flow at low gas saturations dominating the process initially. The gradual formation of a gas cap, however, slowly increases the extent of horizontal flow near the top of the system. In light of these observations, the issue of flow anisotropy and its impact on gas-oil relative permeability is examined in some detail by computing network fluxes in both the horizontal and vertical (along-gravity) directions.
Study of the PVT Properties of Gas—Synthetic Drilling Fluid Mixtures Applied to Well Control
Authors: Monteiro E. N. , Ribeiro P. R. , Lomba R. F. T. 
Published: September 2008

Abstract
The study of the interaction between the formation gas and the drilling fluid during offshore operations as well as in HPHT environment is essential to safely and economically drill the pay zone of the well. The environmental regulatory issues and the peculiar technical aspects involved in deep and ultradeep waters require low toxicity synthetic drilling fluids. The main objective of this study was to understand the PVT behavior of those fluids by the experimental determination and modeling of thermodynamic properties such as: solubility, specific gravity and formation volume factor of the fluid. Those properties have a direct impact on kick detection and circulation out of the well and should be addressed in well control planning and execution. The experimental work was conducted in a PVT lab, using mixtures of methane and n paraffin based emulsions as unweighted drilling fluids, tested at the temperatures of 158, 194 and 302o F. The pressure, temperature and fluid composition effects on those gas-liquid properties were analyzed and the experimental data for solubility and formation volume factor compared to predictions considering the additivity hypothesis and mathematical fittings based on the experimental data. A model for the methane and n paraffin system based on literature data and Peng-Robinson equation of state has also been fitted to the data in order to discuss the application of the additivity hypothesis for the emulsions. Pit gain evaluation based on the correlated experimental data for the synthetic drilling fluid has been performed and compared to the values expected for water based muds.
Glass Reinforced Epoxy Casing: Lessons Learned After Cementing and Completion of 70 Wells
Authors: Romera G. , Robles J. , Peacock H. , Morris W. , Peralta D. 
Published: September 2008

Abstract
The use of Glass Reinforced Epoxy (GRE) casing has increased significantly during the last decade, primarily on secondary recovery water injector wells. Corrosion resistance is this material main advantage when compared to steel. Almost one hundred wells have been completed in the Neuquén basin, Argentina, during the past five years.
This paper presents the experience obtained after cementing and completion of 70 GRE cased wells. Improvements on cement slurry mix designs, mud cleaning preflushes systems and best practices to ensure successful stimulation conditions (acids and fractures) are provided.
The work is supported by a laboratory study focused on the GRE casing to cement bonding performance evaluation and a finite element numerical simulation analysis of the down-hole service conditions achieved during stimulation jobs. This study considered the influence of GRE, cement and rock mechanical properties, the mud-cake removal conditions, as well as different bonding conditions. A comparison between GRE and steel cased wells is presented.
Cementing results were improved by casing centralization, increasing the preflushes aggressiveness and using low density slurries. Bonding experimental results showed that original GRE external coating attempts against cement bonding strength.
The numerical simulations show that when GRE casings are subjected to high internal pressures, its elastic behavior (Young modulus ten times lower than steel) generates overloading on the cement annulus. This condition could generate cracks that will propagate along the annulus creating communications paths between close perforated zones during stimulations treatments. This situation is even worst when poor formation mud-cake removal takes place.
The Impact of Effective Fracture Area and Conductivity on Fracture Deliverability and Stimulation Value
Authors: Brannon Harold D. , Starks Thomas R 
Published: September 2008

AbstractThe economic success of stimulated wells may be defined by the Return on Fracturing Investment (ROFI): the well performance relative to the cost of the hydraulic fracture stimulation employed. Hydraulic fracture deliverability is largely defined by the effective fracture area, which is that portion of the created fracture area exhibiting sufficient conductivity contrast within the productive reservoir interval. Previous studies demonstrating that stimulated well performance can be improved by increasing fracture conductivity have generally addressed characteristics of the proppant pack: optimized proppant properties, increased proppant size, increased proppant volume, and minimized damage to the created fracture permeability. Improving overall fracture area has typically been addressed by employing larger treatments and proppant volumes. Thus, previous approaches to enhancing fracture deliverability have resulted in increased stimulation cost, which, unless accompanied by a similar scale of increase in well productivity, has negative implications on ROFI.The decades-old theory of increasing fracture deliverability by placing proppant in partial monolayers (PMLs) rather than multi-layer packs was resurrected in 2004 with the introduction of ultra-lightweight (ULW) proppant. The theory states that a partial monolayer exhibits conductivity equivalent to 15 to 20 layers of proppant in a packed fracture, which equates to a difference in areal proppant concentration of greater than 20X. In addition to enabling placement in a partial monolayer, the transportability of ULW proppant has been shown to provide greatly increased effective fracture area. Case histories of PML fracturing treatments have consistently illustrated stimulated production increases well beyond expectations, effectively validating the productivity benefits of the process.The focus of this paper is to characterize the ROFI implications of PML designs using ultra-lightweight proppants in comparison to typical packed fracture designs using conventional proppants. Advanced fracture modeling will be used to illustrate the effects of fracture conductivity (proppant type, concentration, & damage) and effective fracture area on well performance. Normalized stimulation costs of the respective designs will be assessed against the resultant fracture deliverability and projected ROFIs.
Survivability of Optical Fiber for Harsh Environments
Authors: Ramos R. T. , Hawthorne W. D. 
Published: September 2008

Abstract
Today, optical-fiber systems are used in the oilfield for sensing and telemetry applications. The most commonly used downhole is the distributed temperature sensing (DTS) system which collects permanent real-time temperature well logs. These logs are extremely useful for real-time production allocation, heavy oil thermal recovery (e.g., steam-assisted gravity drainage, SAGD), steam-well management, and well-integrity monitoring.
Unfortunately, optical fibers are not immune to degradation under downhole conditions. Hydrogen, present in the wells because of corrosion or other factors, can attack the optical-fiber components causing attenuation increase. This attenuation can have a negative effect on the performance of the system, such as decreasing accuracy or resolution. Understanding the process and the impact of this degradation is of great importance to the reliable operation of these optical-fiber systems.
This article shows how a combination of controlled testing and modeling calculations can be used to provide an estimation of the attenuation increase expected from the fiber with time and downhole conditions.
Test results for attenuation of optical fiber in hydrogen atmospheres and under downhole temperatures will be shown. The article also provides results from the testing of a new optical fiber that was designed to give a considerable improvement in resistance to hydrogen attack. These results give an order of magnitude improvement in comparison with commercially available optical fibers. Early field tests are consistent with the results of the study.