bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Alternative Solution to Sandstone Acidizing Using a Nonacid-Based Fluid System with Fines-Migration Control
Authors: Rozo Rafael , Paez Javier , Mendoza Alberto , Milne Arthur , Soler Diego , Abuseif Hussam 
Published: December 2007

Abstract
The Caballos formation is thick laminated sandstone with less than 10% of total clays and permeability ranging from 20 mD to as high as one Darcy. However, the production from this formation is often limited due to the low critical flow rate in the matrix (less than 1 mL/min) and associated fines migration as shown in several tests.
Historically matrix acidizing and hydraulic fracturing treatments in this formation have only been partially successful due to destabilization of the clays and inadequate fines stabilization, along with the incompatibility of the crude oil with many conventional acid systems.
In order to overcome the limitations associated with the use of conventional acid systems an extensive laboratory study was conducted using a non-acid based stimulation fluid. The base fluid selected was a newly developed chelating agent that is very tolerant to high concentrations of both carbonate and aluminosilicates, and iron and zeolite bearing minerals. By including acid salts in the fluid it proved possible to develop a fluid system with the equivalent dissolving power of a conventional 6:1.5 (HCl: HF) mud acid, even at temperatures as low as 180°F. Testing also showed that the fluid was capable of controlling fines migration and that a scale inhibitor could be included in the formulation, while the fluid system exhibited excellent compatibility with the formation fluids throughout the field.
The newly developed non-acid fluid system provides some unique advantages for matrix acidizing applications and in particular for stimulating the Caballos formation 1) Minimizes the risk of secondary and tertiary precipitation due to the nature of the chelating agent 2) A single treating fluid instead of the multiple fluids/stages used in a conventional treatment 3) Greatly reduced sludging and emulsion tendencies compared to conventional acid systems (without the addition of surfactants or demulsifiers) and much lower corrosion rates 4) The ability to stabilize fines present in the matrix 5) Allows for a scale inhibitor to be included in the treating fluid 6) Reduces the logistics and HSE risks during the execution of the treatment.
This paper reviews the laboratory testing including an extensive core flow testing performed to develop a new nonacid treating fluid for both matrix acidizing and dual stimulation applications in the Caballos formation and its implementation in the field, illustrated with case studies and production data.
Matching of Production History and 4D Seismic Data—Application to the Girassol Field, Offshore Angola
Authors: Roggero F. , Ding D. Y. , Berthet P. , Lerat O. , Cap J. , Schreiber P. E. 
Published: December 2007

Abstract
This paper presents an advanced history matching methodology for constraining 3D stochastic reservoir models to both production history and 4D seismic attributes. The proposed approach is based on an optimization loop which integrates geostatistical modeling, upscaling, fluid flow simulation and petro-elastic modeling in the same workflow. Simulated production history and 4D seismic attributes are compared to real data using a single objective function, which is minimized using a new optimization algorithm based on response surface fitting.
Inversion parameters can be selected throughout the entire modeling workflow, to update the facies spatial distribution, the petrophysical properties and fluid flow parameters. Advanced parameterization techniques are used to constrain the fine scale geostatistical model. The gradual deformation method allows smooth transformations of the facies model realization while conserving the overall statistical characteristics. In addition, a new history matching technique has been implemented to constrain the average facies proportions over given regions. As an example, new geologically-based parameters like shale proportions in flow barriers or sand proportions in channel sequences can be considered in the inversion process.
A successful application to the Girassol field is presented. Girassol is a large, complex and faulted turbidite field located offshore Angola. A detailed geostatistical model was built first from 3D high resolution seismic data. The major challenge was to integrate 4D seismic data to constrain the reservoir model in a quantitative way.
The gradual deformation method has shown a major impact on production history, since the changes in the facies distribution affect the connectivity in sandy channels and the position of shaly barriers. A good match of water and gas breakthrough was obtained over one year of production data. The addition of new geological constraints allowed us to better honor the 4D seismic information (extent of gas injection and of depleted zones). This was achieved by constraining average sand and shale proportions over channel and levee regions. Improved predictions of future production and of a new seismic survey have been obtained using the matched model.
An LWD Tool Suite for Formation Evaluation in HP/HT Environments
Authors: Rennie A. , Boonen P. 
Published: December 2007

Abstract
The tool suite that is introduced in this paper provides Logging-While-Drilling (LWD) formation evaluation with tools rated up to 350°F (175°C) and 25,000 psi (172.4 MPa). These ratings qualify as High Pressure High Temperature (HPHT) environments for LWD services, where the standard ratings are much lower. The HPHT LWD suite consists of measurement-while-drilling (MWD), annular pressure, resistivity and nuclear porosity services.
The MWD service provides surveys, optional gamma ray measurements and the mud-pulse telemetry connectivity to the surface. Changes to the real-time pulsed telemetry data streams can be requested from the MWD surface system to accommodate customer requirements for any sections logged within the wellbore. A retrievable MWD system is also available for high-risk drilling environments and conditions. The quartz pressure tool measures annular pressure, drill pipe pressure and mud temperature.
The resistivity service comprises of a dual frequency (2MHz and 500 kHz) borehole compensated wave propagation tool with three transmitter-to-receiver coil spacings. The combination of dual frequency, triple transmitter coils and phase/attenuation measurements provides twelve resistivity curves with different diameters of investigation. Advanced resistivity analysis compute six dielectric assumption independent resistivities, and the related dielectric constants. In anisotropic formations in high angle wells, the horizontal and vertical resistivities are calculated.
The porosity service is a density-neutron-stand-off-caliper tool. The spectral bulk density (Rhob) measurement is compensated for stand-off. Three neutron porosities are computed from the three neutron detectors. The more environmentally friendly Californium252 source emits a neutron output comparable with a conventional LWD Americium-Beryllium source but at a much lower radioactivity. The source is recyclable, thus removing the need for quasi-eternal storage for depleted sources.
The tools in this suite are modular and can be configured in any order. A selection of Bottom Hole Assemblies (BHA) will be shown. Examples will show the range of measurements and the advanced applications.
Real-Time Fiber-Optic Casing Imager
Authors: Appel M. , Dria D. , Freeman J. , Rambow F. , Shuck M. , Childers B. , Poland S. , Dominique T. 
Published: December 2007

Abstract
During the last years, significant progress has been made in the use of fiber-optic technology for well and reservoir surveillance purposes. While most effort in this field appears to be concentrated on the development of fiber-optic based temperature-, pressure- and flow meters, comparably few publications have been made to-date about the use of fiberoptic technology for monitoring deformations of well tubulars and casings.
In this article we report on recent advances in our development of a real-time fiber-optic based casing imager. This device is designed for continuous, high-resolution monitoring of the shape of casings or well tubulars and, therefore, enables the determination of strain imposed on the well. Small-scale and full-casing-size laboratory tests have demonstrated that the latest generation of this system is sufficiently sensitive to detect casing deformations of less than 10 degrees per hundred feet and covers compressive and tensile axial strain ranges from less than 0.1% to 10%. We will discuss the background technology, the measurement sensitivity and strain-response characterization, as well as the scale-up work that has been performed to-date. Our article also includes an overview of field test results and illustrates how real-time deformation monitoring could form a significant component of reservoir surveillance strategies.
Effect of Internal Baffles on Volumetric Utilization of an FWKO—A CFD Evaluation
Authors: Lu Yaojun , Lee Joseph M. , Phelps Daniel , Chase Ryan 
Published: December 2007

Abstract
This paper presents the results of a CFD evaluation on the effectiveness of perforated plate baffles for improving flow and separation performance in a FWKO separator. Using the multiphase model coupled with turbulent interaction, a full scale 3D simulation on two FWKO configurations indicated that with installation of the perforated plate baffles, the short circuiting and recirculation flow in the vessel was reduced. As a result, the mean residence time increased from 630 seconds to 980 seconds for the water phase, and from 520 seconds to 745 seconds for the bitumen phase. Accordingly, the volumetric utilization for the bitumen phase was increased from 46% without the baffles to 66% with the baffles, which corresponds to a 43% improvement. Water phase volumetric utilization was increased from 57% without the baffles to 89% with the baffles, which was increased by 55%. Therefore, an overall 50% improvement on the liquid phase was achieved due to the introduction of the specially engineered perforated plate baffles.
Fluid Density and Viscosity Effects on Borehole Resistivity Measurements Acquired in the Presence of Oil-Based Mud and Emulsified Surfactants
Authors: Salazar Jesus M. , Malik Mayank , Torres-Verdín Carlos , Wang Gong Li , Duan Hongyan 
Published: December 2007

Abstract
We quantify the influence of oil-base mud-filtrate invasion and formation fluid properties on the spatial distribution of fluid saturation and electrical resistivity in the near-wellbore region. The objective is to appraise the sensitivity of borehole resistivity measurements to the spatial distribution of fluid saturation resulting from the compositional mixing of oil-base mud (OBM) and in-situ hydrocarbons.
First, we consider a simple two-component formulation for the oil phase (OBM and reservoir oil) wherein the components are first-contact miscible. A second approach consists of adding water and surfactant to a multi-component OBM invading a formation saturated with multiple hydrocarbon components. Simulations also include presence of irreducible, capillary-bound, and movable water. The dynamic process of OBM invasion causes component concentrations to vary with space and time. In addition, the relative mobility of the oil phase varies during the process of invasion because oil viscosity and oil density are both dependent on component concentrations.
Presence of surfactants in the OBM is simulated with a commercial adaptive-implicit compositional formulation that models the flow of three-phase multi-component fluids in porous media. Simulations of the process of OBM invasion yield two-dimensional spatial distributions of water and oil saturation that are transformed into spatial distributions of electrical resistivity. Subsequently, we simulate the corresponding array-induction measurements assuming axial-symmetric variations of electrical resistivity.
We perform sensitivity analyses on field measurements acquired in a well that penetrates a clastic formation and that includes different values of density and viscosity for mud-filtrate and formation hydrocarbon. These analyses provide evidence of the presence of a high-resistivity region near the borehole wall followed by a low-resistivity annulus close to the non-invaded resistivity region. Such an abnormal annulus is predominantly due to high viscosity contrasts between mud-filtrate and formation oil. The combined simulation of invasion and array-induction logs in the presence of OBM invasion provides a more reliable estimate of water saturation, which, in turn, improves the assessment of in-place hydrocarbon reserves.
Applied Technology Helps Revitalize a Maturing Giant Gas Field: Learnings From the Cleveland Formation's Horizontal-Well Redevelopment Program
Authors: Decker Neil C. , Bumbaugh David B. , Brogdon Ron L. , Gardner David C. , Roberts Stephen P. , Petersen Sean D. 
Published: December 2007

Abstract
The Cleveland formation is a giant tight gas reservoir present across a large area of the northeastern Texas Panhandle and western Oklahoma. The full development potential of the Cleveland has historically been inhibited by variable well performance, inefficient reservoir drainage, and marginal economics. To help address these challenges, operator strategies have shifted in recent years to infill drilling with horizontal wells. This has introduced challenges such as optimizing horizontal well orientation, lateral length, completion type, and the number and length of hydraulic fractures, all within the context of a partially depleted reservoir. To help determine the optimal horizontal well configuration and completion type, operators have become active in acquiring data to improve their understanding of the reservoir and to quantify the variables driving well performance.
Data acquisition includes extensive subsurface mapping, core analysis, well bore stability analysis, open-hole logging, micro seismic acquisition during fracture stimulations, injection-fall-off tests (IFOT), and production decline analysis. Analysis of this data has led to updated material balance calculations and reservoir simulation models, a shift in completion technology, and better quantification of the distribution of the remaining hydrocarbon resource.
Micro seismic data has influenced the selection of a prefered completion design and, along with geomechanical modeling, has improved understanding of fracture behavior and orientation. Similarly, field data has provided indications of generally lower effective gas permeability. In addition, evidence of natural fractures has necessitated their consideration in stimulation design.
Reservoir pressures (inferred from IFOT results), completion data, and reservoir simulation modeling, are helping to guide optimal well placement and completion type of horizontal wells. To further address the economics of drilling horizontal wells, a novel coiled-tubing drilling (CTD) program for reentry into existing vertical wells has been piloted with encouraging initial production results.
In order to more economically exploit this giant field, technological collaboration between operators, who have individually evolved important expertise, has become increasingly important. The integration of data acquisition, application of technology, and collaborative sharing of best practices has resulted in confidence for the re-vitalization of this giant North American gas reservoir.
Successful Applications of Azimuthal Propagation Resistivity for Optimum Well Placement and Reservoir Characterization While Drilling
Authors: Chemali Roland , Hart Eric , Flynn Tracey , Meyer Hal , Helgesen Tron , Kirkwood Andrew , Merchant Abbas , Berle Alf Erik 
Published: December 2007

Abstract
We illustrate the use of a new technology for navigating and characterizing various types of oil reservoirs. Real-time images from Azimuthal Propagation Resistivity measurements provide a "map" of the resistivity patterns up to several meters around the wellbore. In addition, recently developed processing and quantitative interpretation techniques help guide the placement of the well and provide a new perspective of the formation.
When navigating in gas drive reservoirs, the azimuthal resistivity measurement is used to maintain the wellbore at a prescribed distance above the oil-water contact. With its exponential sensitivity to distance, the measurement is able to detect even small changes in the distance to the oil-water interface. In a few instances, the azimuthal information provided by the real-time deep resistivity images indicates probable coning due to offset well production.
Similar principles are applied in high angle drilling of water drive reservoirs. The deep azimuthal information allows the drilling engineer to maintain the wellbore at a prescribed distance immediately below a shale roof. The deep resistivity image from the azimuthal resistivity measurement also makes it easy to distinguish the roof from the occasional approaching shale lens.
Whereas shallower reading LWD image logs (e.g. Gamma Ray and Density) only indicate a geological feature proximal to wellbore, the deep reading azimuthal resistivity measurement can provide geologic structure information at the reservoir scale. Visual displays show the subsurface surrounding the wellbore; quantitative algorithms accurately compute the distance, direction, and apparent dip for reservoir related geological events. A new conductivity unit named "Transverse Siemens" is proposed to help quantify the new azimuthal propagation measurement.
Improving LWD Image and Formation Evaluation by Utilizing Dynamically Corrected Drilling-Derived LWD Depth and Continuous Inclination and Azimuth Measurements
Authors: Bordakov G. A. , Kostin A. V. , Rasmus J. , Heliot D. , Laastad H. , Stockhausen E. J. 
Published: December 2007

Abstract
The paper illustrates the improvements in logging while drilling (LWD) images and subsequent formation evaluation by utilizing a new methodology for depth and survey measurements correction.
LWD depth measurements are often considered inaccurate and therefore not as reliable for well-to-well correlations, correlations to offset data acquired with wireline measurements and formation layer thickness determinations. The reasons for these inaccuracies generally originate from the traditional practice that LWD depth is purposely made equal to the driller's depth, which is a static pipe length measurement made by tape at surface.
There is almost always a difference between the actual measured depth (MD) of the LWD sensor downhole and this static pipe measurement because downhole, the drillpipe is subject to an environment that is not representative of the derrick, such as, varying drilling mechanical conditions and temperature changes. We demonstrate the applications of the method, which allows dynamic driller's depth correction for the effects of drillstring weight, downhole friction, weight on bit, thermal expansion, residual rig heave, and tide.
Another significant inaccuracy source is a standard practice of calculating borehole position from stationary survey points typically taken every 90 ft using minimum curvature method. Neglecting complex borehole shape between survey stations leads to a systematic error in determining the borehole position. We consider using continuous inclination and azimuth measurements along with stationary surveys to correct these errors.
We provide comparisons of LWD images before and after the depth and survey corrections to illustrate how the measurement errors affect formation dips interpreted from the images. We demonstrate how improved accuracy allows filtering out the artifacts together with more decisive and accurate identification of geologic features. We show how using the corrected 3D position allows to improve accuracy of formation thicknesses calculations and therefore to improve reservoir summation results.
As a result we propose a borehole 3D position measurement that is accurate, consistent between wells regardless of rig type or bottomhole assembly (BHA) configuration, and independent of drilling mode. Using this new measurement significantly improves the quality of formation evaluation.
A Comparative Study of Capillary-Pressure-Based Empirical Models for Estimating Absolute Permeability in Tight Gas Sands
Authors: Comisky J. T. , Newsham K. E. , Rushing J. A. , Blasingame T. A. 
Published: December 2007

Abstract
This paper presents the results of a laboratory study where we compare permeability estimates obtained from several mercury-injection capillary-pressure-based models to a set of measured (steady-state), Klinkenberg1-corrected permeability in tight gas sands. We evaluated 63 core samples from several prolific tight gas reservoirs in the U.S. Steady-state permeability and mercury-injection capillary pressure tests were completed on each sample.
The permeability samples range is from 0.0001 mD to 0.2 mD. We review a variety of currently-employed models that are classified as belonging to either Poiseuille or Percolation/ Characteristic Length models. We identify those correlations that are best applied in tight gas sands by quantifying each method's accuracy and precision and force rank each based on error analysis score.
Managing Dual Careers While Working in the Oil and Gas Industry: A Critical Element in Attracting and Retaining Talent
Authors: Chadud N. , Tealdi L. , Howes S. , Sprunt E. 
Published: December 2007

Abstract
Dual career couples are becoming increasingly common in the oil and gas industry. Due to the increasingly frequent demand for mobility, employees are being required to make significant career decisions earlier and earlier in their careers that affect the life and career of their partners. The barriers to achieving a successful career, while simultaneously maintaining a happy relationship with a partner with their own career, are rarely recognized or discussed. Recent worldwide surveys carried out within the Exploration and Production sector demonstrate that work-life balance is becoming an increasingly important consideration in job selection and career decisions. In many countries, private life management ranks high in the pyramid of personal needs. This should not be neglected and significant actions should be taken promptly to overcome the potential for talent loss through migration to other industries and companies. Supporting work-life balance is a critical element in ensuring long-term sustainability of the energy professional workforce. Analysis of surveys of both young and more experienced oil and gas industry professionals is used to recommend actions to avoid the talent loss caused by the difficulties of balancing dual careers and private life with job mobility requirements.