bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reservoir Property Implications of Pore Geometry Modification Accompanying Sand Diagenesis: Anahuac Formation, Louisiana
Authors: Holland Michael T. 
Published: December 2007

ABSTRACT
This paper represents a study of reservoir pore modification accompanying diagenetic secondary porosity development within a deep (13,400') overpressured Anahuac Formation sandstone in southern Louisiana. Such secondary porosity formed by dissolution of carbonate cement, detri-tal grains, and other soluble replacive minerals comprises a significant portion of porosity formed in U.S. Gulf Coast Tertiary reservoir sands. The primary pore system within this reservoir was significantly enlarged (up to 35% porosity) by selective dissolution of soluble material by acidic fluids generated during hydrocarbon maturation and shale dewatering. Subsurface secondary porosity development is significant in influencing: 1) the type, amount and rate of fluid to be produced, 2) the development of potential reservoir porosity after primary porosity has been destroyed by compaction, and 3) mechanical competence of the reservoir to compaction accompanying production.
Using scanning electron microscopy, petrographic examination, mercury injection and core testing at in-situ reservoir conditions, characteristics of the reservoir pore system were examined from core within this particular sand interval. Secondary pore size and distribution was found to be affected by: 1) sandstone mineralogy, 2) pore matrix content, and 3) sedimentary structures and resulting textural components hindering fluid flow.
Mechanical competence of secondary porosity to compaction in sandstone reservoirs is an important parameter when considering reservoir stress sensitivity. Keystone bridging relationships between grains and silica overgrowths can be established during the initial phases of compaction such that when leaching of cement and soluble grains occurs, the less soluble quartz grain matrix is supportive to porosity development. Special core tests were performed at simulated in-situ reservoir conditions of pressure and temperature to examine porosity and permeability reduction as a function of effective stress generated by reducing pore pressure (simulated fluid production). Observed mechanical resistance to uniaxial compaction at reservoir conditions was determined within portions of the sand containing high (~30%) secondary porosity. Volumetric strain measured during testing showed less than 2% reduction in total core volume accompanying a 6000 psi reduction in pore pressure. However, permeabilities were reduced by 26-89%. These data reflect how pore apertures connecting pores were affected by compaction.
Fracture Detection Techniques in the Georgetown and Austin Chalk Formations
Authors: Julian Preston J. 
Published: December 2007

ABSTRACT
This study relates the success of detecting and analyzing naturally fractured systems in the Austin Chalk and Georgetown Formations from log evaluations. The Austin Chalk is composed principally of calcareous unicellular algal remains called cocospheres and their disunited, gear-shaped, skeletal remains called cocoliths. The Georgetown Formation is a hard, dense, and finely brittle limestone. Both formations contain matrix porosity, but are dependent on open fracture systems for economical hydrocarbon production. Hence, defining and evaluating the developed fracture systems before setting an expensive casing string is important. The Dual Induction Log and the Compensated Neutron-Formation Density Log offers an economical method of evaluating these fracture systems.
Case studies in Robertson, Milam, and Burleson Counties, Texas have shown that fracture systems near the wellbore can be detected. Attempts to determine the existence of hydrocarbons in fracture systems using logs were successful in the Austin Chalk and Georgetown Formations. Full core analyses were also successful in determining the existence of these fracture systems. However, obtaining core samples on all wells as a method of determining fracture systems is not recommended due to the high cost of coring.
Emphasis of this study is on the use of logs to determine the existence of economically recoverable hydrocarbons in fracture systems. Although this study concludes that logs were successful in detecting naturally fracture systems near the wellbore, they cannot predict the effects of mechanical fracturing on the formation. Hence geological trends in the area must also be considered.
Development of a Kinetic Model for In-Situ Combustion and Prediction of the Process Variables using TGA/DSC Techniques
Authors: Vossoughi Shapour , Barlett Gordon W. , Willhite G. Paul 
Published: December 2007

ABSTRACT
This paper describes the development of a kinetic model of the in-situ combustion process from data obtained from Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). The kinetic model was used to predict fuel deposition and combustion rate in a combustion tube. Good agreement was obtained between predicted and observed fuel deposition and combustion rate in two combustion tube runs.
A crude oil from Iola County, Kansas, was studied. This oil has a gravity of 19.8° API and a viscosity of 222 cp at 38°C and 89 cp at 54°C. Data from TGA experiments on Iola crude heated in the presence of air were obtained. Analysis of combustion gases from the TGA was done by gas chromatography to determine the nature of the reactions occurring during the TGA runs. Main reactions/transitions identified were distillation, low temperature oxidation, cracking and combustion.
A kinetic model of the TGA process was developed from thermograms. The model is based on the weight of crude oil components which undergo main reactions/transitions. The kinetic model was used to predict the percentage of the crude oil deposited as fuel in the combustion process as well as the time for consumption of the fuel within the combustion zone. By estimating the length of the combustion zone from an energy balance across the region where combustion reactions take place in a combustion tube, it was possible to predict the rate at which fuel was consumed during the process.
A combustion tube run was made with silica sand containing 8.0% by weight Iola crude oil in order to test the prediction by the kinetic model derived from thermal analysis techniques. Results of the combustion tube run were in good agreement with predicted values of this work and another run from the literature which was performed on the same crude oil.
The fuel heating value and heat availability during the process were also estimated by DSC techniques. However, the estimated heating values were low. This was attributed to the Increase in heating value of the crude oil in the combustion tube due to low temperature oxidation and distillation effects downstream of the combustion front.
Application of Linear and Spherical Flow Analysis Techniques to Field Problems—Case Studies
Authors: Kohlhaas Charles A. , del Giudice Claudio , Abbott William A. 
Published: December 2007

ABSTRACT
Most engineers examine well-test data only with techniques developed for flow in a horizontal cylindrical-radial pattern toward the wellbore. Spherical and linear flow have application in many reservoir situations. Spherical flow has been examined extensively by many authors as an intermediate period between two radial-flow periods for wells which have a short completion interval in thick formations. Linear flow situations develop early in the life of wells which have been fracture-treated: their early linear-flow periods are followed by radial flow. Linear flow may develop late in a well test after a period of early radial flow due to certain configurations of reservoir geometry.
Techniques for analyzing spherical and linear flow are summarized here. Data plots which should be prepared and diagnostic features for recognizing and. interpreting spherical and linear flow are outlined. These techniques are applied to three example cases to illustrate the methods of analysis and the types of information which can be developed from such analyses and cannot be obtained from the standard Horner-plot analysis.
Uncertainties About Future World Oil Prices
Authors: Kilgore W. Calvin , Sandoval A. David 
Published: December 2007

ABSTRACT
Projections of world oil prices are made with the knowledge that circumstances surrounding the world market can change abruptly, often as the result of political considerations. The ability to produce oil and the overall demand for oil change less rapidly. Anticipated world developments in these areas suggest that prices, adjusted for inflation, could easily remain flat through 1985 and then rise steadily during the next 10 years, doubling by 1995.
Non-Darcy Compressible Flow of Real Gases in Propped Fracture
Authors: Ubani Ephraim A. , Evans Ronald D. 
Published: December 2007

ABSTRACT
The development of a simple hyraulically fractured gas well model is presented. A one-dimensional fracture flow model is used to investigate the effects of non-Darcy flow of a real gas in a hydraulically induced, vertical, propped fracture. A sensitivity analysis was performed on the inertial resistance factor β, to determine how any variation in the value of β would affect performance predictions based on non-Darcy flow. It was observed that non-Darcy flow effects in the fracture may be significant especially at the vicinity of the wellbore. It was also noted that the accuracy of non-Darcy flow predictions is quite sensitive to the interial resistance factor. Test results of the model are presented.
Practical Applications for a Gas Well Model With a Fracture
Authors: Poundstone David J. , Crafton James W. , Brown Charles A. 
Published: December 2007

ABSTRACT
Production and reservoir problems can be routinely evaluated from pressure-production history using an efficient model of an individual gas well with a fracture. The model can be used to predict long term performance and make ultimate reserve determinations. Predictions can be used to compare against actual performance to isolate reservoir and mechanical problems such as critical flow restrictions, water loading, sand fillup, or permeability degradation. The model's ability to handle vertical fractures enables evaluation and design of effective field-wide fracture treatments. Because it can develop realistic gas deliverability scenarios, it can be applied to production facilities design and field exploitation. These applications are addressed with case study examples.
Seeking Prospects for Enhanced Gas Recovery
Authors: Doherty Mark G. , Randolph Philip L. 
Published: December 2007

ABSTRACT
As part of the Institute of Gas Technology's (IGT) ongoing research on unconventional natural gas sources, a methodology to locate gas wells that had watered-out under over-pressured conditions was developed and implemented. Each year several trillion cubic feet (Tcf) of gas are produced from reservoirs that are basically geopressured aquifers with large gas caps. As the gas is produced, the gas-water interface moves upward in the sandstone body trapping a portion of gas at the producing reservoir pressure. The methodology for identifying such formations consisted of a computer search of a large data base using a series of screening criteria to select or reject wells. The screening criteria consisted of depth cutoff, minimum production volume, minimum pressure gradient, and minimum water production. Wells chosen by the computer search were further screened manually to seek out those wells that exhibited rapid and large increases in water production with an associated quick decline in gas production indicating possible imbibition trapping of gas in the reservoir.
The search was performed in an attempt to characterize the watered-out geopressured gas cap resource. Over 475 wells in the Gulf Coast area of Louisiana and Texas were identified as possible candidates representing an estimated potential of up to about 1 Tcf (2.83 × 1010 m3) of gas production through enhanced recovery operations. In addition, several thousand wells appeared to have watered-out but not at high enough pressures or with what was considered a strong enough water drive. Furthermore, many thousands of normally pressured shallow gas reservoirs were eliminated by the first screen and no production history obtained. This implies that the potential resource base for enhanced gas recovery is substantially greater.
A process to determine the suitability of a watered-out geopressured gas cap reservoir for application of enhanced recovery is outlined. Working from data available in the public domain this process was applied to ascertain the potential and risk involved in enhanced recovery for over 50 wells. It also was used to determine which ones appeared to be the better prospects.
This paper addresses the identification of a potential gas source that is considered an unconventional resource. The methodology developed to identify watered-out geopressured gas cap wells can be utilized in seeking other types of watere.d-out gas reservoirs with the appropriate changes in the screening criteria.
Enhanced Gas Recovery From Water-Drive Reservoirs—Methods and Economics
Authors: Akindele Femi M. , Tiab Djebbar 
Published: December 2007

ABSTRACT
As the search for additional natural gas continues, recovery of known reserves must be improved if the goal of avoiding shortages is to be met. One area requiring further industry attention for enhanced gas recovery is the reservoir associated with an active aquifer. In reservoirs of this type, pressure maintenance and entrapment of gas by encroaching water greatly reduce recovery.
This paper discusses the mechanism by which the aquifer reduces gas recovery and the magnitude of gas possibly left in place. Three methods of improving recovery are analyzed including (1) planned water production, (2) accelerated gas production and (3) gas replacement/displacement by other gas of lower economic value. The study shows criteria for technical and economic feasibility of the methods. Examples are used to illustrate the evaluation procedures.
Mathematical Field Model Predicts Downhole Density Changes in Static Drilling Fluids
Authors: Sorelle Roland R. , Jardiolin Ricardo A. , Buckley Peter , Barrios John R. 
Published: December 2007

ABSTRACT
A mathematical model requiring a minimum of input data can predict the variation of downhole density and hydrostatic pressure in static drilling fluids. It is a general model for oil and water base drilling fluids and completion fluids. Analysis of the model allows several important conclusions to be drawn about the density behavior of drilling fluids downhole.
Determination of Skin Factors and Flow Capacities of Individual Layers in Two-Layered Reservoirs
Authors: Larsen Leif 
Published: December 2007

ABSTRACT
Methods to determine skin factors and flow capacities of individual layers in two-layered reservoirs are presented. The methods are based on infinite-acting approximations derived for systems without crossflow, but can also to some extent be used to analyze early data from systems with crossflow. Limitations arise if the vertical permeabilities are of the same magnitude as the horizontal permeabilities, or higher. In such cases the methods presented in this paper can be invalidated by effects of crossflow.
For drawdown and buildup analyses we introduce both direct computational procedures and procedures based on trial-and-error plotting. Which procedure to choose in a given situation will depend on the smoothness of the data and the type of analysis being used.
Deep Sea Drilling Instrumented Riser Joint
Authors: Tonda Henri 
Published: December 2007

ABSTRACT
An Instrumented Riser Joint (IRJ) developped to measure critical riser parameters in real time during offshore drilling operations in 1000 m water depth, is described Some characteristical data, provided during drilling operations in 680, 800, 950 m water depth are shown. A second IRJ designed for the 1800 m water depth drilling campaign in the Mediterranean Sea, integrates two new sensors (tool-joint and gas). The 1800 m IRJ and a riser measurement system are discussed.
State of the Art Hydraulic Fracture Stimulation Treatment for a Western Tight Sand Reservoir
Authors: Ahmed Usman , Schatz John F. , Holland Michael T. , Jones Arfon H. , Greenfield Harvey 
Published: December 2007

ABSTRACT
The Pinedale gas field is a tight sand reservoir in Sublette County, Wyoming. A number of wells have been drilled in this field since the 1930's. However, there has been no commercial production because of low initial flow rates and rapid production declines usually associated with low permeability. This field would become attractive if the technological problems impairing development could be overcome. This paper describes a resource evaluation and stimulation research program centered around the drilling of two new wells in the Pinedale Field. The resource evaluation involved a critical review of prior data, geological and geophysical work, laboratory testing of core samples from the new wells, and pre-stimulation and post-stimulation flow testing of the new wells. The stimulation research involved special core testing with candidate stimulation fluids and proppants, field in-situ stress testing for fracture geometry estimates, transient pressure testing for well and fracture evaluation, hydraulic fracture design and implementation, and well deliverability projection. Utilizing the state-of-the-art technology, a total recoverable reserve of 2.8 tcf is now possible from the 90,000 acres of Pinedale Field.
Modeling and Analysis of the CSAMT Geophysical Technique Results to Map Oil Recovery Processes
Authors: Bartel Lewis C. 
Published: December 2007

ABSTRACT
The mapping of enhanced oil recovery (EOR) processes is important to predict process behavior and to be able to exhibit some control of the process for maximizing the stimulation of oil reservoirs. The controlled source audio-frequency magnetotelluric (CSAMT) electromagnetic geophysical technique shows promise for mapping steamfloods and firefloods. Two field trials were conducted, one at a steamflood tar sand oil recovery experiment and one at a fireflood heavy oil recovery process. An initial report of the results was given previously. In this paper, an analysis will be given of the CSAMT results for the two floods along with a comparison with production and post-test results. The result of this work is that the CSAMT technique is a viable technique for mapping these thermal EOR processes. In addition, a discussion of mathematical modeling will be given.
A Statistical Approach for Combining Reservoir Fluids Into Pseudo Components for Compositional Model Studies
Authors: Mehra Rakesh K. , Heidemann Robert A. , Aziz Khalid , Donnelly John K. 
Published: December 2007

ABSTRACT
This paper describes a scheme for combining reservoir constituents into fewer pseudo components for compositional studies. The algorithm is based upon the minimization of the errors introduced in the predicted phase saturations. It requires the generation of a second derivative matrix of the phase saturation with respect to moles present at various expected reservoir conditions, which are then used to calculate the simple correlation coefficient matrix and to establish the criterion for combining the reservoir constituents.
Once determined, the properties of pseudo components are calculated using Lee and Kesler's mixing rule. The interaction parameters required for the two constant equation of state models are calculated using simple mixing rules.
The utility of the proposed scheme is demonstrated by comparing predicted phase saturations for the lumped scheme with the saturations obtained using the full original compositions for three widely different reservoir oils. A one dimensional gas cycling process is also simulated to show that the lumped scheme gives an adequate description of the process.
Compositional Effects on the Adsorption of Surfactant From Aqueous Phases in Equilibrium With a Middle Phase Microemulsion
Authors: Vernet Marc R. M. , Truchetet Remy , Schechter Robert S. 
Published: December 2007

ABSTRACT
Adsorption onto nonporous alumina from an excess aqueous phase in equilibrium with an optimum middle phase microemulsion and the corresponding solubilization have been measured as a function of isopentanol concentration, sodium chloride concentration, and alkane molecular weight for 4-dodecyl benzene sulfonate and 4-tridecyl benzene sulfonate. The concentration of isopentanol was adjusted so that each system was optimal.
A multilinear regression analysis and a designed set of experiments were used to construct contours in the optimal plane--coordinate axes represented by the logarithm of salinity and hydrocarbon alkane carbon number (ACN).
These contour plots showed that at a constant ACN, the solubilization parameter exhibits a maximum and adsorption a minimum when the electrolyte concentration is increased.
Two different surfactants were studied. It was found that the one having the longer hydrocarbon tail yielded a larger solubilization and a smaller adsorption.
Field Facilities for CO2 Tertiary Floods—A Conceptual Design
Authors: Alderman David H. , McFarland Ray M. , McIntyre Jim W. , Minissale Joseph D. , Roye J. E. 
Published: December 2007

ABSTRACT
Amoco Production Company is currently evaluating the economics associated with CO2 flooding in West Texas. In order to complete the economic evaluations, field facilities were designed to provide operational reliability, low maintenance, and a minimum investment cost. This paper will focus on the concepts involved in developing designs for the following major field systems: CO2 DistributionInjection wellsProduction WellsFlowlines and Fluid GatheringSatellite BatteriesGas Gathering
Each of these systems, as well as others, such as water disposal and electrical systems, was the subject of a detailed design study.
The CO2 injection system was designed to distribute dry, dense phase CO2 to the injection wells from a central supply point, using API X-grade pipe in a trunkline network. Surface and downhole injection well equipment was evaluated, as were methods of switching CO2 and water injection.
The major areas of study for the production systems were corrosion control and methods of producing a high gas-liquid ratio (GLR) fluid. Flowlines and fluid gathering systems were evaluated for possible replacement with fiberglass pipe. Satellite batteries were designed to meter and separate gas and liquid production. Conventional separator designs were modified for CO2 service. Comparisons between steel and plastic pipe were made for gas gathering systems.