bluuebunny/crossref_metadata_2025 huggingface dataset:
Variations in Temperature Log Response Based on Tool Sensor Location and Logging Sequence
Authors: Walbe K. A. , Rothman E. M. , Stollar Richard , Harris Perry
Published: December 2007

The temperature log has been utilized as an openhole gas entry detection device for over 40 years in wells of the Appalachian Basin.

The air-drilling of the majority of wells in the Appalachian Basin facilitates the use of this log as a qualitative and, in many instances, a quantitative tool in evaluating gas flow from productive intervals.

Historically the temperature log was run in the hole as a down-pass log with an external temperature sensor mounted on the bottom of the tool. However, advances in tool telemetry during the past decade made possible the stacking of logging tools, thus, the external temperature sensor has been moved on many tool strings from the bottom of the tool string to a more central position in the tool stack. This stacked temperature tool data is now recorded during the secondary up-pass portion of a single logging run in order to facilitate the recording of other logs on the primary down-pass.

In order to compare the effects of sensor placement and logging sequence, multiple runs were made in a Columbia Natural Resources well in Roane County, West Virginia, utilizing a single end-mounted temperature tool and a stacked center-mounted temperature tool run during both up and down-passes through productive gas zones.

The resulting temperature log information showed differences in the temperature profiles that were obtained using different tool configurations and different logging sequences.

The information obtained from these runs can be utilized to better understand certain temperature logging anomalies that appear to be inherent in certain tool configurations and logging sequences.
Sour Natural Gas and Liquid Equation of State
Authors: Mohsen-Nia Mohsen , Moddaress Hamid , Mansoori G. A.
Published: December 2007

The major gaseous impurities in the subquality natural gas sources are acidic components, such as hydrogen sulfide and carbon dioxide. Considering that H2S easily dissociates into hydrogen and elemental sulfur, thermodynamic properties and specially phase equilibria of liquid and gaseous systems containing hydrogen, hydrogen sulfide, carbon dioxide, other acidic components, and light hydrocarbons are of much interest to the natural gas and gas condensate production industries.

In this paper we report the development of a simple and accurate cubic equation of state for prediction of thermodynamic properties and phase behavior of sour natural gas and liquid mixtures. This cubic equation of state, which is based on statistical mechanical theoretical grounds, is applied to pure fluids as well as mixtures with quite accurate results. All the thermodynamic property relations of sour gaseous and liquid mixtures are derived and reported in this report. Parameters of this equation of state are derived for different components of sour natural gas systems. The resulting equation of state is tested for phase behavior and other thermodynamic properties of simulated and natural sour gas mixtures. It is shown that the present equation of state, even though it is simple, predicts the properties of interest with ease and accuracy.
Foams and Surfactants for Improved Underground Storage of Natural Gas by Blockage of Water Coning
Authors: Smith D. H. , Jikich S. A.
Published: December 2007

"Foam" blockage to alleviate water coning during the retrieval stage appears to be the simplest, least expensive, and most easily commercialized foam-based technology for improving the underground storage of natural gas. This paper describes effects of injection rate, surfactant concentration, NaCl salinity, and divalent ions on measured aqueous-phase and gaseous-phase relative permeabilities, as well as why these data are needed for modeling the process and designing single-well field tests.
New Solutions for Wells With Finite-Conductivity Fractures Including Wellbore Storage and Fracture-Face Skin
Authors: Liao Yizhu , Lee W. J.
Published: December 2007

This paper presents new solutions for wells with finite-conductivity fractures including wellbore storage and fracture-face skin damage. An infinite-conductivity fracture is included as a limiting case. The new solutions are obtained numerically by modeling a well with an elliptical finite-conductivity fracture in an elliptically composite reservoir. The new solutions are as accurate as published analytical solutions, which are available only for limiting cases. In addition, this study finds and confirms that an "apparent" skin results in a well with a finite-conductivity fracture and fracture-face skin; this "apparent" skin is larger than the true fracture-face skin. The new solutions presented in this paper can be used to analyze production and welltest data for wells with finite-conductivity fractures including wellbore storage and fracture-face skin. Examples are provided.
Prediction of Gas Well Deliverability From Just a Pressure Buildup or Drawdown Test
Authors: Chase R. W. , Alkandari Hassan
Published: December 2007

Predicting the deliverability of a gas well is normally accomplished by conducting a four-point backpressure test, an isochronal test or a modified isochronal test. All of these methods require testing a well at a minimum of four flow rates. Several researchers have worked to advance the theory of predicting gas well deliverability using a one-point test. Their research focused on the development of dimensionless IPR curves for gas wells similar to Vogel's curve for oil wells.

This paper describes a method for predicting the deliverability of a gas well that requires only pressure build-up or draw-down test data. The method utilizes new dimensionless IPR curves that were developed specifically for hydraulically fractured gas wells. The curves may also be applied to unfractured wells by converting the apparent skin factor obtained from a pressure transient test to an equivalent ratio of external drainage radius to fracture half-length (xe/xf) using the apparent wellbore radius concept. Using the new curves or their general equation, an IPR curve can be constructed. In its simplest application, the new method allows an engineer to predict the AOF of a gas well which, when plotted on log-log paper along with the single stabilized point obtained from the pressure build-up or draw-down test, permits the construction of the stabilized deliverability curve and the determination of its equation.
Reservoir Characterization of an Openhole Cavity Completion Using Production and Well Test Data Analysis
Authors: Jochen V. A. , Lee W. J.
Published: December 2007

This paper presents the development of a coalbed methane reservoir description from the analysis of production and pressure transient data for a producing open hole cavity well and two observation wells completed in the Fruitland Formation in the San Juan Basin, Colorado. Data collected and evaluated include open hole drill stem tests and a post-fracture pressure buildup test for the observation wells and multi-well interference tests and pre- and post-cavitation pressure buildup tests and production data for the cavity completed well. The main objective of the work presented in this paper was to gain a better understanding of the mechanisms controlling gas production from open hole cavity completion wells.

The recent emphasis on evaluating the productivity of open hole cavity completion techniques relative to the productivity of cased hole hydraulically fractured completion techniques makes this reservoir characterization important. A good reservoir description may help quantify an increase in the effective permeability, if any, of the coal natural fracture system and help us to understand the reservoir conditions where cavitation may be a suitable stimulation technique for coalbed methane reservoirs. Suitable reservoir conditions may include high permeability, high pressure or a combination of the two. On the basis of the data analyzed, we found that the open hole cavity completion appears to be characterized best with a reservoir description where an altered zone of higher permeability is present around the radius of the cavity to account for the increase in gas production. We will demonstrate that our reservoir description is reasonable by showing a history match of pressure transient and production (gas and water) data both prior to and after the creation of the cavity. We determined the permeability anisotropy of the reservoir natural fracture or cleat system through the analysis of the pre-cavitation interference tests. The geometry and magnitude of the altered zone were determined by matching the postcavitation pressure profiles of the observation wells. We verified the reservoir description by comparing a production forecast based on this description with observed long term data. This study provides a reservoir description that illustrates how a cavity completion can dramatically improve the productivity of a coalbead methane well.
Analysis of Single-Phase and Imbibition Experiments for Slot and Solution Pores Type of Tight Sand at Various Overburden Pressures
Authors: Arastoopour Hamid , Pakdel Parto
Published: December 2007

Imbibition runs at different overburden pressures have been performed on a SFE2-8707 sample from the Travis Peak formation (slot and solution pore type), with an approximate porosity of 7% and gas permeability of 22 to 37 μd, using our physical model. The experiment continued for several days untill the water flow rate reached the steady state values. The single phase water flow experiments were performed at several inlet and overburden pressures, following the imbibition runs.

The results from imbibition and single phase water flow experiments showed that under different overburden pressures, due to the porous structure changes, considerable amounts of pore closing and opening occurred which resulted in an overall increase in permeability of the sample. However from single phase gas flow experiments an overall decrease in permeability of the sample was observed. Furthermore the single phase transient experiments compared well with steady state runs. This proves the reliability of transient runs which results in significant saving in time and expense for core analysis of tight core samples.
Estimating Permeability Profiles Using Core and Log Data
Authors: Yao C. Y. , Holditch S. A.
Published: December 2007

This paper presents a method to correlate core permeability with open-hole well log data. The model correlates porosity, deep resistivity, shallow resistivity and gamma ray index to permeability and eliminates the need to know values of irreducible water saturation or grain diameter as required in previously published correlations. We provide data from three Gas Research Institute research wells to illustrate the correlation.
A Method for Designing and Predicting the Sucker Rod String in Deviated Pumping Wells
Authors: Xu Jun , Hu Yuren
Published: December 2007

Commonly used methods at present for designing rod pumping unit presume vertical wells and are often applied to the design of deviated wells in field practice. This may be possible to cause substantial errors in the analysis of deviated wells because performance and load-deflection pattern of the rod in deviated wells are different from those in vertical wells. Due to bolehole geometry, curved turbing makes the rod result in transverse displacements which is coupled by longitudinal displacements. In this case, load-deflection calculations become more complicated, and, in general, six components of stress resultant or internal forces may appear at any cross section along the rod. Besides, Coulomb friction between the rod and tubing and contact of the rod with tubing are also serious and difficult problems.
Kinetic Approach to the Oil Recovery Simulation for Heterogeneous Reservoirs
Authors: Izmailov A. F. , Myerson A. S. , Kessel A. R.
Published: December 2007

A new system of kinetic equations is suggested to describe pressure distribution in the reservoir porous medium in the course of oil recovery. The equation system accounts the reservoir characteristics and boundary conditions together with the distribution of injection and production wells. The system solution provides the time-dependent evolution of the reservoir pressure in every site of the reservoir modelling lattice. The Dynamic Percolation Invasion with Trapping model [6,7] is adjusted for the heterogeneous case when the reservoir local characteristics are time- and recovery technology-dependent. The special software is created to simulate and visualize the oil recovery process in 3D. Simulation results are verified in numerous laboratory experiments with sand tanks and in a test field.
Well Log Interpretation of a Devonian Gas Shale: An Example Analysis
Authors: Guidry F. K. , Walsh J. W.
Published: December 2007

Because of the complex mineralogy, calculating accurate values of lithology, porosity and saturation in the Devonian Gas Shale cannot be done with traditional well log interpretation models. Tool response and relative volumes for each of the mineral components must be determined first to then accurately calculate porosity. A technique to analyze well logs in Devonian Shale has been developed by ResTech under a contract with Gas Research Institute. This paper demonstrates the steps and procedures used in this log interpretation methodology. A Devonian Gas Shale from the GRI Comprehensive Study Well Program (CSW No. 1A) is used to illustrate the analysis technique. For further information on the development of the model, refer to "Devonian Shale Formation Evaluation Model Based on Logs, New Core Analysis Methods, and Production Tests", Guidry, Luffel, Olszewski, and Scheper, Transactions SPWLA, 1990.
Dynamic Modeling of Permeability and Small-Scale Stratigraphy in a Core Plug
Authors: Trygstad J. C.
Published: December 2007

System dynamics modeling of flow and rock textures might be helpful for testing hypotheses on changing flow capability of reservoir rock. It is desireable to be able to model changing rock textures and flow capability in the computer because most reservoir rock volume is located away from cored wells and is not accessible for direct observation and measurement.

To use system dynamics modeling, a system must change over time. We know flow pathways change over time, because of diagenetic processes, and because of formation damage and production itself. System dynamics models are constructed by modeling assumptions about present conditions. System behavior, for example flow, is then simulated by changing certain specific conditions. When simulation results do not match our hypotheses, then either our hypotheses are wrong or our basic assumptions of the model are wrong. If simulation results mirror our expectations, then we have an effective model for communicating our assumptions and predictions to others. Thus dynamic modeling tests our ideas and hypotheses, and it communicates these to others. Because modeling is used in most disciplines, organizing geologic information in system dynamics format eases communication of geologic information across disciplines, presenting it explicitly.

A dynamic model that demonstrates interactions among small-scale stratigraphy and flow parameters in a core plug is presented here. It was developed using commercially available STELLA software. In the core plug and in the model, diagenetic processes have modified depositional textures. Data categories are organized into feedback loops according to suggested relative influences on each other. These influences are described by equations or "if-then" statements.
Estimating Recovery Efficiency and Permeability From Mercury Capillary Pressure Measurements for Sandstones
Authors: Owolabi O. O. , Watson R. W.
Published: December 2007

Adequate estimation of the field behavior during primary and enhanced recovery period requires representative laboratory measurements. Moreover, the estimation of the behavior from mercury capillary pressure data is important when routine measurements cannot be performed, as in the case of very small core plugs or drill-cuttings. The estimation is also important when there is need to minimize core analysis cost or when the measurements of the behavior are of questionable accuracy, as in the case of reservoir rocks with microfractures.

The objective of this study is to develop new empirical recovery efficiency and permeability correlations to improve the accuracy of estimating behavior of fluid flow through various layers of sandstone reservoir rocks. The correlations were developed from 450 experimentally obtained mercury capillary pressure measurements, using non-linear multiple regression analyses approach.

The correlations are simple to use and can be used in a reservoir simulator with appropriate rock and fluid property data to predict field production performance. The predictive strength of the new empirically derived correlations for sandstones were found to be superior to the existing correlations for estimating recovery efficiency and permeability.
Formation Evaluation Using Core, Well Log, and Initial Production Data
Authors: Bilgesu H. I. , Ameri Samuel , Aminian Khashayar
Published: December 2007

Accurate description of the porosity and permeability distributions are the key for reservoir performance predictions. The porosity of the formation can be evaluated from the cores and/or well logs while the permeability is usually determined from the cores and/or well tests. Usually cores and well test data is often abundant Therefore, the evaluation of permeability and porosity distributions from well log data in heterogenous formation represents a significant technical as well as economic advantage. However, the evaluation of permeability from well log data represents a difficult and complex problem in heterogenous formation.

The goal of this study has been to develop a methodology for determining porosity and permeability distributions in a heterogeneous formation utilizing geophysical well logs. Granny Creek Field in West Virginia has been selected as the study area in this paper. This field has produced oil from Big Injun Formation since early 1900's. The water-flooding operation was initiated in 1970's and currently is in progress. Well log data are available on substantial number of wells. Core samples are also available from a few wells.

Core samples and the well logs were analyzed to determine permeability, porosity, and water saturation. In addition, the results of core analysis and well log interpretations were complemented by geological information and initial production data to develop a correlation between permeability, porosity, water saturation, depositional environment, and pore type. The results were employed for development of porosity and permeability distributions. The methodology presented in this paper could serve as a guideline for correcting permeability with other rock parameters in heterogenous formations. The complexity of such correlations is directly proportional to degree of heterogeneity of the formation.
Hydraulic Fracturing Design Optimization
Authors: Hareland Geir , Rampersad Paul , Dharaphop Jirapong , Sasnanand Sunthan
Published: December 2007

This paper uses a three-dimensional three stress layer hydraulic fracturing model in conjunction with a fractured reservoir production model to optimize hydraulic fracture design. The hydraulic fracturing model has varying widths along the fracture and has the option to choose constant, linear or parabolic fracture height growth criterion. The fracturing fluid rheology is modeled with a non-Newtonian pressure loss model in the fracture, with the special case being the Newtonian model. The fractured reservoir production model uses an equation formulated from a work by Guo and Evans1,2. In this paper the specific reservoir properties were taken from a tight gas sandstone section of the Mesa Verde formation in Colorado3. It should be noted that the fracturing and production of any oil or gas reservoir can be simulated with this procedure. The fracturing parameters optimized in this paper are fracture length and fracturing fluid pump rate. The economics show that this optimization approach has great promise and that it can predict net revenue.
Well Control Procedures in Deep Water
Authors: Lage A. C. V. Martins , Nakagawa E. Y. , Cordovil A. G. D. P.
Published: December 2007

Well control procedures are revised aiming at the minimization of problems related to kicks and blowouts in deep water operations. The analysis and definition of the most suitable early kick detection methods, well shut-in technique and kick killing procedure are performed to lead us to safer operations.

Kick scenarios are defined and studied with the help of a kick simulator to investigate the influence of some parameters and operational practices in the whole well control procedure. The consequences of flow-check, hard or soft shut-in, and the driller's or engineer's methods of kick control are discussed to serve as the basis for the definition of the most appropriate techniques to be adopted in deep water drilling operations.
Experimental Tests for Gas Kick Migration Analysis
Authors: Lage A. C. V. Martins , Nakagawa E. Y. , Cordovil A. G. D. P.
Published: December 2007

Gas kick migration experiments were performed in a training well for the purpose of analyzing kick behavior under two conditions: open and closed well. The objective was to estimate the migration velocities in each of these situations with no circulation in the well. At present, just the results with air and water mixtures are available. Air and water-base drilling fluids will be used in future experiments.

During the tests in closed well conditions, the casing pressure build-up was monitored at surface. Simplified analysis, which do not take into account the system's compressibility, assume that the gas keeps its pressure as it migrates through the well. However, it was observed that the pressure variation was not so severe. A simple method to estimate it was developed considering mud and gas compressibilities and filtrate losses.

Practical applications of these results include: (1) availability of more precise values of kick migration velocities and pressure build-up estimation to be adopted by field personnel; (2) support for enhancing kick simulators.
Development of Whirl Resistant PDC Bits
Authors: Clayton R. I. , Ivie B. S.
Published: December 2007

The destructive effects of the dynamic forces typically induced by bit whirl have beert identified in previous works. The material presented deals with innovative design features recently developed for PDC bits which resist initiation and propagation of bit whirl.

As stated in previous work, bit whirl can be initiated by both cutter/rock interaction forces and extraneous factors such as formation characteristics and undesirable BHA motions. Previous work has also shown how conventional PDC bit technology provides little resistance to whirl and in many cases may reinforce whirl once initiated.

Several PDC bit features have been identified that improve bit stability. Cutter force balancing, bit asymmetry, gage design, bit profile, and cutter configuration and arrangement can all contribute to eliminating the propagation of whirl. All of these features will be investigated and assessment of their benefits reported.
Reservoir Characterization Using Multiple Formation Pressure Tester: El Furrial Field, Venezuela
Authors: Russo A. J. , Dumont O.
Published: December 2007

ABSTRACT1

The El Furrial field is located in Monagas State, Eastern Venezuela. It was discovered in February 1986 with the drilling of The Furrial-1 well (Ful-1) in the Naricual foraation at a depth of 14,000 feet, which resulted in a potential of 7,000 BPD of oil with a gravity of 27 oAPI (1/2" choke).

The structure of the field is an asymmetric anticline that is cut by reverse faults which run almost parallel to the axis of the structure and by normal cross faults. The Naricual formation is the most important in the structure and contains the largest volume of medium crude which is deposited in a marine environment near the coast. Its thickness ranges from 1,470 to 1,700 feet. This formation is characterized by a marked variation in fluid composition and oAPI gravity with depth, ranging from 29 oAPI at the top of the structure to 8 oAPI on its flanks. The complexity of the field posed a significant engineering challenge to design a plan to obtain information that would, at the lowest assessment costs, clarify the degree of vertical and areal communication between the bodies of sand, characterize the vertical distribution of fluids and optimize the selection of completion intervals. All of this was possible with the use of the tool called Formation Multiple Test (FMT).

This article describes the use of the FMT in the effective characterization of the Naricual foraation and its contribution to the identification of the optimum development strategy for the field.
Computer-Aided Design and Optimization of Sucker Rod Pumping Systems
Authors: Miska S. Z. , Khodabandeh Ardeshir , Rajtar J. M.
Published: December 2007

Predicting the performance of a sucker-rod pumping system is vital for optimizing/designing a system or diagnosing the problems associated with it. An accurate prediction of the system's performance is complicated because of the dynamic behavior of the sucker-rod string and the complex interactions between components of the system.

This paper presents an application of a comprehensive mathematical model that predicts the surface and downhole dynamometer cards, production rates, downhole and surface forces, and energy consumption of sucker-rod pumping systems for a variety of operating conditions. The model is defined by a system of linear algebraic equations. The results of modeling are compared with the actual field measurements. The results show a very good match of the field data. Applications of the model are illustrated by example of the optimization of existing system and the design procedure of a new one.
Experience with the Use of Reeled Tubing in Gas Lift Completion in Lake Maracaibo
Authors: Bortolin L. L.
Published: December 2007

Throughout time changes in the reservoir and economic conditions have motivated the oil industry to develop artificial lift methods.

This paper demonstrates the application of reeled (coiled) tubing to gaslift technology and the addition of another use to the growing list of its service and production capabilities.

The use of coiled tubing In gaslift installations allows the production of many wells without affecting workovers or changes of existing tubulars.

The design parameters, components and actual field results obtained in a pilot project conducted in areas of Lake Maracaibo are discussed.
Analysis of Beam Pump System Efficiency from Real-Time Measurement of Motor Power
Authors: Podio A. L. , McCoy J. N. , Collier F.
Published: December 2007

A systematic study was undertaken in order to establish a procedure by which the effect of operating conditions on the efficiency of beam pumping systems can be determined with a minimum of expense. The study concentrated on the effect of easily controllable parameters such as direction of rotation, counterbalance effect, motor selection, torque mode for variable torque motors, tubing back pressure, stuffing box friction and motor slip on the energy usage.

The paper describes the instrumentation, data acquisition and processing system which allows accurate measurement of instantaneous motor power during a pump stroke. This measurement was correlated with dynamometer measurements in order to determine the surface system efficiency. Calculation of the downhole pump dynamometer allows determination of the effect of operating conditions on the volumetric efficiency of the pump. From these measurements, an overall efficiency can be established as a means of comparison; that is , the overall work output at the pump versus the work input at the motor.
A Method for Diagnosing the Performance of Sucker Rod String in Straight Inclined Wells
Authors: Xu J.
Published: December 2007

Most existing state-of-the-art diagnostic models, that determine the downhole conditions from polished rod data, are based on the limitations of presuming vertical hole and neglecting the rod-tubing rub. Sometimes, the current diagnostic techniques have been found to cause unrealistic results in the wells where excessive rod friction is suspected. This paper presents an improved model of rod motion with combined Coulomb and viscous friction. Using Fourier series, an exact steady-state solution of longitudinal vibrations of sucker rod has been developed analytically. The effect of transverse displacement is calculated with Galerkin energy principles. It provides a uesful tool to diagnose the downhole operating conditions in straight inclined well even in vertical well with severe dog leg.
An Evaluation of Natural Gas Huff ‘n’ Puff Field Tests in Brazil
Authors: Lino U. de R. A.
Published: December 2007

This paper presents an extended evaluation of the results of natural gas huff ‘n’ puff field tests performed in a light oil reservoir in Brazil (in Miranga field, state of Bahia), Both advantages and disadvantages of natural gas and CO2 cyclic injection are compared. The wells submitted to the process presented increase in the oil production in spite of some operational limitations. The cost of the process is vary low, what encourages its application to a larger number of wells in the sate field and in other ones. Some of the reasons to low costs are due to make good use of the available gas lift facilities and the injected gas recovery during production. The process can be applied to in substitution to CO2 cyclic injection with great advantages such as: lower corrosion levels, no contamination of the produced fluids, recovery of the injected gas and lower project costs. The use of natural gas in substitution to CO2 is very attractive because brings the opportunity of spreading out the application of the precess to a larger number of projects than before.
Experience with Electrical Submergible Pumps in Heavy Crude Oil (Boscan Field)
Authors: Bortolin L. L.
Published: December 2007

During recent years, optimization of lifting methods has been applied in the oil industry in order to evaluate the effect on oil well production and establish a company's optimal investment policies.

The higher costs of new artificial lif ting equipment and facilities for new fields have created the necesity to review the latest available technology of different lifting methods and specially that of the electrical submergible pump (ESP).

Few studies in the area of heavy crude oil production optimization using ESP's as a lifting method have been published. This paper discusses the results of a pilot ESP project performed in ten wells in the Boscan field and analyses the performance of the equipment and its application range. This equipment was installed in completions at depths ranging from 7000 to 9000 feet, with a 10° API crude gravity and bottom-hole temperatures of 180°F.

It was concluded that despite a reduction of the pump's efficiency, the ESP equipment does qualify as a good alternative lifting method for heavy oil production. It is also possible to obtain higher production rates.

The results obtained in this project confirms that submergible pump is an alternative method for lifting heavy crude oil from relatively deep reservoirs.
Gas Sales Contracts And Allied Problems
Authors: Thorp John P.
Published: December 2007

The type of transaction to be considered is the sale of a large reserve of high pressure (over 1,000 pound) gas well gas to an interstate market. Delivery will be to a transmission line for transportation and resale outside of the state. Such sales are now under the jurisdiction of the Federal Power Commission.

My presentation will, I hope, be slightly different from the type that has become customary of late years. I don't intend to lay down a barrage of statistics showing how interstate natural gas sales have increased from one trillion cubic feet in 1944 to 6.5 trillion in 1959, or how 16 billion dollars have been spent during this 15 years to build pipelines—now measuring nearly 900,000 miles—you are all as familiar with these figures as I.

There is, however, one statistic which is of tremendous importance to us all in the industry, as well as to the 32 million consumers of natural gas in the United States. This is that during this period the average field price of gas has increased from around 6.8cts to 14cts/MCF. Producers are, as a matter of fact, actually negotiating sales now at around 24cts/MCF, including tax reimbursement, in South Louisiana. While this increase causes concern on the part of Distributors and Consumers, it also causes Management of the Producing Companies to look more closely at the contracts we negotiate.
Estimating Facies and the Permeability from an Integrated Database Using Statistical Methods in the Boqueron Field, North Monagas, Eastern Venezuela
Authors: Sinha A. K. , Deghirmandjian O. , Mendez M. F.
Published: December 2007

In the absence of any direct continuous permeability measurement logging tool, predicting permeability distribution in the field is a difficult task. Standard log-core regression relationships for permeability has its limitations and sometimes provide unsatisfactory results on a field basis. Similarly, facies description on a field wide basis is a costly and time consuming process.

A novel statistical technique is described to estimate a more reliable permeability and facies utilizing an integrated database of well log and core information built by this technique.

A database is built, using information from selected depth intervals in wells having reliable permeability or facies information. This database is then used for estimating permeability or facies in other wells, or other depth intervals in the same well, where data is missing. No predetermined relationships between variables are assumed.

The technique is used in the Boqueron field, located north of Monagas area, Eastern Venezuela. The paper describes the technique and application to estimate the permeability over depth interval where core permeability information is absent. A separate database is built with the facies description and well log data. To estimate the facies in wells where no facies description is available, log data is used to query this category database. The quality control and error involved in the technique are discussed.

The examples shown in this paper will demonstrate that this novel statistical method significantly improves the estimation of the continuous permeability curve and facies description, when compared to traditional methods.
Identification of Productivity Problems in Clastic Sandstone Reservoirs of the Eocene Lower C Group, Block III, Lake Maracaibo, Western Venezuela using Well Log Data
Authors: Coll M. C. , Cortiula B. , Toledo A.
Published: December 2007

Abstracts

Productivity in sandstone reservoirs can be adversely affected by changes in permeability and porosity due to varying cementation materials, diagenetic clays and dual porosity systems. Extended use of conventional log evaluation techniques have resulted in poor well completion strategies and misunderstanding of the log behavoir on the best production pay zones.For improving the well completion strategy, a methodology for quantitative evaluation of this type of reservoir is given. This evaluation is made using core-log correlation,thin section analyses, crossplot techniques and clay volume calculations in order to evaluate effective primary porosity and water saturation using inversion models. This methodology was successfully applied for identifying changes in permeability, clay volume and formation factor in this area and allowing for a reliable estimate of hydrocarbon production capabilities of the Lower C sandstones A case by case study of wells is presented. The productivity of these sandstones is calculated using different evaluation methods and compared with production data from the wells. The excellent correlation between the estimation of well production and actual production data led to a better calculation of the oil reserves and will aid future development plans..
Fracturing with Screen-Out Mode - Optimum Treatment for San Francisco Field, Huila-Colombia
Authors: Chauvez R. Beltrán , Sepulveda E.
Published: December 2007

A great diversity of treatments are attempted every day to restore wells inflow performance relationship, (IPR). For the specific case of Sandstones, chemical type treatments, including Matrix Acidizing, aromatic solvent flushes, emulsifiers and others are pumped under radial flow into the formation to try to dissolve near wellbore damage. However, due to the combined nature and depth into the formation of the damaging mechanisms, chemical type treatments are not always successful.

As an alternative solution, hydraulic fracturing treatments have been performed in numerous Sandstone formations to by-pass damage around the wellbore, even if the formation's permeability is relatively high.

This paper discusses the case of a Sandstone Formation where Hydraulic Fracturing treatments have positively responded to increase the well's productivity index.

Several fracturing treatments performed in this Field over five years, have shown that a change in the design of the fracturing treatments, starting by conventional large volume treatments and ending with very small size jobs with induced screen-out, have lead to better results with respect to productivity index increase and cost savings.
Modification of Relative Permeability Curves by Polymer Adsorption
Authors: Barrufet M. A. , Ali L.
Published: December 2007

A newly developed starch based biopolymer treatment to modify the relative permeability curves is presented. The hydrophilic nature of the adsorbed biopolymer causes a reduction in the water relative permeability while having a variable effect on the relative permeability to the non-wetting phase.

Starch based biopolymers have excellent viscosity in brines. Their viscosity has been found to increase with an increase in the salt concentration in the brine irrespective of the polymer concentration up to 10,000 ppm. Moreover, starch is naturally abundant, cost-effective, and environmentally safe.

Results of laboratory corefloods demonstrate a marked change in the relative permeability curves due to an adsorbed polymer layer in the sand grains. The change of the relative permeability to water is greater than the change of the non-wetting phase relative permeability. The reduction in the water relative permeability, as demonstrated in this study, indicates that starch based biopolymers should be useful in blocking water in production wells, and in plugging thief zones in injection wells while maintaining the polymer treatment cost at its minimum.
Three Modified Calculation Procedures for Estimating Swabbing Effect in Horizontal Wells
Authors: Jorge N.D.M. , Santos O.L.A.
Published: December 2007

This paper presents three modified calculation models for predicting swab pressure when the drillstring is pulled out of a horizontal well. They have been implemented in a computer program and the simulation runs have shown a good agreement of their predictions. The results have shown to be very dependable on the rheological model adopted for the calculations. Two rheological models have been investigated: Bingham and Power Law.

Also, the effects of some variables on swab pressure have been analyzed. The rheological properties of the drilling fluid, the drillstring speed and the length of the horizontal section have shown to have major effects on swab pressure calculations.

A more complex calculation procedure is also discussed in this paper. This procedure includes a transient flow model for a gas reservoir that allows to estimate the amount of gas entering the horizontal well when tripping out.
An Algorithm for the Stochastic Simulation of Sand Bodies
Authors: Suro-Pérez V. , Martinez L. Ramos , Pino A. Villavicencio
Published: December 2007

A Boolean method is presented to simulate 2D sand lobes in a deltaic environment. Two different alternatives are used to define the shapes of geological bodies. The first defines shape using parametric functions. The second considers a discrete representation, defining each shape through a finite set of coordinates. A fast algorithm for yielding unconditional and conditional simulations of these shapes is presented and applied to model actual outcrops in Spain.
Thermodynamic Characterization of Volatile Hydrocarbon Reservoirs by Neuronal Networks
Authors: Briones M. F. , Rojas G. A. , Moreno J. A. , Hidalgo O.
Published: December 2007

In this paper we present the application of the technique of artificial neural networks to the thermodynamic characterization of reservoir fluids.The development of a demarcation system that allows the prediction of reservoir fluid type, (black oil, volatile oil or gas condensate) based on field information from production tests and validated PVT analysis is described.

Neural networks are coarse models of the human neural system an they have been used successfully in solving practical problems of pattern recognition. In this work, a carefully selected data set of eighty (80) gas-oil ratios API gravity and percentage of C7+ composition values, corresponding to black oil, gas condensate and volatile oil were used for training the neural network. The training objective was the recognition of fluid type. The trained system, was validated with two hundred and fifty (250) PVT laboratory test from eastern Venezuela showing an excellent performance in fluid type characterization. The reservoir fluid type forecasts obtained with this approach were found to be outstanding when compared to those made through the application of classifying criteria proposed by other authors. It is concluded that the proposed demarcation system is superior to the previously reported techniques.
Safety and Maintenance Management - An Overview of Program Analysis
Authors: Dey A. K.
Published: December 2007

Direct costs associated with the plant, facility and equipment installation and operation have continued to hold steady for many years, but the indirect costs have gone up significantly. The result of the research provided herein indicates that the indirect costs account for more than 30% of every dollar spent and the safety and maintenance issues account for over 50% of these indirect costs.

This paper provides a synopsis of an overview of the safety and maintenance management program analysis that impacts Oil, Gas and Petrochemical industries in the day-to-day operations. The rationalization and implementation of an effective program management can potentially reduce at least one-third of these costs and save billions of dollars annually for the industries world-wide. The implementation of total quality management (TQM) can extend the benefit which otherwise might not be realized.
Characterizing a Naturally Fractured High Transmissibility Gas Reservoir by Pressure Transient Tests
Authors: Quiroga H. R. , García J. Mellado , Lúquez J. A. , Alvarado R.
Published: December 2007

This paper presents a field case study of a naturally fractured gas reservoir, and describes monitoring and characterizing of a high transmissibility gas reservoir using pressure transient tests. The 6 wells (well system) interfere with each other and have high absolute open flow (AOF). The reservoir gas has a large quantity of high molecular weight hydrocarbons and the current static bottom hole pressure is below dew point pressure. The reservoir was stabilized at constant flow rate (total system) and transient pressure disturbances were generated in each well tested.
Pore Structure Influence on the Electrical Resistivity of Saturated Porous Media
Authors: Grattoni C. A. , Dawe R. A.
Published: December 2007

The incorrect interpretation of electrical resistivity logs in hydrocarbon bearing porous rocks can give rise to gross uncertainties in the estimation of initial oil-in-place. All interpretations are based on Archie's equations which use simple pore geometry concepts. However the equations then have to be modified to reservoir situations by empirical corrections.

The resistivity of a fluid saturated porous medium is certainly intimately related to pore structure but this intimacy as a function of pore structure has not been properly established so as to be incorporated into resistivity interpretation. Experiments with model pore structures can assist in identifying the relevant features. In this paper experiments are reported which show some of these pore scale effects. Transparent sealed etched networks saturated with brine that can represent specific features of porous media have been used and a technique for the measurement of resistivity within the networks has been devised. We have identified the basic elements for describing the pore space needed to model the electrical resistivity of fully saturated porous media. A mathematical network model which uses the same pore structure characteristics as the physical models has also been developed and the experimental data have been successfully compared with the predictions. We show that the pore structure affects the resistivity and it can be correctly modelled. In this way we anticipate the eventual incorporation of pore structure into resistivity interpretation.
Solution of Miscible and Immiscible Flows Employing Element-by-Element Iterative Strategies
Authors: Coutinho A. L. G. A. , Alves J. L. D. , Garcia E. L. M. , Loula A. F. D.
Published: December 2007

In this work, the finite element solution of the flow of miscible and immiscible incompressible fluids is addressed. A block-iterative scheme is used to solve the resulting finite element equations in time, combined with element-by-element iterative techniques, a dynamic mesh partition algorithm where the pressure equation is always implicit and the transport equation may be treated as implicit or explicit, and an adaptive time step control strategy. Numerical experiments on the CRAY Y-MP for five-spot patterns and the analysis of the problem of water injection in a rectangular oil reservoir with small scale permeability variations are performed to demonstrate that the proposed techniques are accurate and result in a very fast code.
Tertiary EOR Design for Vertical Miscible Flood
Authors: Chen S.-M. , Chen L.-W. , George I. R.
Published: December 2007

Since their introduction, the techniques of vertical miscible flooding have gained substantial popularity and have experienced great success in many reefs and thick reservoirs. However, their application has been restricted to secondary recovery processes only. Failures in extending these techniques to tertiary EOR processes lie in the project design, and can often be attributed to problems of severe solvent breakthrough, leading to loss of miscibility, and poor oil recovery.

The objective of this paper is to find solutions to the difficulties with tertiary EOR applications and bring this potentially powerful tool into use.

The following will be discussed Differences between secondary and tertiary oil recovery.Solvent injection processes and miscibility integrity.Formation of the oil bank and production constraints.

Then formulae are derived to calculate: The time required to generate the oil bank prior to the start of oil production.Solvent injection rate and the solvent volume required for the project.Oil and water production rates.The tertiary EOR incremental recovery factor

Finally an example is presented to illustrate the project design process.