bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Early-Time Model for Well Testing of a Hydrate-Capped Gas Reservoir
Authors: Gerami Shahab , Pooladi-Darvish Mehran 
Published: December 2007

Abstract
Natural gas hydrate have been estimated to make up the largest component of fossil fuel resource worldwide. Hydrate reservoirs may be found in different geologic settings including deep ocean sediments and arctic areas. Some reservoirs include a free-gas zone beneath the hydrate, and such a situation is referred to as a hydrate-capped gas reservoir. Gas production from such a reservoir could result in pressure reduction in the hydrate cap and endothermic decomposition of hydrates.
Well testing in a hydrate-capped gas reservoir is a developing art; development of a new model, incorporating the dynamic effects of gas hydrate decomposition, is necessary for realistic and accurate predictions. This paper presents a twodimensional (r,z) mathematical model for a constant rate drawdown test performed in a well completed in the free gas zone of a hydrate-capped gas reservoir during the early-time period of production. Using energy and material balance equations, the effect of endothermic hydrate decomposition appears as an increased compressibility in the resulting governing equation. The Laplace-domain solution for the dimensionless wellbore pressure is derived using Laplace and finite Fourier cosine transforms. The solution to the analytical model was compared with a numerical hydrate reservoir simulator over some range of hydrate reservoir parameters.
The results show that the effect of decomposition on wellbore pressure is substantial. The analytical model can be used for analysis of drawdown tests in hydrate-capped gas reservoirs. Furthermore, it may be used to quantify the contribution of hydrate decomposition on production performance.
Methods for Upscaling Diverse Rock Permeability Data for Reservoir Characterization and Modeling
Authors: Shafer John L. , Ezekwe Nnaemeka John 
Published: December 2007

Abstract
The primary sources of rock permeability data are cores and logs. Core-based permeability data are sampled from the reservoir at different scale from log-based permeability data. Consequently, porosity-permeability cross-plots from core plugs and logs are sensitive to the methods used in averaging the permeability data. For instance, arithmetic averaged core permeability data translated to log scale can be an order of magnitude greater than the core plug data at a given porosity. Using Dykstra-Parsons coefficient as a measure of reservoir heterogeneity, arithmetic averaging of permeability data is not suitable as the rock becomes more heterogeneous. Other methods such as geometric or harmonic averaging may be more appropriate.
Core heterogeneity below the vertical resolution of log NMR measurements has an impact on the methods used to calibrate NMR permeability data using core data. A method presented in this paper compares core permeability data with the NMR permeability data to account for sample volume differences utilizing high-density mini permeameter or high-density RCAL permeability data with different averaging techniques to simulate the vertical resolution of the NMR log.
This paper demonstrates the impact of averaging methods on upscaling permeability from core to log scale. Several unique methods for scaling up permeability data of heterogeneous rocks for reservoir characterization are recommended. These methods will generate more realistic characterization of reservoir models in terms of distributions of permeability property in the models.
The paper compared kh (permeability-thickness product) calculated from mini-DST tests to those calculated from core and profile (mini-permeameter) permeability data. The results of the comparisons are inconclusive. The kh from the mini-DST tests are not correlateable to those calculated from profile permeability data. The differences in kh values are traceable to uncertainty associated with depth shifts and the difficult task of ensuring that we are actually comparing data from the same depths or formation intervals.
Using a New Artificial-Lift System in Mexican Mature Oil Fields
Authors: Vann Roy R. , Gachuz-Muro Heron , Alcazar-Cancino Luis O. , Guerra-López Mauricio 
Published: December 2007

Abstract
Throughout Mexico there are many oil wells in danger of being plugged or abandoned. These mature wells could possibly be made economical again by employing a new oil well pumping system using cable instead of rods. This pumping method is designed as an alternative to conventional "rod and pump jack methods" utilized in oil wells. Instead of rods to convey the up and down stroke of the downhole pump, cable is used. In place of pump jacks, an electronic and hydraulic operated system is employed with no visible moving parts on surface equipment. The pumping method unconventional offers many options and advantages that conventional pumping does not offer.
The system is designed to operate safely and environmentally pleasing with low noise operation capability and a clean wellsite appearance with no oil leakage. In addition, an economic value is recognized when maintenance is required. A special cable unit is brought out to reel up and repair the downhole pumping assembly and return it to bottom; no workover unit is needed.
This method has been developed and tested in Tyler, Texas for approximately seven years. Recent results in Mexico have shown many advantages. This paper presents various aspects (evaluation, development, working principle, etc) of this system and the field test results in Mexican Mature Oil Fields. The versatility of its characteristics has allowed us to maintain oil rates and reduce operational costs. This system discusses its difference with "conventional methods" and impact on production behavior.
The Effectiveness of Geochemical Technique for Evaluation of Commingled Reservoir: Case Study
Authors: Nengkoda A. , Widojo S. , Mandhari M. S. , Hinai Z. , Khan T. 
Published: December 2007

Abstract
The X gas field of PDO is currently contributing of Oman's gas requirements for LNG export. The field is producing from the rich gas-condensate bearing Reservoir A and lean gas bearing Reservoir B and Reservoir C sandstone. The total number of wells until to date is 23 development wells drilled in the field, of which 11 wells are on production, 6 wells produce from Reservoir A only, 1 well from Reservoir B only, 3 are commingled Reservoir A, B and C, 1 well from Reservoir A and C, and last, 1 well from C. The average formation split from the field predicted 45% Reservoir A, 20% Reservoir C and 35% Reservoir B, and in specific is vary from well to well and however it is depend on the drawdown. The primary surveillance tool is used to allocate a relative production for two reservoirs by utilizing a MPLT surveys. And recently, a campaign of multi-phase flow meters coupled with PLT's was initiated. Gases in Reservoir B and C reservoirs of Oman have very different carbon isotope character than those in Reservoir A. These differences are unique and can be used to calculate mixing proportions of commingled production. The proposed solution to this problem was the derivation of two and three case models that accounts for variable isotope and composition characteristics, and trending in which all such data could be correlated. The effectively of this geochemical technique is captured from this study.
Hierarchic Modeling and History Matching of Multiscale Flow Barriers in Channelized Reservoirs
Authors: Li Hongmei , Caers Jef 
Published: December 2007

Abstract
Channelized reservoirs often consist of multi-scale architectures containing large-scale channel belts, middle-scale single channels and small-scale channel infill components. These architectural elements are defined between bounding surfaces. Along these hierarchical bounding surfaces, thin shale drapes may be present as flow barriers that compartmentalize the reservoirs. Since the distribution of shale drapes is dominated by these bounding surfaces they themselves form a multi-scale reservoir heterogeneity. Characterizing the distribution of these multi-scale flow barriers calls for a hierarchical modeling and history matching approach to integrate all data available. In this hierarchic approach the large-scale reservoir architecture is modeled first, the shale drapes are then simulated within this architecture framework.
The reservoir architecture modeling in this paper involves defining channel deposition fairways (valleys) based on seismic data, modeling long sinuous channels and placing them into defined fairways such that all data are matched. This paper adopts a stratigraphic-based modeling approach. In this stratigraphic-based approach, individual channels are simulated using the YACS method (Alapetite et al., 2005). This method is fast and conditions to well data under the assumption that channel sand can be identified in the well data. To stack multiple channels reproducing a desirable stacking pattern, the migration ratio and overlap ratio are used as input parameter of the simulation process. Once the large-scale reservoir architecture is modeled, the bounding surfaces are record, next, the shale drapes are simulated along these surfaces using multiple-point statistics techniques. To match the production data, channel location and the number of channels are perturbed using the gradual deformation method, the continuity of shale drapes is perturbed using the probability perturbation method.
A 3D synthetic example is presented to demonstrate this modeling approach: the multi-scale shale drapes are modeled and perturbed while the reservoir geological concepts are preserved. This hierarchic modeling approach allows integrating different data at their relevant scale.
Humans Are Not Responsible for Global Warming
Authors: Chilingar G. V. , Khilyuk L. F. 
Published: December 2007

Abstract
The global drivers that determine the Earth's climate are: (1) solar radiation as a dominant energy supplier to the earth, (2) the Earth's outgassing as a major supplier of gasses to the hydrosphere and atmosphere, and, (3) possibly microbial activities generating and consuming atmospheric gases at the interface of lithosphere and atmosphere. The authors provide quantitative estimates of the scope and extent of their effects on the Earth's climate. Comparison of these estimates with the corresponding anthropogenic effects shows that the human-induced climatic changes are negligible with respect to global forces of nature. One should not ignore the fact that peaks in solar irradiation precede peaks in CO2 concentration. Using the adiabatic model developed by the famous Russian Scientist, Dr. O.G. Sorokhtin, the authors show that the increase in CO2 concentration in atmosphere will result in cooling rather than warming. Thus, the attempts to alter the global climatic changes (and drastic measures prescribed by the Kyoto protocol) have to be abandoned as meaningless and harmful.
Experimental Investigations of Ultrasonic Waves Effects on Wax Deposition during Crude-Oil Production
Authors: Towler Brian F. , Chejara Ashok Kumar , Mokhatab Saeid 
Published: December 2007

Abstract
One of the problems that plagues oil companies is the deposition of wax or paraffin inside pipelines. The present invention is a method for mitigating the wax deposition during crude oil flow in a well-bore or pipeline. The method comprises positioning one ultrasonic frequency generating device adjacent to the production tubing walls and producing one ultrasonic frequency thereby disintegrating the wax and inhibiting the wax from attaching to the production tubing walls. Experiments were done to measure the effect of ultrasonic waves at a frequency of 120 kHz on wax deposition during crude oil flow in a pipeline. In this paper, all the experimental results are described. Some reduction in wax deposition was also achieved due to the ultrasonic waves. Further work is required to identify the optimum frequencies.
The Extraction of Mud-Stuck Tubulars Using Vibratory Resonant Techniques
Authors: Gonzalez Ozzie , Bernat Henry , Moore Paul 
Published: December 2007

Abstract
Stuck pipe has been identified as the largest single contributor to non-productive drilling time. The use of resonant vibration as a means of freeing stuck tubulars from a well bore has been demonstrated to be effective in both Drilling and Workover environments and has the potential to provide almost immediate results in many day-to-day applications. The challenge for the future is to further explore both proven and potential applications of this technology in order to evaluate the benefits and reduce the unknown associated with the technology. The long term industry benefit will be a new approach to stuck tubular recovery available in the form of superior technology that addresses real needs while substantially reducing costs. The technology offers the benefits of being quick and easy to apply, operations are conducted from surface with no downhole intervention, and results may be achieved very quickly. Good success in open hole work could mean that this technology could become the procedure of choice in virtually all drilling operations. In workover operations, the technology may accomplish the same results in hours that typically require days by current standards.
Quantitative Optimization of Offshore Fire and Gas Systems Design Using IEC 61511 (ANSI/ISA-84)
Authors: Raju C. R. 
Published: December 2007

Abstract
Application of performance-based standards viz. IEC 61508 and IEC 61511 in offshore FGS has been a matter of debate since the inception of these codes. Most of the safety practitioners are reluctant to apply these codes to offshore FGS due to reasons like FGS is a mitigation layer, difficulty in achieving even SIL 1 in gas detection loops, scarcity of certified components and difficulties of quantification. Lack of importance of FGS in onshore installations is also one reason in the case of onshore installations.
FGS is a protection layer in offshore oil and gas production offshore platforms as important as important as ESD systems. FGS is a most important mitigation as well as ESD IPL too. Quantification techniques of IEC 61508 and IEC 61511 like SIL determination and SIL evaluation can be effectively used in FGS of offshore platforms. This will lead to more efficient design of FGS systems than designs based on API 14 series and other prescriptive codes and user policies based on qualitative judgments.
Reservoir Technical Limits: A Framework for Maximizing Recovery from Oil Fields
Authors: Smalley P. Craig , Ross Bill , Brown Chris E. , Moulds Tim P. , Smith Mike J. 
Published: December 2007

Abstract
Maximizing recovery is an important part of responsible asset management and of optimizing value from an incumbent resource position. BP's Reservoir Technical Limits (RTL™) process has proved highly effective at estimating oilfield maximum recovery potential and identifying/prioritizing specific activities to help deliver it. This paper describes the process and examples of how it has worked and can be applied.
RTL incorporates a conceptual framework with supporting software, designed to stimulate and structure a conversation with the asset team in a workshop environment. Key ingredients are: in-depth knowledge/experience of the cross-disciplinary asset team; trained facilitation; cross-fertilization from external technical experts; a toolkit to encourage innovation in a structured and reproducible manner. The RTL framework represents recovery factor as the product of four efficiency factors: Pore-Scale Displacement (microscopic efficiency of the recovery process); Drainage (connectedness to a producer); Sweep (movement of oil to producers within the drained volume); Cut-offs (losses related to end of field life/access). Increasing recovery involves trying to increase all of these efficiency factors. RTL builds upon the opportunity set already contained in the Depletion Plan. New opportunities are identified systematically by comparing current/expected efficiency values with data from high-performing analogue fields, seeding ideas with checklists of previously successful pre-screened activities. The identified opportunities are prioritized based on size, cost, risk, timing and technology stretch, and then validated by recovery factor benchmarking: (a) internally, comparing bottom-up (summing opportunity volumes) and top-down (from efficiencies) values; and (b) externally, by comparison with analogue fields.
The result is a prioritized list of validated opportunities and an understanding of how each activity affects the reservoir to increase recovery. The activities (and any required new technologies) are valued in terms of the resultant incremental barrels. Case studies demonstrate the effectiveness of RTL in stimulating activity in individual fields and focusing corporate technology resources into high-impact areas.
The RTL framework is a significant innovation towards increased recovery factors. It is a new medium to focus the talent of the asset team onto life-of-field value, generating an opportunity set of real activities that the team can start to progress immediately.
Characterization of Oil/Water Flows in Horizontal Pipes
Authors: Vielma M. , Atmaca S. , Sarica C. , Zhang H. -Q. 
Published: December 2007

Abstract
The dynamic characteristics of oil-water flow systems have not been fully understood. The need for improved design methods has led researchers towards its continuous investigation. The objective of this study was to characterize oil-water flow in horizontal pipes. The tests were conducted in a 2-in. horizontal test section using Tulsa City tap water and a mineral oil (density = 0.85 g/cm3 and viscosity = 15 cp) with superficial velocities ranging from 0.025 m/s to 1.75 m/s. Various data were acquired on flow patterns, pressure drop, phase fraction and droplet size as function of flow patterns and were used in characterization of the flow and performance evaluation of an oil-water model. A high speed video camera was used to identify flow patterns, measure droplets and ten conductivity probes were used to obtain phase distributions.
New experimental data on pressure drop, holdup, phase distribution and droplet size distribution in oil-water flows are presented. Three probabilistic distributions were tested for fully dispersed flows. Sauter Mean Diameter (SMD) analysis were conducted across the pipe diameter. Droplet size data were used to evaluate existing models such as Hinze1, Kubie and Garner2, Angeli and Hewitt3, and Kouba4. An empirical correlation to predict the SMD profile of droplets across the pipe cross section was developed for flow pattern of dispersed oil in water and water (D o/w & w). Log-normal distribution was the best probabilistic distribution for representing the data for fully dispersed systems. The empirical correlation gave acceptable results. Model comparisons revealed that none of them could accurately represent the experimental data.
The new data can lead to better modeling and design of dispersed systems and the new information on droplet sizes can have significant impact on separator design. Moreover, the interpretation of production logs in horizontal wells heavily relies on the flow behavior.
Consistent Black-Oil PVT Table Modification
Authors: Singh Kameshwar , Fevang Øivind , Whitson Curtis H. 
Published: December 2007

Abstract
This paper presents a physically consistent approach to modify black-oil PVT tables for (1) eliminating, in some cases, so-called negative compressibilities, (2) extrapolating saturated and undersaturated properties to conditions beyond the limits of original PVT tables, and (3) guaranteeing physical consistency of gas and oil properties as a critical condition is approached.
For a number of reasons a black-oil PVT table may contain inconsistencies that result in non-physical behavior in reservoir simulators, sometimes leading to slow run times and, sometimes, premature run termination. Physical inconsistencies can even arise when the black-oil PVT table is created by a physically-consistent EOS model. Black-oil behavior can also be inconsistent as a result of the method used to create the tables – e.g. correlations, conversion of laboratory data, or using EOS models where gas and oil phases are not in thermodynamic equilibrium.
Three main methods are developed in the paper. First, an analysis of negative compressibilities is given and an approach to eliminate the problem is proposed. Negative compressibilities can arise because derivatives are held constant from one pressure table point to the next, inconsistent with the pressure-dependent evaluation of properties themselves.
The second contribution of our paper is a method to extrapolate an existing black-oil table to higher saturation pressures than found in the original table. Extrapolation is possible to any higher pressure – including a critical ("convergence") pressure where phase properties become identical. The proposed method uses a piecewise-linear log-log relationship between black-oil (surface gas and surface oil) K-values and pressure.
Our final contribution is a consistent method to calculate saturated and undersaturated black-oil PVT properties at interior and extrapolated pressures to those in the original table. A cubic EOS and the LBC viscosity correlation methods are used to provide physical consistency, even approaching a critical condition where gas and oil properties must become equal.
Vertical Sweep Evaluation in the Lost Hills Diatomite Waterflood Using Carbon/Oxygen Logs
Authors: Badruzzaman A. , Badruzzaman T. , Morea M. F. , Julander D. J. 
Published: December 2007

Abstract
We discuss our experience to date with the Carbon/Oxygen logging technique to determine vertical sweep in Belridge Diatomite in the Lost Hills Field. We describe early interpretation challenges with overly optimistic saturation estimation. This required in-house Monte Carlo modeling to understand the tool response in very high porosity reservoirs. A newer vendor algorithm, however, underestimated the oil saturation. In-house test algorithms were then developed with significantly more accurate estimation of the oil saturation from a centralized-detector C/O tool in water-filled boreholes; results reported here are primarily for this tool. The C/O technique is also being tested in producers using the corresponding focused tool; we include an example of a successful test of the tool in an uperforated well. The paper identifies further development needed to use C/O techniques, especially the focused tool, optimally in either monitor or producer wells in diatomite.