bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding Flow Paths—New Opportunities From Time-Lapse Seismic Data
Authors: Thedy E. A. , Salomão M. C. , Corá C. A. G. , Santos M. S. , Pumputis A. , Gomes R. M. , Caletti L. 
Published: December 2007

Abstract
After producing 400 million barrels of oil along the last five years, Marlim Sul field, situated in Campos Basin, Brazil, applied its first time-lapse seismic acquisition. The oil is being produced from six different reservoirs, each one with different characteristics. The main common point of them is the water drive mechanisms, and therefore the flow path of the injection water is the prime purpose of this 4D action. Almost all producers have seen the breakthrough of water, sometimes after the forecasted time, sometimes before. The seismic data were acquired by a streamer steering system and received special attention in terms of velocity analysis and crossequalization process. The preliminary analysis indicates some interesting conclusions. The water path seems to be less regular than expected from flow simulation and indicates a trend in rock permeability. This knowledge allows a better match of the model, and a better control of production and injection rates. In addition, some areas are less flooded than expected, wich permits the proposal of new infill drillings, in order to recover this additional oil, depending on the economic analysis, as well as a new infill well, proposed before the acquisition, is not in the better position, and may be relocated or cancelled. Furthermore, the communication of two blocks, situated one above the other, was strongly suggested by the presence of an anomaly related to increase of gas saturation in the higher block derived from the depletion of the lower one. These simple conclusions reveal the power of time-lapse seismic acquisition, and evidence the importance of a permanent reservoir monitoring for the optimization of recovery factor and the profitability of the exploitation project.
A Gun Jump Model for Underbalance Perforating
Authors: Zazovsky Alexander , Zhan Lang , Kusumadjaja Aming , Chewyam Johan Komarudin 
Published: December 2007

Abstract
A new methodology for evaluating the risk of gun jump during post-perforating surge is proposed and tested against field data. This methodology is corroborated by an advanced mathematical model of transient flow into the wellbore triggered by the creation of perforation tunnels under static underbalance and fully coupled with evolving transient flow inside the wellbore containing the gun string. The model predicts the viscous drag on the tool string and the gun string dynamics, which may induce cable tangling or breaking owing to gun jump. This model is used to mitigate the risk of gun jump by varying perforating job design options such as shot density, thickness of the perforated interval, and height of the liquid cushion. Examples of model application to the analysis of field data from Indonesia are provided.
Improved Convergence Efficiency in an Assisted-History-Matching Experiment
Authors: Keating James F. , Ozdogan Umut 
Published: December 2007

Abstract
This study is an attempt to justify the increased performance of an assisted history matching experiment with plausible concepts. These concepts were based on patterns within the error vector (the unique distributions of the error components).
The observed patterns were very similar to patterns seen while using Error Surface Analyses (ESA) to manually history match models. ESA is the animation of errors at their respective spatial locations though time. This error analysis can easily identify locations or times with high errors. During manual history matching with ESA, the efforts are placed on removing the highest errors. In this automatic history matching experiment, the same systematic approach was found when the convergence efficiencies were high.
In this experiment, a simple parametric search routine was used to compare the performance of a data weighted (DW-L2) to an equal weighted (EW-L2) objective function. The data weighted objective function tended to reduce the highest errors first. Results of multiple history matching trials showed that the automatic history matching became more efficient (less simulations) when the data weighted objective function was used. The comparison was made using a conceptual reservoir with ten years of production history under a peripheral water injection. The uncertainties associated with the synthetic reservoir were, (1) the number and sealing capacity of the faults, (2) permeability magnitude, (3) net-to-gross, (4) vertical to horizontal permeability ratio, and (5) relative permeabilities.
Change in Patterns in the Application of a Vertical Drilling System (Stabilized Drilling System) VDS in the Basin of the Gulf of San Jorge
Authors: Speranza Cesar , Fontana Adrián , Marquez Hugo , Crovetto Marcelo , Wallace Cameron 
Published: December 2007

Abstract
This paper will present case histories of the successful development of a novel stabilized drilling system developed to reduce drilling time and improve drilling program economics in wells drilled in the basin of the Gulf of San Jorge.
A program of drillstring stabilization was developed that combines technologies proven in other drilling applications, with the goal of reducing maneuvering time, drill-bit changes, and time spent on well logging while improving wellbore quality. Substantial improvements in the wellbore gage quality and reduced tortuosity contributed to reduction in trip times, better wellbore calipers, increased ROP with fewer bits used, no electrical logging set up incidents, and no incidents in subsequent casing and cementing operations.
Modeling Two-Phase Flow in Porous Media With Consideration of Jump Interfaces
Authors: Peng Xiaolong , Du Zhimin , Liang Baosheng , Qi Zhilin , Wang Wei 
Published: December 2007

Abstract
Discontinuities of rock and fluid properties are very common in the reservoir due to variations of formation lithology and oil-water gravity differentiation. Fluid discontinuity also exists at the water front in the water-flooding reservoir. Interfaces with discontinuous fluid properties are called jump interfaces. It is known that fluid flow at these jump interfaces is neither continuous flow, which is dealt with conventional multiphase flow model in porous media, nor purely piston-like drive, which is the problem of dynamic interface tracking. In practice, however, by neglecting jump interfaces, fluid flow is widely treated as continuous flow by adding relative permeability into each phase equation in black oil simulation. Also, single-point upstream weighting and high order schemes have no improvement on flux rate and moving speed of phase interfaces.
This paper starts from analyzing two-phase flow with consideration of jump interfaces. In porous media, flow channels of oil and water are relatively stable at low rates: one fluid always takes first priority of displacing the same type of fluid and then displaces the other fluid when the channels of the same type of fluid are not sufficient. Therefore, the flow of a specified fluid through jump interfaces includes two parts: displacing the same type of fluid and displacing the other type of fluid. Based on this analysis, we develop a new two-phase flow model, considering discontinuities of flow properties. Unlike currently available flow models, our model takes account the effect of one fluid displacing the other fluid across jump interfaces.
We apply to a 1-D case and compare with Buckley-Leverett equation. The example demonstrates that our new model has more capabilities to describe the physical flow at the jump interface. We also discuss applications of our model on connection condition construction for jump interfaces in the numerical model and relative permeability measurements.
Developing and Field Implementation of a State-of-the-Art BHA Program
Authors: Chen David C-K. 
Published: December 2007

Abstract
This paper presents the development and field implementation of a state-of-the-art bottomhole assembly (BHA) program using the industry's first generic algorithm based on Lubinski's equations. The strengths of the new BHA program are accuracy and computation efficiency, as compared to the conventional finite-element based BHA programs. In addition, the new program integrates static and dynamic models so that users can run both models in the same application. Using the new algorithm, the static model is designed mainly for directional drilling applications, such as optimal BHA design for maximum steerability, bending moment calculations to minimize fatigue failure, and BHA sag corrections to improve survey quality. The dynamic model is based on a hybrid of analytical and finite-element methods to calculate the critical rotary speeds of the BHA. This paper describes the significance of applying these features in a user-friendly application to maximize drilling performance.
Dynamic Nodal Analysis in Well Testing Interpretation
Authors: Schindler Miguel H. 
Published: December 2007

Abstract
In well testing, the subject of study is composed by the reservoir, wellbore and piping.
The traditional well testing interpretation approach focuses in the transient behavior of the pressure inside the reservoir. Flow rates are considered input information; generally assumed instantaneously constant during each flow period.
On the other side, the traditional nodal analysis concentrates in the pressure drops inside the wellbore and pipelines reducing the behavior of the reservoir to a pseudo-stationary state.
These simplifications can be applied for a limited period of time in high potential wells.
However, especially in low potential wells, the productivity index varies continuously, flow rates can not be approximated by constant values; the effects of liquid loading, slugging, and other regimes of multiphase pipe flow affect decisively the conditions in the reservoir. Understanding system's operation implies the analysis of every component and the relations between them.
Advances in After Closure Analysis for Naturally Fractured Reservoirs
Authors: Uribe O. , Tiab D. , Restrepo D. , Chipperfield S. 
Published: December 2007

ABSTRACT
Using the theory of impulse testing and principle of superposition, Nolte et al [1] developed a method which allows the identification of radial flow and thus the determination of reservoir transmissibility and reservoir pressure. The exhibition of the radial flow is ensured by conducting a specialized calibration test called mini-fall off test. Benelkadi and Tiab [2] proposed a new procedure for determining reservoir permeability and the average reservoir pressure in homogeneous reservoirs. In this paper, the procedure is extended to naturally fractured reservoirs.
A new method for the determination of reservoir transmissibility using the after closure radial flow analysis of calibration tests was developed based on the pressure derivative. The primary objective of computing the pressure derivative with respect to the radial flow time function is to simplify and facilitate the identification of radial flow and the characteristic trough of a naturally fractured reservoir. The proposed method does not require a-priori the value of reservoir pressure. Only one log-log plot is used to determine the reservoir permeability, average pressure, storativity ratio, and interporosity flow coefficient.
The technique is presented as a step-by-step procedure, with appropriate equations and graphs. The log-log diagnostic plot of pressure and the pressure derivative is employed here as the main tool to identify the radial flow regime and determine properties of a naturally fractured reservoir (i.e. permeability, interporosity, storativity ratio, and average reservoir pressure). The application of the proposed method is demonstrated on real field data from calibration tests.
The main conclusion of this study is that small mini-fracture treatments can be used as an effective tool to identify the presence of natural fractures and determine reservoir properties.
Permeability Estimation Using Hydraulic Flow Units in Carbonate Reservoirs
Authors: Bagci A. Suat , Akbas Ceylan Yildirim 
Published: December 2007

Abstract
This study focuses on the evaluation of formation permeability for a carbonate reservoir from well logs and core data using the concept of flow units. Characterization of carbonate reservoirs by flow units is a practical way of reservoir zonation. The study represents a petrophysical-based method that uses well loggings and core plug data to delineate flow units within the most productive carbonate reservoir of Derdere Formation in Y field, Southeast Turkey. Derdere Formation is composed of limestones and dolomites. Logs from the 5 wells are the starting point for the reservoir characterization. The general geologic framework obtained from the logs point out for discriminations within the formation. 58 representative core plug data from 4 different wells are utilized to better understand the petrophysical framework of the formation. The plots correlating petrophysical parameters and the frequency histograms suggest the presence of distinctive reservoir trends. These discriminations are also represented in Winland porositypermeability crossplots resulted in clusters for different port-sizes that are responsible for different flow characteristics. Although the correlation between core plug porosity and air permeability yields a good correlation coefficient, the formation has to be studied within units due to differences in pore-throat sizes and reservoir process speed.
Linear regression and multiple regression analyses are used for the study of each unit. The results are performed using STATGRAPH Version Plus 5.1 statistical software. The permeability models are constructed and their reliabilities are compared by the regression coefficients for predictions in un-cored sections.
As a result of this study, 4 different units are identified in the Derdere Formation by using well logging data, and core plug analyses with the help of geostatistical methods. The predicted permeabilities for each unit show good correlations with the calculated ones from core plugs.
Successful Application of a High Temperature Viscoelastic Surfactant (VES) Fracturing Fluids Under Extreme Conditions in Patagonian Wells, San Jorge Basin
Authors: Fontana Cristian , Muruaga Enrique , Perez Daniel , Cavazzoli Gustavo , Krenz Angeles 
Published: December 2007

Abstract
The San Jorge Basin is characterized by multilayer formations requiring proppant fracturing as a completion method in order to achieve oil production at commercial levels. As fields are arriving to a mature stage they require continuous improvements with regards to fracturing techniques.
Typically viscous polymer based fluid had being used with acceptable results for proppant transport and fracture placement; however these fluids are known to generate undesired effects such as uncontrollable height growth, significant proppant pack damage, lengthy clean up times and high friction pressures.
In recent times, polymer-free viscoelastic surfactant-based (VES) fluid systems have been introduced in the industry as an improvement over polymer-based fluid. Nevertheless, VES were known up to now, for their limitation to withstand elevated temperatures. Detail laboratory studies proved that a novel VES high temperature (HT) version was also feasible for the given conditions of this high temperature formation. Since the reservoir temperature exceeded the technical limits of even this HT fluid, simulations indicated that a series of cool-down brine stages would allow the application of this fluid at this temperature (280F). The characteristic of the fluid allowed the treatment to be confined in the limited layer thickness between weak barriers avoiding growth into water - or non - productive zones, resulting in reduced fluid and proppant volumes. Field implementation proved also to be successful in terms of operational simplicity, reduced clean up time and consequently work over rig cost savings. Overall, the use of polymer-free fluids improved well productivity. Design, laboratory studies, temperature simulations confirmed by downhole measurements, field implementation and results of the first VES HT fluid application in the El Tordillo field are presented in this paper. Four different zones were successfully treated in the first well application at various reservoir conditions presenting a wide range of permeability and temperatures.
Surveillance Planning: The Key to Managing a Mature Gas Reservoir
Authors: Samsundar Kamal , Moosai Roshni , Chung Ronald 
Published: December 2007

Abstract
The Mahogany field in Trinidad and Tobago was developed as a dedicated gas field with reserves of 2.6 TCF to supply gas to the Atlantic LNG Plant in 1999. The reserves are deposited in a number of stacked sands, all of which must be optimally produced in order to achieve a successful depletion of the field. To date over 1 TCF has already been produced through a rigorous depletion management system and a renewed effort has been made to ensure that the remaining reserves are not at risk as the field enters the mature stage of its development.
One of the foundation processes that were used in the development of the field was that the right level of surveillance existed and maintained. Acquiring the right surveillance data was considered when designing the wells and facilities. In fact the field is operated in a manner that ensures surveillance data is collected when required, without compromising production or plant integrity. The result of this rigorous surveillance planning and the application of data collected have provided the assurance around delivering the remaining Mahogany reserves.
This paper will discuss the importance of surveillance planning as it relates to maintaining the base production as well as the key issues that should be addressed when forming a surveillance plan. It will also highlight the successes of proper surveillance planning as well as the actions that can be taken to overcome the challenges faced when developing a surveillance plan.
Monitoring and Controlling Paraffin Deposition by a Direct Assessment Technique
Authors: Gomez D. Carlos I. , Medina F. Eduardo J. , Patiño Edgar 
Published: December 2007

Abstract
This paper presents the results of the evaluation of paraffin control treatments applied in rod pumped wells in La Concepcion oilfield, located at the western of Venezuela and operated by Petrowayuu, which is a mature field with paraffin deposition problems.
Before the study, the only treatment applied on the wells to control paraffin deposition was hot watering. Because the average production rate of the wells was 30 BFPD, the application of high volume treatments, as hot watering, implied production deferral due to their low productivity index (around 0.09 BFPD/psi).
Paraffin dispersant cold batch was used as an alternative treatment. To assess the effectiveness of the paraffin control treatments and their optimal application frequencies, it was necessary to use scale coupons observation, flowline pressure monitoring, and dynamometer cards analysis.
It was found that paraffin dispersant cold batch treatment resulted to be the most cost-effective way to control the problem in all of the wells evaluated and the optimal batch treatment frequency was determined for each well. Moreover, most of the wells had been treated in a very low frequency. Besides this, it was demonstrated that circulation of high volume of hot water generated production deferral.
This enabled Petrowayuu to increase its earnings in approximately 500,000 U.S. $/yr, compared with hot watering costs, mainly because of production deferral reduction.
Greater Plutonio Open Hole Gravel Pack Completions: Fluid Design and Field Application
Authors: Whaley Kevin , Price-Smith Colin , Twynam Allan , Jackson Phillip 
Published: December 2007

Abstract
Initial Open Hole Gravel Pack (OHGP) completions that have been installed in Greater Plutonio to date have all achieved complete annular packs and zero mechanical skin factors, resulting in well productivity indices that are significantly greater than expected.
The success of the Greater Plutonio OHGP completions has been attributed primarily to the rigorous design and field application of the fluid systems used at all stages of the well from drilling the reservoir through to the gravel pack itself and subsequent completion. An integrated approach was adopted for the design of the fluid systems involving extensive formation damage and fluid compatibility testing. To translate the robust design into a fluid system which can be applied effectively in the field, a thorough, fit for purpose QA/QC system for all drilling and completion fluids was developed, requiring extensive fluids testing and reporting at the well site.
The paper describes in detail the reservoir completion philosophy, drilling and completion fluids' systems and overall operational practices used in the Greater Plutonio OHGP completions. It also discusses the fluids design phase of the project and the QA/QC processes implemented in the field. Finally the paper presents the well productivity data from the wells completed to date.
Dual Lateral Horizontal Well Drilled Underbalanced in a Depleted Reservoir in Libya—Case Study
Authors: Safar Hussein , Azhary Sadek , Hijazi Ahmad , Qutob Hani , Chopty James , Pham Chau 
Published: December 2007

Abstract
The B24 well in the Fidaa Field was the first dual lateral underbalanced horizontal well drilled in Libya and the second well of Zueitina Oil Company's (ZOC) underbalanced drilling campaign.
The targeted reservoir "Facha" is partly depleted after 23 years of production to a 7.2 ppg equivalent mud weight. Nitrified diesel, a two-phase drilling fluid, was used to drill the reservoir section of the B24 underbalanced to avoid circulation losses and formation damage. Real time LWD was crucial for geosteering the well path in a complex reservoir structure and real time annular pressure measurement was also necessary to ensure the underbalanced condition was maintained throughout the entire UBD drilling phase.
Two 6" horizontal drains were drilled successfully with 2053' and 1517' drain lengths. Integrated efforts of ZOC and service companies of various disciplines during planning and operation stages of the well led to the success of the project. No QHSE incidents were reported and the productivity of the well was enhanced significantly.
The B24 well's production alone contributes to over 30% of the total Fidaa field production.