bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD Modelling of Drag Reduction Effects in Pipe Flows
Authors: Koskinen Jukka , Manninen Mikko , Pättikangas Timo , Alopaeus Ville , Keskinen Kari I. , Kolehmainen Eero 
Published: December 2007

Abstract
CFD modeling of drag reduction (DR) by polymer additives dissolving in hydrocarbon was carried out in pipe flows and in a rotating shear viscometer. Two-layer turbulence model describing the damping of turbulence by the DRA molecules in the near-wall regions was applied. The von Karman constant in the near-wall region was used as the model parameter. Extensive measurements of the DR effect for a rotating viscometer were performed at different Reynolds numbers, apparent molar masses and concentrations of DRA. The model with only one fit parameter was able to reproduce the experimental results both in pipe flows and in the rotating viscometer. Experimental results were utilized in relating the model parameter to the relevant physical properties.
Reducing Pressure Drop in Offshore Pipelines by Controlling the Viscosities of Pressurized Emulsions
Authors: Kokal Sunil , Alvarez Carlos 
Published: December 2007

Abstract
Viscosities of emulsions can be substantially higher than the viscosity of crude oil especially if the emulsion is tight. High pressure drops could develop in offshore pipeline networks due to this problem. It is shown that by adding a demulsifier offshore the viscosities of the emulsions can be reduced substantially. This paper describes the results of a study that was initiated to determine the viscosities of pressurized crude from an offshore field in Saudi Arabia. The viscosities of the emulsion were measured and determined to be very high. Several tests were conducted to determine the effect of different variables on pressurized emulsion viscosity including temperature, pressure, watercut, and demulsifier dosage. The paper presents some very interesting results for emulsions measured under pressurized conditions (for the first time). The viscosity of the emulsion can be reduced substantially by adding a demulsifier. The demulsifier breaks the emulsions into oil and water thus reducing the mixture viscosity. The results can significantly impact the transportation of crude oil from this offshore field and the required surface/subsurface facilities to produce it.
A Simple Approach to Numerical Analysis of Complex Well Tests
Authors: Al-Thawad Faisal M. , Issaka M. B. , Agyapong Dominic , Banerjee Raj 
Published: December 2007

Abstract
The inability of analytical models to handle the increasingly complex well and reservoir structures encountered in well tests has necessitated the move to numerical well testing tools. Complex well geometries, such as slanted and multilateral wells, completed across multilayered reservoirs with faults and fractures, present situations analytical models are incapable of handling.
Using a numerical well test package, we demonstrate the power of numerical solutions to overcome some of these challenges, by matching pressure transient data from complex wells completed in heterogeneous reservoirs. Three field cases are presented in this paper; a vertical well intersecting a fracture/fault network, a 45 degree slanted well intersecting a finite conductivity fracture and a dual-lateral well in a tight reservoir. An integrated approach was used to match the pressure responses in all cases.
Our experience shows that finding the optimum grid settings necessary to model the flow regimes created by these complex features, is by far the most critical factor in arriving at a satisfactory match of the well test data. Without an optimum grid, strange pressure responses can be generated, creating an artifact on both the simulated pressure and derivative plots.
An Integrated Approach to Interval Pressure Transient Test Analysis Using Analytical and Numerical Methods
Authors: Jackson R. R. , Banerjee R. , Thambynayagam R. K. M. 
Published: December 2007

Abstract
In this paper we demonstrate that reservoir parameters such as horizontal and vertical permeability's may be determined in-situ from the analysis of interval pressure transient tests, and the results verified via accurate analytical and numerical modeling and simulation coupled with gradient based history matching techniques. From evaluation of simulated and field cases, and results of numerical experiments, we propose an integrated workflow for analysing wireline formation tester interval pressure transient tests using analytical and numerical methods. This approach includes simulation model generation, reservoir simulation, interactive sensitivity analysis and an automated history matching procedure for optimisation. An objective function with appropriate weightings for different data items is defined interactively. Weighting may include prior knowledge or statistically determined error variance in input data, sensor resolution, data uncertainty and regression schemes for data sets with responses of disparate magnitude.
The MDT (Modular Dynamics Formation Tester)* tool provides the capability to conduct fluid sampling, controlled local production, standard transient and vertical interference tests. Such interval tests usually comprise of a drawdown and buildup–typically the tool is stationed in the borehole and two packers are set to hydraulically isolate a section of the formation. Observation probes or multiple probes mounted above the packers provide the capability of vertical interference testing within the near-wellbore formation.
The methodology of analysing MDT transient data is similar to conventional pressure transient tests. However, specialised mathematical models are used for matching pressure and flow rate measurements. Conventionally, analytical models have been used in analyzing these tests. While computation of analytical models are fast, they may be too simplistic or inadequate for many test configurations. On the other hand, numerical models are more realistic and flexible. However, their use is more complex. Therefore, in our interpretation methodology we profess an integrated approach.
Although gradient based techniques have been used in reservoir simulation for history matching of pressure and production performance of reservoirs for some time, our work focuses on their application to MDT interval pressure transient tests in combination with numerical well testing methods.
The Workflow for 4D Seismic
Authors: Kawar Ra'ed , Hatchell Paul , Calvert Rodney , Khan Mashuir 
Published: December 2007

Abstract
In this paper we will present the Shell workflow for 4D seismic. This workflow contains several stages: feasibility study, acquisition design, data processing, data interpretation and final feedback loop of the results to the geological and dynamic reservoir models; which in turn are used for field development planning and well proposals. Furthermore, we will also show some case studies from a variety of fields ranging from Carbonates to Sandstone and Turbidities.
The first stage of this workflow is the feasibility study that is based on measurements of rock properties and the currently used reservoir simulation model. In the case the results of the feasibility study prove to be positive we proceed to the next step. The second step involves the survey design, acquisition and in-house processing. Parallel to this process, the reservoir simulation scenarios and history matching are carried out. With these stages finished seismic data interpretation takes place. The results of the seismic data interpretation reveal the most appropriate reservoir simulation scenario. Further fine-tuning for the selected reservoir simulation and geological scenarios is then carried out to match the 4D seismic. Our experience with the fields we have processed so far has proved to find some by-passed pockets of hydrocarbons. In this paper we would therefore like to share our experience in these fields.
A Case Study on Redevelopment of a Giant Multilayered Carbonate Reservoir Based on Modification of Ongoing Water Flood Program through Integrated Reservoir Modelling Studies
Authors: Yatindra Bhushan , Amitabh Pandey , Srivastava Sanjiv K. , Lohar B. L. 
Published: December 2007

Abstract
Mumbai High North L-III reservoir is a highly heterogeneous multi-layered carbonate reservoir located on the continental shelf of Western India in Arabian Sea in about 250 ft of water depth. It is a saturated oil reservoir having about 4 billion barrels of initial oil in place and 1.7 trillion scf of initial gas cap gas in place. The field was put on production in 1976. Peripheral water injection was started in 1984. Couple of years later, up-dip water injection was also initiated in addition to peripheral water injection. The oil production rate from the reservoir peaked at about 120,000 bopd in 1986. The oil production rate in 1999 end was about 60,000 barrels of oil per day at about 60% water cut. This paper discusses various redevelopment options for the Mumbai High North L-III reservoir in detail, based on a detailed reservoir characterisation and reservoir simulation study for the field.
A 780 layer fine grid geo-cellular model was prepared taking input from core data, log data and 3D seismic. This fine layer model was up-scaled to a sixteen layer model. A full field reservoir simulation study was carried out using the sixteen layer coarse up-scaled geological model. Saturation height functions were used to distribute initial saturations in the coarse model. Layer wise pseudo relative permeability curves were generated for use in reservoir simulation.
Various redevelopemnt options studied indicate that there is a scope to improve the overall oil recovery from the multi-layered MHN L-III reservoir through infill drilling, enhancement and redistribution of water injection and proper completion strategy. A shift from line drive to pattern water injection is found to be highly beneficial.
Skills Shortage ‘The Way Forward’
Authors: Rengers Frederik , Scholten Jan 
Published: December 2007

Abstract
Concerns are raised of a personnel and skills shortage in the Oil & Gas industry.
Two solutions can mitigate the problem: 1. Make more efficient use of the present pool of people 2. Promote the Oil & Gas industry at the universities and to young professionals in other industries.
This paper will describe why there is a reason for concern and how new technology will be part of the solution to overcome a personnel shortage.
Planning, Executing and Analyzing the Productive Life of the First Six Branches Multilateral Well Drilled Underbalanced in Brazil
Authors: Lage Antonio C. V. M. , Sotomayor Gabriel P. , Vargas Angela C. , Rodrigano Roberto , da Silva Paulo R. C. , Lira Humberto L. , Filho Paulo Silva 
Published: December 2007

Abstract
The present work describes not only the main aspects related to planning and executing six multilateral (ML) horizontal branches drilled underbalanced (UB) in Carmópolis field, but also presents an analysis of the initial productive life of this well. All the main engineering information used for making decisions while planning and at well site, drilling performance and production evaluation are included.
As the targeted formations are consolidated, UBD did not bring any special concern in terms of wellbore collapse. In order to achieve the required bottomhole pressure, nitrogen was mixed with a synthetic base mud (SBM) after flowing down through the annular space between the 9 5/8″ and 7″ casings and passing through a 1″ aperture in the 7″ casing. After that, the mixture went up through the annulus between the 7″ casing and the drill string. This concentric casing approach for injecting gas made possible the use of conventional MWD, but it brought some concerns about the maintenance of the UB condition while operating.
The first ML well UB drilled in Brazil successfully combined the following different technologies: (1) ML level 2; (2) UB condition, and (3) medium radius build-up drilling system. It also involved four different parties where the operating company worked together with three service companies to build a team and achieve operational goals.
As the reservoir pressure was not sufficient to sustain the flow of oil to the surface, this paper also addresses the design of the pilot well, which was specifically prepared for operating with a sucker rod pump (SRP). Finally, from the perspective of the reservoir engineers in charge of developing this field, the oil production is presented and evaluated.
Reservoir Criteria for Selecting Underbalanced Drilling Candidates
Authors: Xiong Hongjie , Shan Dan 
Published: December 2007

Abstract
Candidate selection is the key to the success of underbalanced drilling (UBD) projects. It is a question yet to be answered why sometimes UBD significantly improves productivity compared with conventional overbalanced drilling (OBD) practices but sometimes doesn't. To answer this question, we have performed an extensive reservoir engineering study to understand the mechanisms of productivity improvement from UBD. A single-well numerical model has been built that simulates the UBD process and the OBD process (while taking into account drilling filtration invasion, mud cake, and permanent formation damage) and their impact on production under a variety of reservoir conditions. Production rates are predicted for both UBD and OBD cases. Then, an incremental net present value (NPV) model has been used to analyze the economic benefits of UBD operations (if any) for all study cases. This paper describes our study methodology, models, simulation results, and analysis results and summarizes the reservoir criteria for successful UBD operations.
Reservoir properties play the most important role in the success of UBD operations. The study clearly demonstrates that UBD works for some reservoirs but not for all reservoirs. The study results provide a set of reservoir criteria that can be used as guidelines to choose potential UBD candidates.
Drilling Near Balance and Completing Open Hole to Minimize Formation Damage in a Sour Gas Reservoir
Authors: Harting Thomas , Gent Jonny , Anderson Tim 
Published: December 2007

Abstract
Peak production of 15 MMCFD was restored in a sour well (17% H2S) drilled and completed near-
balance to prevent reservoir damage. The ACG #6B well is in the Whitney Canyon Gas Field located in southwest Wyoming. The Mission Canyon formation is the primary reservoir. The current bottom hole pressure is less than 1100 psi at 12,457 feet TVD. Severe damage occurred to the original ACG #6A wellbore and the reservoir during an attempted work-over to replace production tubing.
Recently drilled wells suffered massive lost circulation. Continued pressure depletion raised concerns that the ACG #6B sidetrack was undrillable using conventional overbalance drilling techniques. lf drilling was successful, setting and cementing production casing through the reservoir carried high risk of getting stuck. Failure to get casing to bottom would result in a poor performing well as the highly damaged rock left open hole would be unproductive.
Formation damage from the expected loss of 50,000 barrels of drilling fluid would require a fracture stimulation to regain productivity. To prevent these massive fluid losses while drilling and completing the well, the asset team considered near balance drilling and open hole completion the best option. This technique, if successful, would maximize the well productivity and eliminate casing across the reservoir, perforating, and massive acid stimulation. Drilling near balance would also significantly improve the drilling ROP and reduce nonproductive time caused by massive losses
Utilizing near-balance drilling and an open hole completion, allowed a simplified acid wash stimulation vs. a typical acid frac on offset wells. Near-balance drilling was preferred to underbalance drilling to manage the risk of produced sour gas at surface.
Production results from the well exceeded the prediction of 10 MMCFD. Current well production is in excess of 11 MMCFD and peak production rates were nearly 15 MMCFD. Minimizing formation damage provided the productivity and resulted in decreased completion costs.
Does Underbalanced Drilling Really Add Reserves?
Authors: Cade Randall , Kirvelis Ringys , Nafta Minijos , Jennings Jeffrey 
Published: December 2007

Abstract
Underbalanced drilling in its various forms has been used in the oil and gas industry for more than 20 years. A growing body of technical publications documents the mechanics and advantages of underbalanced drilling (UBD) technology, including details related to casing sizes, circulation rates, depths, rate of penetration, etc. There are also many mentions in the literature of resultant well productivity improvements. In contrast, there is little written in the literature about what contribution UBD makes to reserves and ultimate recovery.
This paper provides a basis for considering the reserve contributions of UBD technology. The six reservoir case histories presented here document tangible reserves attributable to the three key reservoir-related benefits of UBD: improved reservoir access, reduced skin damage, and better ability to evaluate the reservoir while drilling.
Underbalanced Data Acquisition: A Real-Time Paradigm
Authors: Saeed Saad 
Published: December 2007

Abstract
Formation damage and reservoir attributes can only be effectively evaluated with high quality, pertinent data. Underbalanced operations require a complex array of techniques that enable data to be effectively collated and managed. With the further advent of networking technologies the real-time transmission of this data is also now a viable option, leading to a myriad of benefits from accurate diagnosis and evaluation to real-time planning. This paper aims to describe data acquisition in underbalanced operations, commencing with a conventional acquisition setup, moving to a real-time operational case study.
Underbalanced data acquisition has its roots in the traditional well testing setup, with the basic surface separator being standard. But due to the complexity of the operation many specializations and innovative modifications have been implemented, making it an entity in itself. The paper describes a typical underbalanced data acquisition setup. It then traverses to the latest high technology realm of real-time acquisition and transmission, which enables data to be acquired in the field and transmitted directly to the client's office. System setup, architecture (client – server) and limitations will be discussed and evaluated. The advantages of real-time data acquisition will be shown as well as current caveats and possible conceptual technological innovation to overcome these limitations.
The future of underbalanced data acquisition is also taking a fundamental shift. Its amalgamation with the data analysis fields (i.e. non-simple processing) is leading to a fundamental shift in acquisition setups. These trends will be examined along with challenges and current industry direction.
In the underbalanced sphere, the marriage between data collection and transmission within a real-time framework plays a vital role in optimizing results. In the past, data acquisition design and implementation has been relegated to the last phase of many operations. This paper aims to bring data acquisition, its current direction and setup to the forefront. Formation damage and ultimately recovery are important entities, but it is only with good quality data, available in a timely manner, that these can be representatively evaluated and the well understood.
Underbalanced Horizontal Drilling Yields Significant Productivity Gains in the Hugoton Field
Authors: Devaul Tijuana , Coy Alejandro 
Published: December 2007

Abstract
The Hugoton Field located in the Texas Panhandle is one of the largest gas producing fields in the lower 48 states. Up until now, these shallow reserves have been exploited by drilling either vertical wells with air or long reach horizontal wells with conventional overbalanced techniques. Due to the low formation pressures, in the range of 600 psi, depletion is a major issue and wells drilled in conventional overbalance have not exhibited a consistent productivity trend. These low pressures have also resulted in severe lost circulation problems during drilling with resultant formation damage and productivity deterioration. An additional challenge has been the close proximity of water to the productive formation, which effectively eliminates the use of fracturing as a stimulation option.
Previously, wells were drilled vertically using underbalanced techniques (UB) but the limited kh that resulted had little positive effect on productivity. Nevertheless, the operator decided to drill three horizontal wells using UB, as a case study to make a definitive evaluation of its effectiveness in the Hugoton Field. All three wells were successfully completed and achieved a significant increase in production when compared to offset wells drilled conventionally. The results achieved were of added significance considering the low cost environment in which the wells were drilled, where use of conventional techniques typically resulted in marginal economics.
In this paper the authors will detail the well design and the UB model considerations, which took into account the geological, reservoir depletion and water proximity challenges. They will present a detailed evaluation of the incremental production rates of the order 300 – 400% that were achieved when compared to offset wells drilled and completed conventionally. They will conclude that the use of Horizontal-UB techniques in the Hugoton Field is indeed a highly viable means of achieving significant production improvement and may well provide a powerful tool for the continued exploitation and prolonged economic life of the field.
Multilayer Reservoir Model Enables More Complete Reservoir Characterization During Underbalanced Drilling
Authors: Hunt James L. , Rester Stephen 
Published: December 2007

Abstract
In order to effectively analyze reservoir inflow data from a well drilled underbalanced, a true multilayer reservoir model is required. In a previous paper,1 a single layer analytical model was developed to handle reservoir inflow resulting from the changing wellbore geometry during the underbalanced drilling process. A method to analyze data acquired during underbalanced drilling for reservoir permeability was developed and presented. The resulting reservoir model was shown to be unique in the industry. However, it was recognized that a multilayer model was needed to fully analyze the data and generate a more complete reservoir evaluation during underbalanced drilling.
This paper presents a true multilayer model that describes inflow from multiple reservoir layers encountered during underbalanced drilling. The model is fully transient and is based on the single layer model presented in previous work. The model accounts for the lengthening of the wellbore through any number of reservoir layers having similar or different properties and the resulting flow into the wellbore. Results from validation of the model are presented. The model enables formation evaluation during the underbalanced drilling process.