bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seismic to Simulation Fracture Characterization of a Green Carbonate Reservoir in Presence of Large Uncertainties
Authors: Astratti D. , Souche L. , Faskhoodi M. M. , Menegatti P. 
Published: February 2011

Abstract
This Middle East case study addresses the modeling of a green carbonate reservoir which production is controlled by fractures.
The workflow integrates 3D seismic, cores, logs and production data to assess and minimize the production forecast uncertainties.
The 3D seismic was used both for the characterization of layer-bound fractures, by means of fracture-related attributes, and to locate sub-seismic faults and associated fracture corridors. The extraction of seismic lineaments was performed using edge-enhancing and automated interpretation techniques. A simple approach was introduced to identify the most persistent lineaments and increase the confidence in their structural nature.
The distribution and properties of small scale fractures was constrained by a combination of image logs, cores, drilling logs, seismic attributes and petrophysical model. Outside the corridors, the vertical variability of the fracture density was derived from the interpretation of electrical images, whereas its lateral variations could be correlated to petrophysical changes. Two consistent sets of orientations could be identified from image logs, while a detailed comparison between seismic attributes and flowing fractures from well data showed that the most open fractures were located in the vicinity of the faults.
Multi-point statistics (MPS) were then used to constrain the location of the most effective fractured zones while retaining spatial consistency and maximum accuracy at the well locations. The final discrete fracture network (DFN) honored all measurements and computed trends and was upscaled to effective fracture properties (porosity, permeability and shape factor) in the reservoir grid.
A dual porosity simulation model was generated and the fracture properties were calibrated against dynamic data. The mismatch between observed and simulated dynamic data was ascribed to the uncertainty in the input to the DFN modeling process. To avoid local modifications while preserving the original fracture property distribution and contrast in the model, history matching was performed by iteratively conditioning fracture intensity to dynamic data and subsequently recomputing the effective fracture properties based on the new modified fracture intensity distribution.
A Holistic Solution for Compact Oil Treatment Separation Systems
Authors: Chiesa M. , Hamid W. 
Published: February 2011

Abstract
The present contribution presents the main achievments of Hamworthy R&D effort in developing a holistic solution for compact separation. A main drive of this development consists in incorporating robust electrostatic coalescers into three phase separators. Our solution enables single-stage separation and accelerates separation of oil and water. The most recent product developed to enable single-stage separation is the VIEC-LW (Vessel Internal Electrostatic Coalescer – Low Water). The VIEC-LW is an electrostatic coalescer element and it is used to enhance and accelerate the separation in a three phase separator. It is designed to remove the small droplets of water remaining after bulk separation is achieved. VIEC-LW is installed downstream of the bulk speparation device, the VIEC (Vessel Internal Electrostatic Coalescer). We present the perfromane of the combination the VIEC and VIEC-LW on several different real crude oils ranging from API 17 to API 29. For the API 29 crude, the water in oil (WiO) content was reduced below 0.5% without any use of chemicals. For the challenging API 17 oil, the oil in water (OiW) was reduced to below 2–5%. All the test results yield good separation even with tough separation conditions i.e stable emulsions with extremely small droplets. The produced water leaving the separator contained 2 to 200 ppm oil in water.
Comparative Study of Novel Population-Based Optimization Algorithms for History Matching and Uncertainty Quantification: PUNQ-S3 Revisited
Authors: Hajizadeh Yasin , Christie Mike , Demyanov Vasily 
Published: February 2011

Abstract
In modern field management practices, there are two important steps that shed light on a multimillion dollar investment. The first step is history matching where simulation model is conditioned to production and/or seismic data. In this inverse problem, we calibrate our model to reproduce the historical observations from the field. In second step we quantify uncertainty of the predictions made by calibrated models. These two steps are tied together; multiple history matched models are essential for a realistic uncertainty estimate of the future field behavior.
Stochastic population-based optimization methods have been used in the last two decades as popular tools in history matching frameworks. Stochastic sampling algorithms explore/exploit the parameter space to find diverse good-fitting models. Recently two innovative algorithms were proposed to tackle history matching problem; ant colony optimization [Hajizadeh et al. 2009] and differential evolution [Hajizadeh et al. 2010]. However these algorithms were applied for history matching of a simple reservoir model with few unknown parameters. The question is the capability of these new methods for solving complex history matching problems and estimation of the uncertainty associated with these models.
This paper compares the application of ant colony, differential evolution and neighbourhood algorithms for history matching and uncertainty quantification of the PUNQ-S3 reservoir. PUNQ-S3 model is a synthetic benchmark case with challenging parameterization, history matching and uncertainty quantification steps. We compare performance of the above algorithms in sampling the parameter space and obtaining multiple history-matched models. The paper also includes comparison of convergence properties of these algorithms for this high dimensional problem. We show that novel stochastic population-based optimization algorithms can be successfully applied for history matching problems with large number of unknown parameters. The algorithms are integrated with a Bayesian framework to quantify uncertainty of the predictions. Results confirm that the proposed methodology provides reliable predictions of the future reservoir recovery.
Laboratory Studies at Reservoir Conditions on the Impact of Acid Gas and CO2 Displacements on the Carbonate Matrix
Authors: Obeida Tawfiq , Kalam Zubair , Al-Sahn Hani , Gibson Adrian , Masalmeh Shehadeh , Zhang Hongmei 
Published: February 2011

ABSTRACT
Laboratory studies have been performed to evaluate the impact of acid gas (80% H2S, 20% CO2) and CO2 injection on the carbonate matrix properties at reservoir conditions. Injectivity abnormalities have been reported in the literature in several WAG projects involving CO2 and loss of injectivity has been crucial factor in many of these projects. However, literature data shows that some reservoirs loose injectivity and others increase injectivity after the first CO2 slug is injected. Change in rock properties due to fluid/rock interaction can account for some of the injectivity loss.
In this paper we will report on recent laboratory study that was conducted using limestone and dolomite reservoir core samples from a carbonate reservoir in Abu Dhabi. The laboratory program used core plugs, or plug composites, that had been aged with reservoir oil at a representative initial water saturation prior to the gas displacement. The displacements were performed with three fluids: Vapor phase CO2Acid gas (80% H2S, 20% CO2)Brine saturated with CO2
The vapor phase CO2 and acid gas displacements were considered to be typical of those found near a gas injector, whereas the brine saturated with CO2 displacement was more representative of the reservoir away from the well bore or found during a WAG process. The displacements were conducted at a series of increasing rates. After 75 pore volumes the plug was left to soak for 48 hours in the displacing fluid. Two further displacements were then performed. Following the displacement tests, an assessment of damage to the core plug was made by measuring the porosity, permeability, SEM, XRD, MICP and taking thin sections of the core plug. This paper also presents laboratory work to study CO2 solubility in different brine salinities up to 250 K ppm at different reservoir temperatures up to 149 C and pressures up to 400 bar. A CO2 solubility model is proposed to calculate solubilities at representative salinity and previlent pressures and temperatures.
The preliminary results show that in most of the experiments no significant change in permeability was observed. However, in some experiments both enhancement and decrease in permeability was reported. The results of this ongoing study will strongly impact the planning of EOR development options. Injection of CO2 or acid gas will be significantly hampered if the gas injection results in matrix plugging or core damage, and needs to be appropriately evaluated for the reservoir under consideration.
Optimizing The Planning, Design And Drilling Of Extended Reach And Complex Wells
Authors: Agbaji Armstrong Lee 
Published: February 2011

Abstract
Extended Reach Drilling (ERD) is an integrated methodology for drilling high-angle wellbores with long horizontal displacements. Several problems are associated with extended reach wells. Thus for high levels of performance improvement to be achieved, it is essential to analyze the interrelationship among the elements involved in the entire drilling process. This is because a system that considers the individual elements of the drilling system in isolation is inadequate to deliver desired performance improvement.
In this study, an algorithm that sets forth a design for a drilling program that is suitable to drill an extended reach well was developed using Visual Basic. Although the algorithm touches on several factors affecting extended reach drilling, the major focus is on the six elements, which are considered the critical factors. These are: Well Trajectory Design, Bottom Hole Assembly (BHA) Design, Bit Hydraulics, Drill String Design, Torque and Drag, Hole Cleaning and ECD Management. The proposed algorithm evaluates the interrelationship among these critical factors and provides direction on the processes and tasks required at all stages in the design and drilling of an ERD well to achieve maximum drilling performance. The development of the model is based upon information gathered from several sources, many new ideas from technical publications, along with information and feedback from field-based personnel. The output generated from the model compare well with results from actual field data.
Performance Analysis and Field Application Result of Polymer Flooding in Low-Permeability Reservoirs in Daqing Oilfield
Authors: Fenglan W. , Xia L , Siyuan L. , Peihui H. , Wenting G. , Yonghui Y. 
Published: February 2011

Abstract
The polymer flooding technology in high and medium permeability reservoirs has been applied commercially in Daqing Olifield since 1996. It has become an important supporting technology for both the stable output of Daqing Oilfield and the development improvement of the mature oilfields. In order to study EOR method in low permeability(less than 100mD) reservoirs, pilot tests of polymer flooding were performed in Daqing oilfield. According to the research results, the low-molecular weight polymer (400800 Dalton) can be continuously injected into low permeability reservoirs under the specified well spacing. Pilot tests of polymer flooding show that oil production was increased from 1.06 tons/d to 3.04 tons/d and water cut was decreased from 96.0% to 89.8% in low permeability reservoirs. Formations with extra-low permeability(less than 10mD) are not flooded effectively in the process of polymer flooding. Production performance of polymer flooding in low permeability reservoirs can be improved by measures of fracturing or separate zone injection with different molecular weight polymers. Comparison and analysis on injection profiles and productivity profiles at different injection polymer parameters showed that the polymer solution with low-molecular weight and relative high concentration was suitable for polymer flooding in low permeability reservoirs. Numerical simulation and pilot results both showed that more than 5% OOIP were obtained by polymer flooding over that of water flooding in low permeability reservoirs in Daqing oilfield.
Advances in Maintenance Turnaround Management
Authors: Al-Haider Adnan 
Published: February 2011

Abstract
An advance in Maintenance Turnaround Management has been recently implemented successfully in Kuwait Oil Company (KOC), Kuwait since April 2009.
The purpose to adopt this strategy for KOC was based on lessons learned, Reliability Centered Maintenance (RCM) and Risk Based Inspection (RBI) in order to optimize operation, maintenance and inspection resources and increase availability of production facility, improve KOC production capacity in addition to minimizing shutdown time.
The philosophy for its Planned Maintenance / Predictive Maintenance activities were evaluated and upgraded based on two major concepts of Risk Based Inspection (RBI) and Reliability Centered Maintenance (RCM). Both assisted KOC to improve Turn around Preventive Maintenance duration phenomenally to become three weeks instead of four weeks.
The Risk Based Inspection (RBI) approach was developed by Inspection and Corrosion Team of KOC in order to mainly handle the stationery equipment like pressure vessels, heat exchangers, piping etc.
Due to this concept, Major Survey activity will be carried out once in eight years instead of four years which is being practiced now.
Also, Minor Survey which used to be carried out every two years will be totally eliminated based on the following findings/concepts: Past experience revealed that there are no significant defects on Relief valves while testing every two years.Cross over KOC we noticed that purchasing of 300 PSV’s valves will be sufficient to cater for 50% of PRV in GC’s.Twinning of Relief valves system which will have a two relief valves on each system with independent isolation facility to overcome Shut down and to enable replacement of each valve independently.
On the other hand Reliability Centered Maintenance (RCM) approach is being developed by Maintenance Support & Reliability Team which is proven to be a methodology of analyzing assets and structuring the appropriate predictive and preventive maintenance tasks warranted by the assets criticality and failure modes/affects for rotating equipment.
The approach is defined mainly on criticality where: Planned Maintenance is carried out for highly critical equipment.Predictive Maintenance is carried out for the less critical equipment.Break down maintenance for the least critical equipment.
Selecting Economical Viable Project Using the Effective Profit Indices and Investment Margin Concept
Authors: Biu Victor T. , Biu Emmanuel O. , Buduka Stanley , Wachuku Prince , Ajienka Joseph 
Published: February 2011

Abstract
Conventional profit indicators NPV, P/I, ROR and PBP are prefer by economist, business analyst, engineers and even the academia for identifying economically viable projects where comparative and critical investments decisions are to be taken. Though sometimes considered as quick look, major investment in the oil and gas industry have rely on the analysis and interpretation of these profit indices before final investments are made. However these interpretations can be misleading where there is changing cash flows with different discount rates resulting in different recommendations; thereby increasing risk and uncertainties inherent in each project.
This paper introduces the effective profit index EPI and depleting profit index DPI which examine the limitation of P/I, NPV, ROR, PBP and integrate it into a robust model to understand and identify progressive profit index with time for improved decision making.
Results indicate DPI exhibit similar interpretation with the GRR and often times with any of the profit indices such as P/I and NPV as seen in both cases review. Also in case 1, the project with initial high EPI such as P and Q with higher IRR are overtaken with time, thus suitable for making investment decision when IRR is uncertain and also visualized the progressive profit margin with time.
Thermodynamics Prediction of Wax Precipitation Using the Patel-Teja Equation of State
Authors: Farayola K. K. , Adeboye Y. B. , Adekomaya O. A. , Olatunde A. O. 
Published: February 2011

Abstract
Flow assurance is a problem which plagues the petroleum industry. The purpose of this study is to predict wax precipitation in crude oil pipelines. The industry spends millions of dollars to remediate this problem. As a result, ways are being sought to reduce the occurrence of the phenomenon by predicting as accurately as possible, the wax appearance temperature, which is a very important parameter when analysing the problem of wax precipitation. Experimental methods have been employed in times past, but in recent times, thermodynamic modeling of wax formation allows better prediction of wax deposition in pipelines. A three parameter equation of state, the Patel-Teja EOS is used to describe the non-ideality of the liquid phase (oil) while the UNIQUAC model is used to describe the solid phase (wax). Solid precipitation is measured as temperature drops below the wax appearance temperature. The introduction of the third parameter increases the accuracy of results. The results from this study are in agreement with observations made by Pedersen et al. (1995) and Lira Galeana et al. (1996). This study has shown that the Patel-Teja EOS gives better predictions of wax precipitation when compared with the Peng Robinson EOS. This paper is based on theoretical data only. Accurate prediction of wax precipitation reduces loss time, maintenance cost and production loss due to shut-in. Although a kinetic model is required to estimate the wax deposition rate, accurate thermodynamics model is a key requirement for both wax deposition and precipitation calculations as the kinetics is being controlled by the thermodynamics driving force. The thermodynamic model proves successful and compares favourably with results obtained from the experimental data.
Evaluation of Compressibility Factor Correlations for Niger Delta Gas Reservoirs
Authors: Festus Olajide Olateju , Ikiensikimama Sunday Sunday 
Published: February 2011

Abstract
This paper presents evaluation of compressibility factor correlations for the Niger Delta gas reservoirs. The correlations were evaluated using three principal methods. First, the use of statistical analysis - mean relative error, mean absolute error, standard deviation of the mean relative error and absolute error as well as the coefficient of correlation were computed. Secondly, these statistical parameters were combined into a single parameter called rank using the Multiple Statistical Optimization Model (MULSOM). Finally, performance plots of the experimental and estimated values of the compressibility factors were made to serve as a confirmation of the results of the statistical and ranking methods. The database consists of 513 data points obtained from Niger Delta gas reservoirs. The Z-factors evaluated are in the ranges of reduced temperature and pressure of 0.5796≤Tr≤1.758 and 0.410≤Pr≤8.985 respectively. The Carr-Kobayashi-Burrows correction for the presence of CO2 and N2 was used. The best correlation for the Niger Delta natural gas is Brill and Beggs. It has a rank of 2.82, a percentage absolute error (Ea) of 3.234 and the best performance plot. Brill and Beggs is recommended to be used in situations where laboratory PVT data of natural gas compressibility factor is not available for the Niger Delta gas reservoirs as well as other regions of the world where the gas composition is similar to that of the Niger Delta.
Mathematical Modelling of the Effects of In-Situ Stress Regime on Fracture-Matrix Flow Partitioning in Fractured Reservoirs
Authors: Oluyemi G. F. , Ola O. 
Published: February 2011

Abstract
In fractured reservoirs, there is a high tendency for flowing fluid to partition into fracture and matrix flows depending on the hydraulic and lithological properties of the two sub systems. Flow partitioning in this type of reservoir is complex and its understanding is still limited. However the understanding of this phenomenon is very crucial for the design, optimisation and implementation of production and chemical placement operations in such reservoirs.
One of the several factors responsible for the complexity inherent in flow partitioning and which makes its understanding difficult is the effect of the in-situ stress regime. In this work, we model the effect of stress regime on flow partitioning in a fractured reservoir. In the modelling work, we use the theoretical well radial model and Forchheimer model for turbulence flow to obtain a model for flow partitioning, which we then couple to a stress model. The modelling work has provided an enhanced understanding of flow partitioning and the possible effects of stress regime on its behaviour and pattern.
Application of Fiber Bragg Grating Sensor Networks in Oil Wells
Authors: Pan Y. , Chen Z. , Xiao L. , Zhang Y. , Fu J. 
Published: February 2011

Abstract
As the fiber Bragg grating (FBG) sensors, with a high credibility, high temperature resistance, corrosion-resistant, and anti-electromagnetic interference, are suitable for working in a harsh environment of oil and gas wells, we develop a FBG wireless sensor network to monitor the temperature and pressure of the reservoir formation. A data acquisition module is set up at wellhead to demodulate the analog signals into digital signals. Another data transmission module installed at wellhead can send data from the data acquisiton module through a RS-232 interface to dadabase by a GPRS wireless mobile communication network. The user can browse the real-time published data through internet.
We build an experimental apparatus to simulate high temperature and high pressure of the downhole environment. We put a FBG sensor into the apparatus, increase the temperature and pressure gradually, and then reduce them back. The data acquisition module and data transmission module succeeded in their roles. In addition, we determined the extremes of the FBG sensor on temperature and pressure.
Through repeating the above operation a couple of times, we obtained a satisfactory match between the input values and measured values. Our system can measure the deferent depth temperature and pressure of the formation in real time. It has many properties: responsivity, accuracy, a high speed transmission rate, and a low bit error rate. In addition, it can work for 24 hours and 7 days a week in all weather.
To real-time monitor the temperature and pressure of the formation, the system can provide more reliable bases to engineers to predict and solve production problems. It has important practical significance particularly for outlying remote areas and offshore oil production. The application of this technology will effectively reduce the production of human errors and labor costs. Moreover, it will benefit the statistical analysis of massive data that require a unified management and sharing.