bluuebunny/crossref_metadata_2025 huggingface dataset:
Reservoir Management of Inflow Control Devices in an Undersaturated Reservoir: A Case Study in the De Ruyter Field, Netherlands
Authors: Leung E. , Samosir H. , Fong K. , McKellar D. , Westerhof D.
Published: February 2011

Passive inflow control devices (ICD) are being rapidly adopted in horizontal production wells particularly when there is a high probability of produced water or gas in a heterogeneous reservoir in the early life of a well. The justification, application, installation and the flow physics of ICDs available to the industry are well documented in the literature [1–3]. However, there are limited case studies that discuss the production and reservoir performance, to investigate their longer term impact supported with actual production data. The De Ruyter Field, which started production in September 2006, has been completed with passive ICDs in combination with zonal isolation in two horizontal wells in the undersaturated western fault block. This paper will describe how ICDs increased recovery compared to stand alone screens, by controlling water production and promoting inflow from lower productivity zones thus extending the life of the De Ruyter Field . This paper will also discuss the use of actual production and PLT data to history match a dynamic simulation model. The ICDs allowed the operator to commercialize an offshore development by delaying and controlling water production in a heterogeneous reservoir, thereby increasing recovery and extending the field production life.
Use of Gyro-MWD Technology Offshore, A Step Change in Drilling Performance in Saudi Aramco
Authors: Alidi Bashaar A. , Al-Sarrani Hasan F. , Stewart Jeff , Sarkar Abhijeet , Smith Geoff
Published: February 2011

Over the past few years, Saudi Aramco has had major efficiency improvements while drilling and completing smaller diameter hole sections. Such improvements provided significant reductions in rig time, and consequently reduced the overall operational cost. Less attention was paid to the upper hole sections due to less exposure to third party rental tools used in them. Offshore oil wells in Saudi Aramco have recently gone through major savings in the 28"/22" hole section after the successful utilization of the new Gyro measurement while drilling (MWD) technology coupled with powerful, performance drilling mud motors.

The normal process was to drill the 22" hole section, 1,050 ft +/−, running Gyro single-shot surveys every 50 ft - 100 ft drilled, until the well is drilled in a safe path away from other wells within its vicinity. After adopting the Gyro-MWD system, along with a modified 22" bit and 111/4" performance mud motor, the rate of penetration (ROP) increased by 82%; Thus, reducing CPF respectively.

The increase in the ROP resulted in average savings of 0.9 days per well (6 to 12 wells per platform) at this stage of the well. In addition, the reliability of the gyro tool face from vertical, even when inside the casing, provided confidence in drilling operations, which facilitated the increase of weight on bit (WOB), leading to faster drilling, thereby improving the overall ROP. Furthermore, eliminating the use of wireline to run surveys increased the safety of the operation.

The success of these 22" hole sections was substantial across the board, since it was one of the challenging areas where major improvements had not taken place before for years.

This paper will evaluate the new drilling practice in more detail. It will also cover the conventional drilling and operational practices, and the thorough planning stages that resulted in these fruitful savings.
An EoS Model for a Middle East Reservoir Fluid with an Extensive EOR PVT Data Material
Authors: Negahban Shahin , Pedersen Karen Schou , Baisoni Mahmoud Ali , Sah Pashupati , Malaysia Calsep , Azeem Jawad
Published: February 2011

The paper presents compositional data and PVT data for a Middle East reservoir fluid with a reservoir temperature of 394 K and reservoir pressure of 287 bar. The PVT data was selected and designed to provide the best possible starting point for developing an EOS model that would accurately reproduce the phase behavior of a reservoir fluid subject to injection of either CO2 or a hydrocarbon gas.

To eliminate the uncertainty from use of default molecular weights and densities for the C7+ hydrocarbon fractions the reservoir fluid composition was analyzed using a True Boiling Point (TBP) analysis. PVT experiments, both routine and gas injection (EOR) experiments, were carried out including solubility swelling, equilibrium and multi contact experiments and slim tube tests. With both injection gases the reservoir fluid shows a combined vaporizing/condensing drive mechanism.

A 9-component EOS model was developed for the volume corrected Peng-Robinson equation of state, which shows a good match of all available data. Two methods were used to predict the vaporizing/condensing MMP; (a) a multi-component tie-line MMP algorithm and (b) a compositional 1D simulator. The CO2 MMP is considerably lower than the reservoir pressure while the MMP seen with the hydrocarbon gas is close to the reservoir pressure.
Case History of a Successful Progressing Cavity Pump Application in an Extremely Low Pressure Environment
Authors: Lewis Blain , Daves Dusty , Skelton Gregg
Published: February 2011

This paper summarizes the production history, wellbore configuration, reservoir parameters and mechanical design parameters of a progressing cavity pump application in a high productivity, extremely underpressured, partial water drive reservoir. The current reservoir pressure of approximately 50 psi has presented a unique challenge to optimizing the productivity and operating costs of the well. It was operated for many years on conventional rod pump with a history of downhole equipment failures and restricted production capability. An effort to produce the well with an electric submersible pump system was unsuccessful because of the low reservoir pressure and the limited vertical space to install equipment. A progressing cavity pumping system has been in operation for fifteen months. After seven subsurface failures in six months, several changes to the system were made that optimized the production rate and minimized downhole failures. Among these changes were installing plastic coated sucker rods, an oversized carburized rotor, and a tubing anchor and stabilizing the wellhead from vibration. The oil production rate on progressing cavity pump has increased 35 BOPD, almost 300%.
How Smart Completion Can Maximize Oil Production and Recovery Factor in Stacked-Marginal Reservoir
Authors: Naroso Gangsar , Hofland John
Published: February 2011

This paper will address how reservoir depletion using Smart Well completions in stacked-marginal reservoirs will gain large benefits. Different scenarios will be used to illustrate this point.

Utilizing On-Off ICV’s combined with Permanent Down Hole Gauges, will achieve an optimized off take from each zone, thus creating efficient reservoir depletion as well as maintaining sustainable oil production. A cycling production approach from different zones will optimize well production; optimizing reservoir drainage and improve recovery factor.

Marginal reserves are hydrocarbon accumulations too small or too difficult to recover economically by themselves under prevailing fiscal terms. Stacked reservoirs containing marginal reserves are often passed over in favor of more prolific zones containing economic volumes. The opportunity to develop the marginal reserves in conjunction with other marginal reserves or with larger reserves by commingling (and by doing so make them economic) is sometimes overlooked by operators due to government regulations prohibiting commingling.

Shanayel field has stacked-marginal reservoirs that will benefit from the smart well approach. As part of Shanayel field development plan and reservoir characterization study, an observer well will be worked over and will be completed in 5 (five) zones. The smart completion configuration include 5 ea of 7 inch Feed through Hydraulic set - Retrievable packer, 3.5 inch Hydraulic ON-OFF ICV, 4 ea of 3.5 inch Single Gauge Carrier with P & T reading ported to annulus, 1 ea of 3.5 inch Dual Gauge Carrier with P& T reading ported to annulus - tubing, 3-1/2 inch - 9.2 ppf CRA tubing and 7 inch - 5 Penetrations Wellhead.

An automated Digital Infrastructure system is planned to operate the Smart Well completion, which enables to manipulate ICV’s remotely and monitor PDHG by providing connectivity to the existing field control system.

Deployment of the smart completion will provide proactive approach to manage oil production at every zone in the well, thus form efficient reservoir depletion as well as maintaining sustainable oil production. Pressure monitoring in every zone provides sufficient data to determine the depletion strategy, which in turn will maximize production and increase recovery factor. The well will also provide operational experience, as it will demonstrate if this is a viable completion technique for small and stacked hydrocarbon accumulations. Lastly, the initiative fits into ADCO’s 2020 vision.
High and Low Frequency Vibrations in Flare, Piping Systems: Causes, Consequences, and Avoidance Screening Methodology
Authors: Moustafa Ihab Fikry
Published: February 2011

Designing a new flare system or evaluating the integrity of an existing one has become a more complicated practice in the last few years. The original design of the flare system was probably based on a simple static analysis and code compliance, and didn’t consider the different types of vibration sources that will affect the integrity of the flare system in the short or the long term, these was not obvious to the designer, especially as most piping design codes don’t address vibration in a meaningful way.

Recently, incidents have occurred world wide where piping failure was related to unexpected piping vibration, this typically occurred due to increased fluid flow as a result of de-bottlenecking and the relaxation of erosion velocity limits. There also was a tendency by designers to use thin walled pipe for economic reasons and to allow increased flexibility in the piping system. This is very common on lower pressure designed relief and flare systems.

This paper will consolidate the guideline, techniques, definitions and equations related to High and Low Frequency Vibrations in Flare Piping System to get better understanding of the nature of these vibrations, I will also describe how to build a screening tool and provide examples from two Egyptian gas plants to see practically how the screening assessment was completed.
Improving Progressing Cavity Pump Performance Through Automation and Surveillance
Authors: Woolsey K. A.
Published: February 2011

To extend the run life of the pump while producing all available fluid is the goal of all PCP operators. The primary challenge is to do so without starving the pump and causing damage to the stator. The petroleum industry has been searching for years to find a reliable way to control progressing cavity pumps for pump-off. Several methods have been used, from monitoring torque to manual fluid levels. To date, none of these have been commercially successful. A method for controlling these wells has been developed combining wedge meter flow technology and microprocessor control of both electric motors using variable frequency drives and hydraulic motors using proportional control valves. This method has proven to be accurate and reliable, extending the run life while producing all available fluids.

Combining this automated technology at the well with a web based system that feeds back real time data to a dedicated SCADA host allows PCP technical experts to diagnose problems, and operators to respond quickly to changing well conditions.

This presentation discusses the advances in automation and optimization of progressing cavity pumps. The method will be explained and data will be presented of field study results showing actual well tests.
Integration of Montney Microseismic Information Into a Reservoir Simulator to Analyze a Horizontal Wellbore With Multiple Fracture Stages
Authors: Quirk D. J. , Cui A.
Published: February 2011

In order to get a clear picture of the effectiveness of a multi-stage stimulation treatment pumped into the horizontal wellbore of a tight gas reservoir, one must integrate data from a number of different sources. This will provide a more complete forecast of the reservoir's development.

The Montney formation straddles the British Columbia / Alberta border in the Western Canadian Sedimentary Basin. There is significant variability in the formation's properties across its area, but even so, we have seen a multitude of horizontal wellbores lined up within the formation in recent years. Many involved have questions about fracture spacing along a horizontal wellbore, and ultimately, the spacing of the horizontal wells in a field. The answers to these questions can lead to improved recovery factors and better economics for the resource play.

In this case study, seven stages of Basal Doig / Upper Montney microseismic data are integrated with fracture pumping information, and finally incorporated into a reservoir simulator. Two years of production history from the Montney horizontal is matched to "calibrate" the four layer reservoir model and make it a predictive tool. This provides the basis for understanding of drainage radiuses around the fractures, and for recommendations on fracture spacing in order to optimize completions in subsequent wells.

The calibrated reservoir model is then used as a predictive tool to understand drainage radius and productivity differences when the number of fracture stages in the wellbore is increased to reduce fracture spacing. Predictably, the cumulative production from the tight gas well with more stages is greater than the same well with fewer stages. Ultimately, there is an economic trade-off between completing the well with more stages and increased well productivity, and an optimal combination that differs from one region to the next.
An Innovative PCP Logging Technique for the Separated Layer Production Wells
Authors: He Liu , Fengshan Wang , Guochen Shi , Gang Cao , Tao Jiang , Tianli Zhang
Published: February 2011

In the past 50 years, the oil production of Daqing Oilfield has maintained 50 million tons (near 350 million bbls) per year for 27 years. To date, Daqing Oilfield is still the largest continental oilfield in China. Separated layer development technology is one of the key techniques contributed to this great achievement. In order to monitor dynamic performance of separated layer production, it was necessary to implement logging technique periodically in a large number of selected injectors and producers. Due to the limit of annulus size is too small for sensor to be run into down hole of progressing cavity pump (PCP) wells, traditional PCP system design couldn’t meet the requirement of well logging for separated layer production.

Since separate layer development technology is more and more popular in oilfield development, PCP logging technique has become a bottleneck issue which limited PCP application in larger scale. This paper presented an innovative design for logging technique in PCP wells. In this design, a unique drive head design was developed as well as several special downhole tools which applied the path for sensor and wire to be run into the appointed place.

Till the end of 2009, this technique has been applied in more than 200 PCP wells in Daqing Oilfield. The operation was simple and safety, the successful ratio was 95%. This technique could also be applied in other conditions which has a brilliant future.
Analysis and Flow Modeling of Single Well MicroPilot to Evaluate the Performance of Chemical EOR Agents
Authors: Cherukupalli Pradeep , Horstman Dirk , Arora Shyam , Ayan Cosan , Cig Koksal , Kristensen Morten , Ramamoorthy Raghu , Zaggas John , Edwards John
Published: February 2011

Many Enhanced Oil Recovery (EOR) applications involve injection of fluids into oil reservoirs to displace and recover as much of the remaining oil as possible. Typical maturation of (chemical) EOR involves phase and compatibility testing in the laboratory, displacement experiments in cores before single or multi-well pilot trials in the field, leading eventually to full field implementation. Recently, a new technique referred to as MicroPilot* has been introduced as an intermediate step to take laboratory results into the field, providing valuable data for pilot design and implementation.

The MicroPilot* is a log-inject-log method executed under in-situ conditions downhole in a matter of hours. A suite of wireline openhole logs are utilized to determine the initial saturations. The test then continues with a formation tester string which can drill into open hole, cleanup and inject an EOR agent into the formation. Following injection, the suite of open hole logs are run again to evaluate the effectiveness of the flood by measuring the change in oil saturation and the dimensions of the flood.

The world’s first successful test has been run in a medium heavy-oil field in the Sultanate of Oman with Alkaline Surfactant Polymer (ASP) solution as the EOR agent. Post-injection formation image logs clearly show the swept zone and an oil bank.

In this paper we take the analysis of the test a step further and present dynamic simulation modeling results using the acquired data as benchmark parameters for the history match. Grid verification using single-phase pressure transient analysis is discussed. Each phase of the test is modeled and history-matched to the acquired data. The electrical borehole image log response is matched together with the vertical saturation profile seen on the post injection NMR log. During the history match, formation parameters are fine tuned and some parameters describing the EOR displacement process in the simulator are studied in more detail. The history matching effort not only provided a consistency check for the field observed data but can also help determine a few key modeling parameters prior to possible field pilot planning.
The Role of Corrosion Prediction and Real-Time Corrosion Measurement Technologies in Corrosion Management – Theory and Applications
Authors: Kelleher Andrew
Published: February 2011

The methods and tools used to mitigate risks associated with corrosion damage have continuously evolved in response to an increasingly competitive marketplace and the realities of ageing plants. The development trend is clear: systematic approaches supported by both traditional and new technologies. Bayer Technology Services GmbH has recognized the need for a multi-disciplined team to assist companies to establish a robust Corrosion Management System (CMS) and to leverage new technologies in the management of corrosion risks.

Corrosion prediction and real-time corrosion measurement technologies are inherently suitable for application within the CMS. The high quality corrosion information provided by these technologies facilitates an increased level of understanding (and hence control) of the corrosion system. In contrast to traditional technologies, the corrosion prediction and real-time corrosion measurement technologies promote and support continual improvement in Corrosion Management.
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

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

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

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

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

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

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

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

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

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

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

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

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.
Effect of Sulfur Deposition on Rock Permeability in Sour Gas Reservoir
Authors: Xiao Guo , Zhimin Du , Li Wang
Published: February 2011

Reduction in pressure and temperature generally reduces the solubility of sulfur in sour gas reservoir. Once the reservoir fluid has reached a sulfur-saturated state, further reduction in pressure and temperature will cause sulfur to deposit. Sulfur deposition in the formation, induced by a reduction in the solubility of the sulfur in the gas phase, may significantly reduce the inflow performance of sour gas wells and even wells have become completely plugged with sulfur in sour gas reservoir within several months. In this paper, effect of sulfur deposition on reservoir permeability in sour gas reservoir was investigated from a laboratory perspective. A series of displacement experiments were conducted using gas sample with H2S mole concentration of 14.99% and 24.69%, rock sample of permeability of 1.37, 3.6 and 46.5 millidarcy, different flow rates of 3.25 and 12.5cc/min, and average pore throat size in the range of 0.1 to 1.0 um. Experimental results indicated that the higher of hydrogen sulfide concentration have a severe effect on sulfur deposition and subsequently the rock permeability decreased rapidly. When element sulfur grain size is more than average pore throat size, rock permeability changed strongly. Through a regression analysis, variation of rock permeability (K vs. P) was linear relation under high pressure, while approximate exponential function under low pressure. This work will help engineers evaluate accurately well deliverability in sour gas reservoir.
Application of Innovative Ceramic Centralizer for Solid Expandable Liner
Authors: Zhou Shaohua , Kamal Mansoor , Sanders Tom
Published: February 2011

Traditionally, solid expandable liners have been run without any centralizers due to the perceived risk involved, since typical centralizers would impose extra restrictions on the pipe body, which would require additional force to expand. Also, the centralizers may break during running in hole, which would lead to a possible stuck liner, and consequently, be a major problem of liner expansion. It’s also important to realize that there is a limited running clearance if conventional centralizers are utilized. This puts a lot of constraints on the type and availability of possible centralizers. As a result, some residual mud may remain on the low side of the hole during cementing operations, since it is not possible to rotate the expandable liner while cementing, nor reciprocate the liner after reaching setting depth to avoid possible damage of the expandable casing’s connection protection sleeves across the prevous 7 in. casing shoe or window exit. Consequently, the cement bond between the expanded casing and the formation would be limited and long-term isolation may be less than required.

Recently, an innovative ceramic centralizer was evaluated and implemented in the field. The ceramic centralizer consists of three individual pads affixed to the expandable casing 120 degrees offset to each other, with three centralizers equally spaced out along the middle part of the 38 ft expandable casing joint. The pad itself is made of carbon fiber ceramic composite material that is characterized by strong toughness. Once bonded to the base pipe it is not possible to remove it even with 180,000 lbs of force. It has a lower friction factor than casing, and is corrosion resistant. After tailoring the pad design to suit a 5½ in. expandable liner, such centralizers on cemented expandable liners were successfully run in five wells without any problem. The acquired ultrasonic image tool (USIT) log demonstrated that the cement bond with such centralizers was substantially better than the case without the use of any centralization.