bluuebunny/crossref_metadata_2025 huggingface dataset:
Reducing Uncertainty and Costs in Drilling and Completion: Innovative Underreamer Verifies Wellbore Diameter in Real-Time
Authors: Rasheed Wajid , Zhou Shaohua , Jones David
Published: March 2009

Applications such as close tolerance casing design and expandable liners, often necessary for deepwater and subsalt well construction, require underreaming to ensure adequate reservoir diameters. However, underreaming generates uncertainty sometimes, particularly in hard formations. Instead of direct real-time verification, reliance is placed on indirect indicators such as increased standpipe pressure or drilling torque. The uncertainty as to whether the desired wellbore-diameter is actually delivered exists until a calliper is run. Subsequently, a correction run may still be needed, hence additional cost.

This paper explains a design process to solve these problems. An explanation of a novel technology illustrates how it verifies and detects variations in underreaming diameter in real-time. A telemetry system alerts the user if there is a significant difference between planned and actual diameters and prompts a check of operational parameters such as WOB, drilling fluid pump rates or RPM, if needed, repeat underreaming in the uncertain interval.

A comparative evaluation was made of the drilling dynamics of underreamers and the root cause analysis of NPT. For example, bit only RoPs are higher than underreaming RoPs and in a combination BHA the bit tends to out-drill the underreamer. Not only does the underreaming have limited cutter contact with the wellbore and limited hydraulics, BHA modelling shows these limitations are worsened by wall-side forces and bending moments which are concentrated at the underreamer.

The design process sought to improve traditional technology by considering RoP, improved underreaming BHA stability and generate a more balanced cutting action. CFD (Computational fluid dynamics) show how a novel configuration of nozzle distances and orientations improves cuttings evacuation and reduces particle residence times.

In conclusion, a drilling engineering risk table presents 20 underreaming applications and is used as a benchmark for a comparative evaluation of underreaming risk types.
The Challenges of Designing and Installing High Pressure Gas Pipelines Through Inshore, Shallow Waters in Bahrain
Authors: McGlone David
Published: March 2009

In 1996 BAPCO embarked on a project to expand the Khuff Gas Transmission and Distribution networks in Bahrain. The project was divided into four discrete segments, namely, Transmission, Distribution, Offshore and Downstream.

The paper and presentation will briefly describe the overall project and detail the challenges faced by BAPCO in the design and installation of the 3, 18" high pressure gas lines in the offshore segment.

The offshore segment links Wharf Valve Station (WVS) at Sitra to Hidd Metering Station (HMS) located some 6 km away on the east side of Bahrain on Muharraq island. This offshore section is comprised of approximately 2 km crossing the main shipping channel that provides access to the port of Mina Salman. The remaining 4 kms traversed shallow waters that, at low tide, were above the water line in some areas. One section actually crossed an offshore island that is used by migrating terns.

Challenges related to the protection of the environment during construction and subsequent operation will be detailed. Construction methods used and problems encountered, including steps taken to maintain access to Mina Salman port via the shipping channel, will be also be presented
Productivity Enhancement of Horizontal Heavy Oil Wells in the South of Oman
Authors: Zreik Bassam , Hattali Ahmed , Busaidi Khalfan , Bushara Mohamed , Tripathy Surendra
Published: March 2009

Petroleum Development Oman operates a large number of heavy oil fields in the south of Oman.

One of the fields is being developed with horizontal wells completed with sand exclusion screens and beam-pumps to produce the heavy crude oil to surface. Development drilling is in progress as per the field development plan requiring more than 10 wells to be drilled each year.

The integrated asset team carried out a post production evaluation of the 2007 newly drilled wells. The evaluation identified five underperforming wells requiring further examination to establish cause of performance impediment and to devise ways to remedy the problem.

The well performance modelling of the underperforming 2007 wells indicates very high skin values. This suggests the wells are severely damaged (e.g., reduced permeability) and/or only a fraction of the sand face is open to flow, suspect due to presence of mud filter cake. The high skin values are significantly impacting the gross fluid production consequently affecting net oil production from these wells.

A wellbore clean up and stimulation treatment was designed and well interventions scheduled to remove the suspected mud filter cake, consequently improving well productivities.

This paper reviews the production performance following wellbore clean up and stimulation of five underperforming wells. Covering well performance analysis, treatment design, execution methodology and post treatment results including the way forward to advance the current wellbore clean up process to deliver higher productivity wells in the upcoming 2009 and future drilling campaigns.
Radius of Investigation for Reserve Estimation from Pressure Transient Well Tests
Authors: Kuchuk Fikri J.
Published: March 2009

Although it is often used in pressure transient testing, radius of investigation still is an ambiguous concept, and there is no standard definition in the petroleum literature. Pressure diffusion corresponds to an instantaneous propagation of the pressure signal in the entire spatial domain when a flow-rate or pressure pulse is applied (beginning of a drawdown or injection) to the sandface of a well. However, the initial pressure propagation is not diffusive but it propagates like a wave with a finite speed. If we have a pressure gauge at a distance r in a formation, we will only start to detect a pressure change (drop or increase) after a few seconds or minutes even if we have a perfect pressure gauge with 0.0 psi resolution. After the initial propagation, pressure starts to diffuse or propagates as diffusion, and we start to observe pressure change at a given space and time above the pressure gauge resolution and natural background noise, which could be as high as 0.1 psi. One of the constant background noises is the effect of tidal forces.

In this work, we present new formulae for radius of investigation in radial-cylindrical reservoirs and a new technique for general systems. The new formulation takes into account the production rate from the system, formation thickness, and gauge resolution. It is shown that the conventional radius of investigation formula (rinv=0.029ktϕμct), see Earlougher (1977)) for radial-cylindrical systems yields very conservative estimates. Radius of investigation is fundamental for understanding the tested volume; i.e., how much reservoir volume is investigated for a given duration of a transient test? For exploration wells, the reservoir volume investigated is one of the main objectives of running drillstem (DST) or production tests. Therefore, how far pressure may diffuse (radius of investigation) during a transient test is very important for exploration pressure transient well testing.
Assessment of Uncertainty in Saturation Estimated from Archie's Equation
Authors: Zeybek Ayse Donmez , Onur Mustafa , Tureyen Omer Inanc , Ma S. Mark , Al-Shahri Ali M. , Kuchuk Fikri J.
Published: March 2009

Volumetric methods are used to estimate the hydrocarbons in place of a reservoir. They require petrophysical data including porosity φ and water saturation Sw which can not be directly measured but must be inferred from other measurements. For example, water saturation is conventionally obtained from the Archie's equation, which requires inputs of porosity, ø, cementation factor, m, tortuosity factor, a, saturation exponent, n, true reservoir resistivity, Rt, and resistivity of formation water, Rw. Uncertainties in these input values directly affect the accuracy of water saturation estimation.

In this paper, we investigate the propagation of uncertainties of these input parameters into Sw estimated by Archie's equation. Error propagation equations (based on a Taylor series expansion of Sw around the mean values of the input paramaters) are derived for uncertainty characterization. Two cases are considered for the relationship between the input parameters; correlated or completely independent. It is shown that correlation among the input parameters, which may be due to different rock facies, can increase or decrease uncertainty in Sw and hence, ignoring existing correlation among the input parameters may lead to incorrectly characterizing the uncertainty in Sw. In addition, the dimensionless sensitivities and relative uncertainties of the input parameters, derived from the error propagation equations, clearly identify which of the input parameters will dominate the total uncertainty in Sw computations. Monte Carlo methods were used to verify the developed error propagation equations. A comparative study shows that the error propagation method is a good first approximation for uncertainty analysis, especially if the resulting Sw distributions are normal. However, it is well known that Monte Carlo methods are more general as they provide rigorous sampling of the response function (Sw in our problem) by accounting for the nonlinearity existing between the response function and its input parameters, and thus should be used for accurately quantifying the uncertainty.
Successful Application of Extra-Long Expandable Cased-Hole Liner Remediates Production Well
Authors: Al-Barghawi Riyadh , Looni Qadir , Sanders Tom , Saad Marc Antoine , Stephenson David
Published: March 2009

Corrosion in the production liner of a prolific oil production well offshore Saudi Arabia has compromised the well integrity and created several significant leaks, resulting in excessive water encroachment into the produced fluids. The approximately 2,000ft section of the affected casing was across the formation containing the Umm Er-Radhuma water aquifer. Previous attempts to remedy this situation using cement squeezes were unsuccessful.

Installation of approximately 2,175ft of 5-1/2in. × 7in. expandable Cased-Hole Liner to remediate the leaking and corroded 7″ casing was successfully performed and tested. The one-trip installation proved the expandable technology in terms of its operational reliability, significant installation length, flexibility to line a combination of two different 7″ casing weights across the same setting zone, ability to apply isolation joints at selected locations and setting at a shallow depth of 718ft in this application.

The results and methodology of the operation during the installing and expanding of the cased-hole liner are further discussed to demonstrate the advances in the development of expandable technology and associated tools for such long and continuous installations. Details of the successful application are used to provide quantitave results of critical parameters that impose challenges and limitations on solid expandable technology. The installed configuration with a post expanded length of 2,081ft, which was pressure tested to 1,000psi; has proven to be the most appropriate solution for the remediation of this type of well challenge.
Numerical Modeling of Multiple Hydraulically Fractured Horizontal Wells (MHFHW)
Authors: Soleimani Arash , Lee Byung , Ghuwaidi Yahya , Dyer Steve
Published: March 2009

Horizontal wells with multiple fractures are becoming more prevalent in the Industry. They are especially beneficial in carbonate plays where acid and fracture stimulation can be used to improve productivity, the technique can be used for tight reservoirs and multiple compartments or anisotropic reservoirs with high permeability contrasts. Reliable evaluations of stimulation performance are required for field development planning. As such, pressure transients are often used, and can be successful, tight reservoirs where transient flow regimes can be used to observe and define the various impacting factors of stimulation, such as fracture length, conductivity, orientation, etc.

This project investigates the modeling and interpretation of pressure transient responses of multiple hydraulic fractured horizontal wells (MHFHW) using a numerical reservoir model. After validating the numerical model using an analytical solution applied to a simpler reservoir/well model, complex reservoirs are simulated and pressure transient response signatures obtained. Sensitivities of key reservoir/well/fracture properties are investigated and a result of each case is presented. Finally, an actual case where seven transversal fractures of a long horizontal well is modeled using a sector of the full field reservoir simulation model (geological/structural), where the results are interpreted and discussed. Fracture characteristics have been approximately estimated by comparing real well test pressure buildup analysis from field and simulation results.
Constraining Interwell Water Flood Imaging with Geology and Petrophysics: An Example from the Middle East
Authors: Al Ali Malalla , Vahrenkamp Volker , Elsembawy Saber , Bhatti Zahid , Reeder Stacy Lynn , Clerc Nicolas , Wilt Michael
Published: March 2009

Time-lapse cross-well electromagnetic (EM) surveys are used to monitor two types of fluid injection (Water Injection and Water Alternating Gas) in a giant field in the Middle East. Cross-well EM data will help optimize sweep efficiency, identify bypassed pay, and predict fluid-related issues such as water breakthrough by providing an image of the resistivity distribution between boreholes in time lapse. This paper explores the influence of a high quality background geologic model in constraining the interwell results and providing a higher resolution image of the ongoing flooding processes.

The classic EM inversion process determines a coarse (3 to 5 m resolution) resistivity distribution from a basic initial static reservoir model built from logs. This study refines the model by adding variable resolutions to encompass the small-scale heterogeneities common to carbonate reservoirs. Incorporating geological data derived from seismic attributes, core descriptions, and detailed log analyses into the static model helps optimize the EM inversion and increases the resolution of the resulting inverted model.
Increasing Production from a Shallow, Underdeveloped Reservoir in the Bahrain Field with Combination of Reservoir Analysis and Geochemistry
Authors: Abdulla Nayera Karim , Nedham Najla , Murty C. R. K. , Al Ansari Yahya
Published: March 2009

Ever since the Bahrain field was discovered in 1932, the main focus of effort was on major formations of the field, leaving shallow formations not fully exploited. Today with the increase in oil price and the depletion of major formations, there is a greater preparedness to consider increasing production from these under developed zones.

This case study was initiated with the purpose of increasing production from the Magwa zone, which is the most economically attractive of the shallow zones. The zone is the basal member of the Rumaila formation of the middle Cretaceous Wasia group. It is predominantly limestone with interbeded shale.

This case study shows an integrated methodology to enable a better understanding of the reservoir production behavior and to explain the lateral heterogeneity of the formation. This investigation was triggered by the variation in the formation water salinity from North to South. Water saturation maps, production history, geochemistry and structure set-up were used as the main input in this analysis. The interpreted relations and trends between these factors were used to explain the behavior of the reservoir. The outcome of such investigations is of critical value in determining the location of new development wells, selecting candidate wells for workover and for EOR processes.

This paper will explain how a better understanding of the reservoir through data integration has resulted in a significant increase in oil production.
Thermal EOR Pilot Plan for a Shallow Limestone Reservoir (Rubble Zone) in Bahrain Field
Authors: Murty Challa R. K. , Kumar K. , Galard Jean-Hector de , Mazeraud Virginie
Published: March 2009

Bahrain field, the first hydrocarbon discovery in the Arabian Gulf, is a multi-stacked elongated anticline structure with a stack up of 16 Oil & 4 Gas Reservoirs.

"Rubble Limestone" is the descriptive name given to a massive Limestone unit of the Mishrif formation, in middle Cretaceous in age. The zone consists of two layers, namely Upper Rubble and Lower Rubble. Both the layers are eroded in the crestal part of the structure. Large volumes of oil are trapped against the Blue shale at the up structure pinch outs of upper & lower Rubble. Fault cuts are observed in more wells indicating intense faulting and fractures.. The zone has both heavy & light oil. The amount of Heavy oil is estimated to be 90% of the initial oil in place. Currently only light oil is being produced. This paper highlights the studies to evaluate Heavy oil production potential.

Two separate studies were carried out, the first was to describe and characterize Rubble in order to map the light & heavy oil and the water bearing layers. Geo statistical methods were used to populate the 3D model of the reservoir with porosity & permeability values.

A detailed analysis of the logs indicated that light oil is associated with large separation between deep & shallow resistivity. It was observed that whenever there was heavy oil, the separation between the resistivity curves was either very less or even negative. Three rock types were identified and the habitat of light, heavy oil and water was accordingly assigned.

After obtaining an estimate of the areas of heavy and light oil, a fresh study was initiated to review and evaluate the Heavy oil prospect and to prepare a suitable thermal EOR pilot plan for the heavy oil recovery using Fraca® and PumaFlow® softwares. The study included (a) a review of the Reservoir description done earlier, (b) numerical modeling and simulation of a pilot area, (c) find out the suitable EOR process and design the pilot.

The study indicated that the reservoir has too low matrix permeability and very small fracture volumes to allow steam chamber formation. SAGD mechanism was therefore found not efficient for this reservoir. Huff and Puff has been simulated using two wells in the pilot area and found attractive. Cold production from six different Horizontal wells were simulated and tested. They indicated that cold production followed by Huff and Puff will be efficient to recover the Heavy oil.

The paper will describe the results of the study which led to drilling of the Horizontal pilot well for Cold production to be followed by Huff and Puff Thermal process.
Air Injection Potential in Kenmore Oilfield in Eromanga Basin, Australia: A Screening Study through Thermogravimetric and Calorimetric Analyses
Authors: Sarma Hemanta , Das Shyamol
Published: March 2009

Although air injection process has been a proven low-cost EOR technique for tight high-temperature light-oil reservoirs elsewhere, there has not been any Australian field application even though several reservoirs appear to meet the screening criteria for the process. Moreover, air injection could be a more attractive alternative for reservoirs that are amenable to hydrocarbon gas processes, thus freeing "cleaner and greener" gases for use for energy resource. Moreover, unlike most EOR processes, the air injection process does not require water, a scarce natural resource in Australia.

In this screening stud, y Kenmore oilfield in Eromanga Basin operated by Beach Petroleum has been chosen as the candidate oil. Kenmore reservoir is a 1395-m deep tight (4.4mD) light-oil (48.7°API) reservoir at 92°C. As the process feasibility depends primarily on the oxidation characteristics of the oil and its ability to sustain the ignition front during the process, the first step undertaken is the thermogravimetric and calorimetric characterization of Kenmore oil to (i) identify the temperature range over which the oil reacts with oxygen, (ii) examine the oxidation behavior within the temperature range identified, and (iii) evaluate the mass loss characteristics during the oxidation.

A series of thermogravimetric analysis (TGA) and pressurized differential scanning calorimetric (DSC) tests were conducted on Kenmore oil. Tests showed two distinct exothermic reactivity regions of temperatures within 200-340°C and 360-450°C, with an 85-95% mass loss when the temperature reached 450°C. Endothermic reactions are attributed to evaporation, distillation, and thermolysis; whereas exothermic reactions are due to low temperature oxidation, pyrolysis, and high temperature oxidation. It was observed that at an elevated pressure resulted in accelerated the bond scission reactions, a positive sign as far as the application of the air injection process is concerned; for, it suggests that Kenmore oil has the oxidation potential under high pressure air injection.
A Structured Approach to Benchmarking Bit Runs and Identifying Good Performance for Optimization of Future Applications
Authors: Miller C. , Duerholt R. , Richards A. , Briggs N.
Published: March 2009

Performance analysis of large numbers of bit runs is often anecdotal and uses historical cost data. To this end, there are numerous problems with this approach. There is no uniform approach to identifying good performance. At best, the analysis provides an imprecise picture of overall performance. Large datasets need to be condensed into runs of interest. Difficulties arise when comparing multiple runs through long intervals with variable thicknesses of hard stringers. Since BHA, rig, and other costs change over time, it is problematic using historical cost per foot (CPF) data for the current target well. Finally, how does one determine if long slow runs or short fast ones are better since both could have the same CPF?

In this paper, the authors discuss a structured benchmarking method that can be applied regardless of the application or area studied. The basic process is simple and can be tailored to the requirements of different applications. The goal is to deliver a statistical benchmarking process that helps filter large sets of data and facilitates a consistent approach to bit performance analysis that is independent of historical cost data. A process flow chart is developed to guide engineers step-by-step through the benchmarking method. Good offsets are identified and included in the benchmarking population. Eligible bit runs are then ranked by a new key performance indicator (KPI): ROP*Distance Drilled. No historical cost data is included in the analysis. A detailed engineering study is then carried out on the identified best runs to develop recommendations for future applications. As the last step of the process, a financial analysis is carried out using cost data for the current well.

The paper will describe the use of this process to analyze bit performance in the operator's gas drilling operation and show how it allowed the identification of ‘true’ unbiased top performance. The benchmarking process standardizes performance analysis and ensures sound engineering principles are applied resulting in a better understanding of past performance and better recommendations for future applications.
Taking Advantage of Real Time Data in Upstream Operations
Authors: Wiemers Suzan
Published: March 2009

ExxonMobil Upstream has a standard global operations surveillance tool for new production sites which has been in use since 2003. The solution is a data historian which together with customized graphical user interfaces enables delivery of real time data to engineering, operations, and management desktops in startup production operations. The uptake success and popularity of this tool has led to expanded use in existing fields. A globalization project is now underway to ensure delivery to all key production assets by 2011 while continuing to deploy to new operations. Strategies and production examples presented in this paper exemplify "Digital Oilfield" principles: people, technology, processes. Business challenges solved with standard global technology solutions demonstrate successful operations at an enterprise level.
Quest for a Pragmatic Drilling Fluid Performance Index—Key to Improving Fluid Performance and Optimising Quality Well Delivery Economics
Authors: Osode Peter , Al Farsi Mohamed , Stevenson Eddie
Published: March 2009

Over the years there have been numerous attempts at establishing a key performance-measuring index (KPI) that would allow comparisons to be drawn with drilling activities in different locations. In the case of drilling fluids no model has gained any universal acceptance and measuring performance in this activity has typically been left to the ‘easy to acquire’ cost/m or cost/m3 per interval drilled on a campaign well basis within a specific field.

Drilling fluids cost across the oil industry range between 5–25% of the well construction costs. If we continue with the traditional cost focused indices then at the low end of this range there is no visible incentive to reduce costs and hence no drive to measure nor improve performance in many of our locations.

The real drivers to improve performance lie with the impact on the overall well performance and field development economics in terms of Non Productive Time (NPT) and deferred or impaired production and these can be significant. A pragmatic approach is being developed within Petroleum Development Oman (PDO) that embraces the importance of NPT data as a measure of drilling performance and addresses the issues of production performance of the well to identify well improvement opportunities.

This paper reviews the existing mud performance parameters and their drawbacks, presents a practical prediction technique for drilling mud cost based on existing offset field/well data which is less complex than the typical functional drilling cost models (Kaiser 2007)1 and describes how to integrate mud-related cost factors into a simple Mud Quality Index (MQI) equation. The underlying assumptions and limitations of the new KPI will also be discussed to determine any further improvements deemed necessary. Using real data from some PDO fields, MQI data was generated for a group of wells and compared to the old mud cost matrix data to show the disparity in the wells performance ranking based on the different KPIs. The KPI tool is expected to facilitate drilling fluids planning, design and management decision-making on the capital-intensive exploration, deep appraisal and development drilling projects when fully deployed.
An Integrated Approach Towards Building an Enterprise GIS System for Petroleum Industry
Authors: Puripanda Naresh Kumar , Shamsan Fahad
Published: March 2009

With rapid advancement in technology and familiarization with spatial imageries, Petroleum Industry users see the benefits of organizing and managing information geographically using GIS, especially for companies with huge data like Bapco. An Enterprise GIS System was initiated and being implemented within Bapco.

The enterprise GIS system will help to manage data related to all aspects of Bapco's business units in an effective manner. A number of feasibility studies & workshops like Business Change, System Benefits, Success Measures, Application / Data need assessment, Stake-Holder Meetings have been held. The GIS need assessment includes a review of user work requirements and identifies where GIS application can improve user productivity and quality. The information system includes data from Oil and Gas assets, production, transmission, marketing, exploration, refining, environmental etc. The Enterprise GIS System is expected to provide a cost-effective method to access, monitor, analyze and manage data that is spread in different areas within the company and bring them under one platform. This migration consolidated fragmented data into a centralized repository; integrating with external applications and work flow processes like Petrovision, Wellview, OGN, OFM, IP, Petrel, Geoframe, IESX, Gocad, Pipesim, etc; and serving data to the enterprise GIS System.

This paper discusses the approach adopted by Bapco towards building an Enterprise GIS System.
Best Cleanup Practices for an Offshore Sandstone Reservoir with ICD Completions in Horizontal Wells
Authors: Shahri Ali M. , Kilany Khalid , Hembling Drew , Lauritzen J. Eric , Gottumukkala Varma , Ogunyemi Olusegun , Moreno Oscar Becerra
Published: March 2009

Achieving effective cleanup while flowing back the well after drilling is key for maximizing productivity and minimizing near wellbore damage. This paper discusses the best practices for cleanup in a sandstone reservoir drilled with oil-based mud (OBM), and installed with inflow control device (ICD) completions. The findings are based on the evaluation of different cleanup methods: coiled-tubing deployed nitrogen kickoff, chemical treatments, artificial lift-electric submersible pump vs. natural flow, time spent on cleanup, and flow rate.

Applications include sand control completions run in open hole with ICDs over long horizontal sections. Results show that in relatively high darcy sands, using proper chemical treatments and spending more time for flow back with higher rates will maximize productivity and minimize near wellbore damage. Choosing the correct and effective cleanup method will minimize near wellbore skin, maximize productivity, effectively drain the reservoir and save intervention costs for cleanup.
Production Enhancement for Khafji Field Using Advanced Optimization Techniques
Authors: Al-Khaldi Mohammad A. , Ghoniem El-Sayed Ouda , Jama Ali Ahmed
Published: March 2009

The gas lift, by limited capacity of 25 MMSCF/D, was introduced for Khafji field in 1988 which could successfully sustain target rate until mid of 2004. Artificial Lift is part of the long term production sustainability solutions for Khafji Field necessitated by the increase of field water cut and depletion of reservoirs. In order to make up for production decline in Khafji Field and to sustain the field target rate and defer large investments associated with exploration and drilling new wells as well as commissioning new facility expansions, Production Optimization and de-bottlenecking of the existing production system was found to be the best cost effective solution. For that purpose, general optimization and gas lift allocation models have been built and applied for Khafji field as presented by Ghoniem et al1, 2.

This paper is an extension to the previous papers for Khafji Field cited above. The optimization approach presented in this paper is based on a field-wide production planning solution, which is achieved by combining steady-state multiphase network simulation with a nonlinear, multivariate optimization technique called Genetic Algorithm (GA) through a newly developed and commercially available optimization application called Avocet Gas Lift OptimizerTM.

The present work therefore represents the introduction of a new optimization platform for Khafji crude production and its results with a particular focus to:Building a comprehensive network model for Khafji Field (including wells and production facilities).Demonstrating production gain by the use of advanced optimization techniques (e.g.GA) to sustain field quota.Optimally distributing limited gas lift availability to Khafji Field to enhance production, while taking into multiple well and field constraints.

Introduction

Khafji field lies in the Arabian Gulf, 40 km east of Al-Khafji city, Saudi Arabia (Fig. 1).The field is composed of several reservoirs for sweet crude. The most prolific ones are 1st and 2nd Bahrain sand. Where, a strong and an active aquifer provides pressure support and water drive to 2nd Bahrain and to a lesser extent to 1st Bahrain. In addition, four other oil reservoirs are currently active namely Ahmadi limestone, B-limestone, Wara sand and Zubair sand which are commonly referred to as minor reservoirs.

In Khafji field, there are approximately a hundred wells which are already completed with gas lift injection system. Even though, many remaining gas lift wells are still producing naturally with lower rate, some others are currently being shut in. Thus, the most effective wells for gas lift operation were defined by performing lot of screening using gas lift allocation models.
Method to Generate Fullbore Images Using Borehole Images and Multi-Point Statistics
Authors: Hurley Neil F. , Zhang Tuanfeng
Published: March 2009

Borehole image logs, produced by tools lowered into a well, provide oriented electrical and acoustic maps of the rocks and fluids encountered in the borehole. Electrical borehole images in water-based (conducting) and oil-based (non-conducting) muds are generated from electrodes arranged in fixed patterns on pads that are pressed against the borehole wall. Depending on the borehole diameter, gaps nearly always occur between pads. Because of these gaps, it is common to have non-imaged parts of the borehole wall.

Fullbore images are complete, 360-degree views of the borehole wall. They are generated by "filling in the gaps" between the pads of borehole-image logs. This method uses the FILTERSIM algorithm of multi-point statistics to generate models, or realizations. Measured (incomplete) borehole images themselves are used as "training images." Recorded data are perfectly honored, i.e., the models are conditioned to the real data. Gaps are filled with patterns similar to those seen elsewhere in the log. Patterns in the gaps match the edges of the pads. The frequency distribution of continuously variable pixel colors in the gaps matches the distribution of pixel colors in the measured images.

Fullbore images facilitate visualization and interpretation of borehole-image logs. They can be used to draw closed contours around electrically resistive or non-resistive patches in the borehole wall. Fullbore images can be used to repair logs with bad electrodes, low pad pressure, or poor acoustic reflections. Therefore, they can be used to enhance any commercially available electrical or acoustic borehole images.
Expandable Sleeve Isolate Shallow Aquifers
Authors: van de Velden Mark , Al-Houqani Said , Al-Busaidy Hilal , Saltel Jean-Louis
Published: March 2009

A major Middle East Operator has adopted a new type of solid expandable tubular technology to isolate shallow aquifers as well as fractured formations. The technology is based on a steel wired balloon expanding a stainless steal into the well bore. The simplicity of the technology combined with a significantly increased expansion ratio has opened a whole range of new applications to materialize low cost wells. This paper will outline the two trial wells in which the technology was applied, review the benefits of expandable tubulars for these applications as well as looking in candidate selection. Particular emphasis is given on the Operator's experience with the technology.

Isolation of shallow aquifers and fractured formations while drilling has been a major challenge for many years in Oman. The requirement for zonal isolation of the shallow aquifers is often compromised by the total losses encountered. Often a cocktail of chemicals followed by multiple cement jobs are used to achieve the objective. The latter can be costly not to mention the extra time incurred and HSE exposure. Also failure to isolate aquifers also increases the risk of cross flow between fractured formations what has been a significant contributor towards free water corrosion of the surface casing strings as well as subsequent issues referring to un-cemented casing strings in thermal wells.

Inflating a sleeve into the formation has proved successful in terms of installation reliability, isolation of fractures and isolation of shallow aquifers. Well configuration based on expandable tubular solutions have improved well delivery times what is making this expandable technology a strong case for wells to be drilled in the coming years.
Identification and Characterization of Producing Fractures in Naturally Fractured Reservoirs Using PIWD
Authors: Berkat Ali , Kartobi Khelil , Cherif Mazouz M , Qutob Hani , Barakat Naiem
Published: March 2009

Early recognition of a fractured reservoir and an estimation of its rock characteristics, such as porosity and permeability, will influence the location and number of subsequent development wells and, therefore, is of major economic significance on the future development of the field.

Underbalanced drilling provides an unprecedented opportunity to examine a reservoir as it is being drilled. With proper data acquisition and engineering interpretation, underbalanced drilling allows us to measure and calculate the Productivity Index while Drilling – PIWD. This data helps us locate and identify geologic anomalies such as fractures, tight zones, pinch outs, discontinuities, and water zones. A better understanding of the fracture networks and their impact on the production is critical to optimize infill drilling and produce the remaining reserves in any reservoir. Also, PIWD graph is a good indicator of reservoir productivity characterization. The real time data obtained using this graph can clearly show what kind of reservoir is being drilled and what kind of production can be expected.

This paper reviews and analyzes oil production while Underbalanced Drilling of two wells in Hassi Messaoud field, Algeria. The interpretation of PIWD graphs demonstrates the existence of producing fractures. The results were confirmed during the Build-up test interpretation. Also, the image logs were correlated with production data to make sure they are in agreement. Every point on the image logs where signs of fractures were observed were studied and compared to the PIWD profile to establish a correlation type. This review is an attempt to examine the ability to predict the presence of fractures in future UBD wells in Hassi Messaoud field based on the production while drilling profile where image logs can not be run.
Meeting the Challenges of Natural Gas Market in Bahrain
Authors: Al-Mahroos Faisal , Al-Anaisi Abdulla
Published: March 2009

Natural gas is the main source of energy for the Kingdom of Bahrain and contributes more than 85 % of the total energy consumption in the country. The main source of gas is the Khuff reservoir which was discovered in 1948. These abundant gas reserves were stranded for 20 years as no commercial or monetization projects were forthcoming.

However the rapid increase in industrialization program since 1969, compelled a steep demand for electricity and hence the increase in gas production. The steady demand growth driven primarily by power sector will continue to increase by about 4% annually while the industrial sector will be supply constrained.

Maturation of both the gas supply and the emerging gas markets raise issues of concern on the supply side as well as the demand side.

On the supply side, drop of reservoir pressure results in lower well deliverability and loss of natural cooling effect while water encroachment will result in drop in wellhead pressure, gas souring and water production. These require huge investment to ensure adequate gas supply.

On the demand side, the uneven growth of power sector (which consumes most of the gas) and the fluctuations in peak gas consumption leads to large uncertainties in the development of the field. Technologies and efficiencies as well as the economic cycles also represent additional concerns on the demand side, in addition to the large lead times that are required to build facilities and acquire equipment.

Even to maintain the current levels of energy demand alternate sources of gas / energy supply have to be cultivated. As this will come at a certain cost, it will have a significant impact on the economy of the Kingdom.

This paper discusses the effects of all the above issues on this mature asset and draws conclusion from experience of Bahrain on sustaining the long term economic growth by effectively managing its domestic natural gas supply and demand balance.
Utilization of In-Situ Gas Lift System to Increase Production in Saudi Arabia Offshore Oil Producers
Authors: Warren Phillip , Logan Sami , Zubail Makki , Balto Abdulelah , Perez Simeon , Aramco Saudi , Villarreal Adrian , Becerra Oscar
Published: March 2009

This paper discusses the first Smart in-situ gas lift systems that were installed in three Saudi Arabia offshore wells. These Smart in-situ gas lift systems have proven to work in an offshore development environment for production enhancement. Implementation of this technology will extend the well life by allowing high water cut wells to produce, rather than become inactive, due to high hydrostatic back pressure in the wellbore. The selection of this system, which uses reservoir gas cap energy as compared to other artificial lift methods, resulted from economic considerations and operation simplicity in a non-electrified offshore field.

The primary focus of this paper will be to discuss the first in-situ gas lift equipment, completion installation procedures, field test results, operation principles utilizing the gas cap energy, production strategy and well performance using an online monitoring system, and reservoir management considerations for future installations within the field.

Initially, five conventional in-situ gas lift systems were installed in the field with problematic downhole sliding sleeve assemblies that required wireline intervention. As a result, Smart in-situ gas lift systems were recommended to allow auto opening of the downhole gas lift orifice valves from surface. These Smart systems have proven their durability over conventional systems, and will extend well life at a relatively higher water cut and maximize reservoir sweep efficiency.
Hanifa Exploration Potential on the Flank of the Bahrain Field
Authors: Qassim Naji , Pathak Ravi Kant , Al-Alawi Habib
Published: March 2009

The Jurassic Hanifa formation is known to be a very good regional source all over the Arabian Gulf and it is reported to be producing in some of the fields in the area. This study focuses on the Hanfia exploration potential especially around the flank of the Bahrain field. It has been observed that some of the wells in N.Eastern flank of the Bahrain field are showing some indication of oil in the Hanifa reservoir. Theoretically, stratigraphic porosity and permeability controlled traps are expected between NE Bahrain Wells and the Bahrain field.

Based on seismic attributes analysis and inversion as well as integration of well data the full potential of this formation is being assessed.

Introduction

The Jurassic petroleum systems of the Arabian Peninsula form one of the most prolific petroleum producing system in the world. Source rocks of this system extend throughout the eastern Arabian Peninsula and Arabian-Persian Gulf. Primary elements of this Jurassic petroleum system - source, reservoir and seal rocks—are of great areal extent. The regional extension of this petroleum system and formation of subtle structural closures and / or stratigraphic traps prior to, or coincident with hydrocarbon generation and migration are significant for prospect generation. Structures that trap hydrocarbons in this system in Arabian Peninsula are mostly 1) large, gentle anticlines formed from reactivated basement fault blocks, 2) salt domes and 3) structural traps resulting from combination of these two processes. Hanifa oil accumulation is also reported within stratigraphic traps due to facies change.

Hydrocarbon presence has been reported during drilling OF well #F #H n the Middle Jurassic section within Hanifa. Hydrocarbon shows were also reported within Hanifa at Well #C All the above wells are located at north-east flank of Awali. It is interesting to note that Hanifa section encountered at up dip Well #A was found to be water bearing.

This integrated study was initiated to outline the Hanifa prospect at Awali flank in general and north-east flank (Fig 1) in particular. The preliminary finding of the study as well as further G & G work envistaged to convert it into drillable prospects is documented in this study.
Improving Fracture Network Model of AB Reservoir through Integration of Seismic Multi-Attributes- A Case Study from Awali Field Bahrain
Authors: Qasim Naji A. , Hermann Behira , Pathak Ravi Kant
Published: March 2009

The upper Cretaceous Ab reservoir within Ahmadi formation at Awali field is considered to be deposited over a broad, gently sloping carbonate ramp. The main reservoir lithofacies are bioclastic packstone, bioclastic packstone/wackestone, bioclastic wackestone and argillaceous wackestone/lime mudstone. The reservoir is characterized with moderate porosity (15%) and low permeability (.1 MD). The average production of wells is about 15 BOPD. However, there is wide degree of production variability due to matrix porosity variation and fracture distribution. The well productivity is relatively high in the areas with high fracture density. Accurate Fracture network model would contribute significantly for efficient recovery from the reservoir. Seismic 2D curvature attribute has been a valuable tool in mapping of fault networks. In the study, seismic curvature attributes along with horizon based and morphological attributes such as dip-azimuth, coherency, edge, 3D curvature have been successfully used together to improve the Ab Fracture network model.

The paper describes the workflow used in extracting Principal curvature attributes from 3D seismic data. The 2D curvature attribute helped in detection of many new fractures having lineaments consistent with the identified faults and fractures. This was followed by a Fracture Seismic Facies Analysis: it consists of fracture-related seismic multi-attribute analysis and statistical classification in order to select optimum set of attributes providing best geologically consistent representation of fractures.

From this Fracture Seismic Facies Analysis, it was inferred that fractures were best represented by facies corresponding to high to mid curvature, high edge and low coherency. The fracture facies so derived was calibrated with FMI & other well information and was used for preparing the improved Fracture network model.