bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated Reservoir Characterization Using Facies, Rock Texture and Flow Units Applying Rock Typing Approach, Upper Cretaceous Reservoir, Abu Dhabi Onshore Oil Field, UAE
Authors: Hozayen M. A. , Al Saadi H.
Published: February 2011

Detailed geological characterization is vital control in describing complex oil reservoirs. This work is a detailed reservoir description of a highly heterogeneous Upper Cretaceous carbonate reservoir consisting of limestone; of variable textures, and dolomite in one of Abu Dhabi onshore oil fields. The reservoir thickness ranges from 300ft to 600ft and characterized by high degree of heterogeneity with widely variable porosity and permeability. The study includes geological evaluation; detailed lithofacies description using some 7000 ft of cores and 6500 thin section descriptions on foot by foot basis, paleoenvironment interpretation, detailed High Frequency Sequence Stratigraphic interpretation using cores integrated with seismic data, and diagenesis. This is followed by a Reservoir Rock Types (RRT) study using rock textures as a driving tool and Flow Unit approach.

This comprehensive integrated multidisciplinary reservoir characterization study was conducted considering all available data including logs, cores, Mercury Injection Capillary Pressure (MICP), Flow Zone Index (FZI), Reservoir Quality Index (RQI) and Pore Throat Size Distribution (PTD) that were used to define the various Reservoir Rock Types for the reservoir characterization and description purposes. Five attempts were experienced incorporating various combinations of logs, cores parameters and MICP data to reach to a reasonable and robust rock type scheme. Eventually 9 RRT are defined in the cored wells and they will be predicted in non-cored wells as well as in between wells in 3D using specific 3D software. The outcome will be a 3D Reservoir Static Model, derived by rock texture and flow units which will be used for Reservoir Engineering Dynamic Flow Reservoir Simulation Models.
Robust Implementation of Corrosion Inhibition Squeeze CIS Program Extends the Well Completion Lifetime Case Study
Authors: Samad Saleh Abdul , Sawadi Obadah Al , Odeh Nadir , Afzal Mohamed
Published: February 2011

Oil producers completed with carbon steel were threatened with sweet corrosion due to early water breakthrough and the presence of carbon dioxide in the associated produced gas. In severe cases corrosion led to problems which interrupted production and put the wells in an unsafe service condition. Remediation or replacement of damaged tubing was not cost effective or not feasible. A robust corrosion inhibition program through periodic squeeze treatment was implemented. Optimized and improved through the years it provided effective protection of the downhole completion and extended well operating lifetime.
Risk Register and Risk Ranking of Non Integral Wells
Authors: Al Braiki Saleh Abdul , Al Sawadi Obadah S. , Afzal Muhammad , Khan Naeem
Published: February 2011

Non-Integral Wells are common in every aged field and managing their integrity is becoming a challenging issue, particularly in large fields and for complex dual completions such as the case in ZADCO operated fields. As part of the Well Integrity Management System (WIMS), integrity concerns are identified, investigated and subsequently mitigation measures are recommended to restore the well integrity, all in a systematic approach. Well barrier integrity is given the highest priority; therefore a comprehensive Risk Register and Risk Ranking process is implemented by ZADCO Well Integrity Team.

The Risk Register process utilizes every related data and integrity investigation results to evaluate the integrity of the well primary & secondary barriers for every flow path. An individual integrity assessment is performed on the different containment sections in a well such as wellhead, inner and outer annuli and zonal isolation. Based on the severity, consequences and likelihood of a barrier failure the individual containment is given a risk rank according to ADNOC/ZADCO risk matrix. The overall risk ranking of a well reflects the highest risk rank of any of its containments. To complete the risk register, existing safeguards are addressed and appropriate short and long term mitigation actions are recommended to keep the risk at ALARP.
3D OBC Seismic Survey Geometry Optimization Offshore Abu Dhabi, U.A.E.
Authors: Ishiyama Tomohide , Mercado Gary , Belaid Kamel
Published: February 2011

The flexibility of 3D ocean bottom cable (OBC) seismic survey design enables a variety of survey geometries. Among the infinite variations, we naturally seek higher survey efficiency within operational constraints. Therefore, it is important to consider operational constraints placed upon the geophysical requirements by equipment capability and productivity, and to discuss geometry options in order to optimize the geometry of a survey in a field, satisfying not only the geophysical requirements but also the operational constraints. We analyzed several geometry options, such as zippers between panels, source line interleave, flip-flop shooting, outboard shooting and distance separated simultaneous shooting (DS3), to solve limitations in equipment capability, to pursue higher productivity, thus to optimize the survey geometry. We show that this exercise should bring insights into higher survey efficiency within the operational constraints in order to optimize the geometry of a survey in a field.
Do You Really Need That Rotary Steerable? An Evaluation of Applications and Comparisons with High Performance Mud Motors
Authors: Malcore Eric , Murray Bruce
Published: February 2011

The benefits of running rotary steerable tools have been widely advertised and accepted. Borehole quality, higher ROP’s and less torque and drag are all potential benefits to running rotary steerable tools. Is the rotary steerable tool a catch all for all applications? The purpose of this paper is to review when a rotary steerable tool can be most effective and when it might be better to just run high performance mud motors.

The development of rotary steerable tools has changed the directional drilling and even performance drilling landscape forever. Rotary steerable tools can allow longer laterals than ever before. They allow casing to be run where it was difficult to run before and allow weight transfer when it was impossible to get it.

But in some applications, it might be more cost effective to use high performance mud motors. A properly engineered BHA with the right drilling tools and motor / bit combination can out drill a rotary steerable system in many applications.

This paper will review the proper application of rotary steerable tools and also present case studies where properly engineered mud motor BHA’s have out performed rotary steerable BHA’s.
Seismic Sequence Stratigraphy in Mapping Complex Reservoir Reef Build-up Geometries (Offshore Abu Dhabi field)
Authors: Bellah Samir , Shateri Abdulla Al , Kumpas Michael G.
Published: February 2011

Reservoir zonation in a prominent offshore Abu Dhabi oil-field has been investigated by means of seismic sequence stratigraphy. The field is producing from a Rudist reef complex where only discrete zones yield high production rates. An advanced seismic sequence stratigraphy study was conducted with the objective to refine the interpretation and understanding of the extent and thickness variation of the producing zones to optimize further development of the field.

This paper presents the methodology and results of a seismic sequence stratigraphic study using innovative technique for the extraction of chronostratigraphic relationships embedded in the seismic data. The underlying concept of the method used is that all stratigraphic events are detected and placed in stratigraphic order. These chronostratigraphic events or surfaces are generated at sub-seismic resolution and tracked throughout the seismic volume within the limits of user-determined bounding surfaces – picked horizons. The integrity of the results is supported by ties to wells and good consistence with a conceptual, traditionally accepted reef complex model.
Twin-Tailed Surfactants for Creating CO2-in-Water Macroemulsions for Sweep Enhancement in CO2-EOR
Authors: Sanders Aaron W. , Nguyen Quoc P. , Nguyen Nhut M. , Adkins Stephanie S. , Johnston Keith P.
Published: February 2011

Several classes of surfactant have previously been reported for creating emulsions in the oilfield, but primarily these surfactants were originally designed for the interface of oil and water. We report here on the design and synthesis of a new class of twin tailed surfactants based on glycerin and designed for the supercritical (sc)CO2-water interface.

CO2-Enhanced Oil Recovery (CO2-EOR) is very efficient in terms of oil displacement, but due to the low viscosity of scCO2 suffers from poor sweep efficiency. One method of increasing sweep efficiency in CO2-EOR has been through the use of surfactants to create "foams" or more correctly CO2-in-water (C/W) macroemulsions. Traditionally surfactants have been used "off the shelf" which were designed to lower the interfacial tension (IFT) of oil and water.

The design and synthesis of twin tailed surfactants for use at the CO2/water interface is discussed. The hydrohobes for these surfactants are synthesized from epichlorohydrin and an excess alcohol. Subsequent ethoxylation of the resulting symmetrical dialkyl glycerin yields the water soluble dual tailed surfactants. The general characteristics of the surfactants in water are described. Twin tailed surfactants have been shown to be more effective at lowering the surface tension (25.6 dynes/cm at CMC) compared with secondary alcohol based surfactants such as Tergitol™ 15-S-12 (33 dynes/cm at CMC), however, due to the unfavorable packing the efficiencies of these surfactants is lower than their linear counterparts. At the CO2/water interface the lower interfacial tension is not as strong and therefore the CO2-philicity of the hydrophobe determines the surfactants ability to migrate to the interface. The higher CO2-philicity of the dialkyl glycerines leads to strong adsorption at the interface and a low interfacial tension.

In this report we compare the twin-tailed dioctylglycerine surfactants with a linear secondary alcohol surfactant in a side by side comparison in a core flood. The results show that even above the cloud point of the surfactants, the twin tailed surfactants create a significant mobility reduction, likely due to favorable partitioning into the CO2 phase. The data covers surfactant structures designed specifically for the CO2-water interface and can be used by producers and service companies in designing new CO2-floods, especially in areas that might not have been considered due to problems with reservoir inhomogeneity.
Relative Culture Strength – A Key to Sustainable World-Class Safety Performance
Authors: Van Westhuyzen Johan
Published: February 2011

While workers in the oil and gas industry tend to work safely, in general, most enforcement mechanisms are compliance-based, often focusing on safe conditions rather than safe behaviours. As a result, the frequency of injuries and accidents remains static, with several incidences per year. By embracing a behaviour-based system, in which employees are trained to think consequentially and work safely, companies can cultivate a self-reinforcing safety culture that has the potential to make the goal of zero injuries and accidents a reality. Intrinsic to success is the ability to quantify and measure progress towards a sustainable safety culture, one that allows companies to chart progress and adapt strategies to ensure a positive outcome.

To this point, DuPont initiated a survey in 1999 to determine why one plant site might have outstanding safety performance while another in the same business has poor performance. Though much qualitative analysis had been conducted on this issue, no quantitative analysis had been performed to validate the relationship between safety culture and safety performance. As such, the goal of this survey was to evaluate employees’ perceptions of their safety programme and identify behaviours, attitudes and other factors that have the potential to undermine a safety programme.

Results from the survey were analyzed, specifically focusing on how the safety culture varied between organizations with poorer safety performance and those with excellent performance. The Total Recordable Injury Rate based on the US Occupational Safety and Health Administration (OSHA) model was used as the measure of safety performance. Using collected data, the value of Relative Culture Strength was determined to normalize question responses in reference to its benchmark poor and benchmark best values.

Ultimately, the data showed a pronounced relationship between safety culture and safety performance, with leadership as a key variable. The number of injuries is inversely proportional to Relative Culture Strength. The development of this metric thus allows for the quantification of qualitative data pertaining to safety culture, making it possible to benchmark safety culture within a company, an industry and across industries. As such, the metric has proven an effective measure for assessing and catalyzing safety culture improvement. This paper will review the data provided by the Safety Perception Survey, sharing insights, trends and analysis pertaining to safety culture. Moreover, it will serve to assist managers in better understanding the utility of a safety culture, as well as its role in improving safety performance.
Redevelopment of the Cardium Formation Using Fractured Horizontal Wells: Reservoir Engineering Perspectives and Early Case Histories
Authors: Omatsone E. N. , Bagheri M. A. , Galas C. M. , Curtis B. , Frankiw K.
Published: February 2011

According to the Alberta Energy Resources Conservation Board, the Cardium Formation holds about 25% of Alberta's total discovered conventional oil resource, amounting to over 10 billion barrels of oil-in-place. In spite of its enviable size, oil quality (36 to 40 degrees API) and significant dissolved gas content, the cumulative production from this clastic play, as of December 2009, was approximately 1.75 billion barrels (since the onset of oil production in 1957). This represents an achieved Recovery Factor of only 17%, from a combination of primary, secondary and tertiary recovery schemes with predominantly vertical drilling in various parts of the formation. Since late 2008, however, operators have shown that redeveloping the Cardium Formation with multi-stage hydraulically fractured horizontal wells has the potential to significantly increase production by increasing reservoir contact in the undeveloped and under-developed areas.

This paper presents a brief review of the historical performance of vertical wells in the low reservoir quality areas of the Cardium and then describes the impact of placing multi-stage fractured horizontal producers in these areas. The paper deals with the redevelopment of the Cardium Formation from a primary recovery perspective only – with a focus on the fringe areas around the super-giant Pembina field as well as the development of the largely untapped resource in the "A" lobe of the Cardium in the Garrington/Caroline areas. The development of these portions of the Cardium constitutes an extension to previous estimates of Original Oil-In-Place and significant additional recovery potential. The performance of the over 120 multi-stage fractured horizontals that have been placed on production (as of June 2010) is discussed from geologic, reservoir engineering, development modeling and economic analyses perspectives. The authors include some proposals for "typical" Cardium horizontal well performance profiles for reserves assignment purposes and, in closing, they present some data-gathering and forward-modeling recommendations for Cardium operators/stake-holders that would enable them to maximize the near- and long-term values of their assets.
Modeling Transient Vibrations While Drilling Using a Finite Rigid Body Approach
Authors: Pabon J.. , Wicks N.. , Chang Y.. , Dow B.. , Harmer R..
Published: February 2011

Vibrations are a common contributor to premature drillstring failure. The need for a better understanding of the phenomenon has driven the implementation of real-time downhole drilling mechanics measurements. As the costs associated with poor drilling performance and equipment failures increase, so does the impact of improving the modeling of these vibrations.

The onset of downhole vibrations is complex and sensitive to a wide range of factors, some of which are difficult to quantify within a typical drilling environment. Examples of these factors are the friction factor at contact points, drillstring component imbalance and rock properties and their variability. Field experience has shown that the identification of resonant conditions using frequency domain modal analysis is of value; however, additional insight can be gained through the use of a transient vibration analysis.

This paper describes a numerical modeling tool developed to enhance understanding of the transient dynamics undergone by a drillstring during the drilling operation. A Finite Rigid Body (FRB) approach has been chosen for modeling simplicity, computational cost, and physical relevance of the computed results. This approach can be used to incorporate important transient features characteristic of a drilling operation, such as the bit-rock interaction and the interaction of the drillstring with the borehole wall, as well as the relevant dynamics introduced by drilling tool components such as mud motors and bit steering devices. A number of examples and case studies illustrate the capabilities of the modeling tool.
New Approach and Technology for CO2 Flow Monitoring and Remediation
Authors: Sweatman Ronald , Marsic Scott , McColpin Glenn
Published: February 2011

A novel, cost-saving approach combining rapidly-acquired CO2 flow measurements and early-alteration improves CO2 placement, leak detection, and remediation in CO2 enhanced oil recovery (EOR) and carbon capture and storage (CCS) projects. The approach is based on field-proven technologies for monitoring CO2 flows and for controlling flows within reservoirs or remediating flows outside of reservoirs. The new low-cost monitoring technology employs reservoir flow induced micro-deformation measurements by three basic technologies—satellite-based interferometric synthetic aperture radar (InSAR), surface and downhole tiltmeters, and differential global positioning systems (GPS). These methods acquire microdeformation data in near-real-time (NRT). This data supports NRT geomechanical inversion analysis that provides 3-D reservoir flow images. Real-time temperature and pressure data from wells instrumented with sensors connected to fiberoptic cables may also be used to better characterize some CO2 flows. The new lost-cost flow control and remediation technology is derived from improvements in flowpath sealants and placement methods that can alter flows both inside and outside of reservoirs.

This monitoring technology has evolved from similar methods proven in other types of secondary and tertiary recovery projects, and more recently in CCS projects, to identify reservoir flows and pinpoint abnormal ones. An example of normal CO2 flow results is presented to show how operators can calibrate flow-prediction software models and make fast decisions to apply flow enhancing methods. These methods improve CO2 sweep efficiency, increase oil production, and better utilize the reservoirs’ CO2 storage capacity. Another example shows the early identification of an abnormal flowpath location that enables timely selection of sealing methods and materials that eliminate unwanted flows from reservoirs with negligible CO2 losses.

The CO2 flow control and remediation technology’s history of field-proven success is described along with recent developments that have improved both material and placement performance. Generic case histories of conventional vs. the proposed new approach are compared to show how the combination of rapidly-deployed, CO2 flow-alteration and monitoring technologies creates synergies that can improve the performance of CO2 EOR and CCS projects while reducing operating costs.
Unique Selection Tool Enables Scientific Approach to Matched Reamer Assemblies
Authors: Barton Steve , Weeden Ryan
Published: February 2011

There is a critical need to understand the interaction between a drill bit and underreaming tool in hole opening assemblies. Problems that can result from improper matching include vibration, inability to open hole, mechanical damage to string tools or to the bit, and sub-optimal drilling performance. Matching of the bit and reamer to avoid these dysfunctions is not a simple process, and certainly is not resultant from simply having a similar cutter size in both cutting structures, or from compromising the rate of penetration potential of the bit.

There are four indices that substantially describe the performance of a bit and reamer system: Aggressivity; Stability; Durability; and Steerability. A tool that is capable of calculating the four indices for a bit and reamer allows optimal solutions to be developed for an application once the importance of the rankings are defined for that application. Accurate modeling of bit and reamer solutions must investigate the torque and weight balance in a number of different lithology scenarios. This must take into account the range of compressive strengths plus the type of transition encountered. Suitability of bits for specific reamers can be assessed using a sophisticated and novel reamer matcher tool. These can be tailored, via user input, to the specific parameters of the application. This matching tool uses logic tables based on theory, modeling, and field experience to provide a consistent, logical and quantitative approach to bit selection for reamers.

Case studies are presented from deepwater applications that clearly demonstrate the value of the use of indices and reamer matching tool. In combination, these have enabled high efficiency drilling performance, reducing cost per foot to the operator.
Geological Overview of the Middle Cretaceous Mishrif Formation in Abu Dhabi
Authors: Al-Zaabi Mohammed , Taher Ahmed , Azzam Ibrahim , Witte Johan
Published: February 2011

An extensive play review was carried out of the Mishrif Formation in Abu Dhabi. The database existed of almost 3000 2D seismic lines and 28 3D seismic surveys, complemented by 450 wells, out of which 260 had reliable time-depth data. The study resulted in Abu Dhabi-wide depth and thickness maps and a good overview of the Shilaif basin development and Mishrif reservoir distribution.

The Mishrif Formation in Abu Dhabi comprises the progradational shelf margin facies which is a time equivalent of the corresponding Shilaif basinal facies. The Mishrif development in the UAE is strongly asymmetric.

The western Mishrif platform sediments are characterized by stacked clinoforms comprising clean, high-energy carbonates. Rudist reefs and grainstone shoals along the successive shelf edges, which form those clinoforms, generally have good reservoir properties. Similar favorable reservoir characteristics can also be found in isolated platforms and grainstone beds which are locally well developed in lagoonal settings found behind the shelf edges.

In the east, the Mishrif is generally much thinner and is characterized by more differentiated, coarsening and shoaling-upwards sequences, each grading from fine basinal wackestone to medium/coarse-grained shallow marine packstone. This indicates sedimentation on a shallowing depositional slope. This slope lithofacies is made up of dark-colored, very fine- to fine-grained, well sorted, bioclastic packstones, grading into lighter colored, medium-grained, unsorted, bioclastic packstones to grainstones. High-quality reservoir facies occur only near the prograding shelf edges and over salt domes from which build-ups may have nucleated.

Kerogen carbon isotope values and GC-MS fingerprints confirm that the Shilaif Formation is the source of the Mishrif oils. The Shilaif Formation is immature over large parts of Abu Dhabi, notably the western offshore part of the Emirate. In the deeper salt-withdrawal basins such as the West Bu Hasa and Falaha synclines the source rock is oil-mature and also in the Oman Mountain foreland basin, grading to gas mature further towards the east. In most of the mature Shilaif kitchens, oil generation commenced during Miocene times, in the southern offshore part of Dubai it may have started as early as the Early Oligocene.

The Mishrif Play prospectivity evaluation will guide future appraisal drilling and will serve as a basis for further exploration activities related to conventional and unconventional trapping styles in the Formation.
We Need to Re-think the Acquisition and Processing Parameters for Sea Bottom Seismic in the Arabic Gulf
Authors: Berteussen Karl A. , Yuefeng Sun
Published: February 2011

Sea Bottom Acquisition is the standard seismic method for a large part of the Arabian Gulf. Typical for the region is shallow water and large velocity contrasts, i.e. high seismic velocity just below the sea bottom. This in essence represents a waveguide and has a very dominating effect on wave propagation and penetration. To understand the challenges and the opportunities this represent, we in this study are performing full acoustic and elastic modeling and then compare the predicted results with observed 4-component (4C) seismic data. We find that although the data is very complicated the simulations to a large extent can predict the observations. We thus conclude that the modern instruments as such are giving a correct picture of the wavefield and are not a part of the problem.

The simulation demonstrates that we should expect extremely strong Scholte waves which indeed also are observed. Because of the wave trapping mechanism mentioned above, these waves keep rolling for a very long time. The way most acquisition is done they represent a considerable noise problem not only for the actual shot but also for subsequent shots. In addition these waves are under-sampled in space with the present acquisition systems. This gives rise to high noise levels that are difficult to remove because it is aliased.

One positive opportunity is that we expect strong wave mode conversion to S-waves near the surface. We thus expect to see reflected S-waves in 4C data (S-down and S-up) if we record long enough. Modeling results also shows that they will have large variations with offset and basically are destroyed the way we typically process today. These waves might have important structural and lithological information if we can extract them properly.

In sum; the acquisition challenge will be to sample much denser in space as well as shooting with much longer time difference to avoid unacceptable left over noise from previous shots. Obviously that might have large cost effects, but also large upside with regard to survey quality. In addition to noise removal one of the processing challenges will be to use model dependent processing to enhance the information from both the P- and S- waves.
Overview of the Emerging Unconventional Oil and Gas Regulatory Framework in Quebec Vis-a-vis Its Western Canadian Counterparts
Authors: Paquet P. , Bews T. , Viala E. , Pearson M.
Published: February 2011

Western Canada has had a thriving conventional energy industry for many decades. It encompasses the exploration, development, transformation and transportation of hydrocarbons to markets across North America.

In Quebec, until recently the oil and gas industry was limited to distribution and transportation activities. As an industry, it regulated the infrastructure needed to process hydrocarbons and the legislation had very little to do with the exploration and development of hydrocarbons.

However, with shale gas development, technological breakthroughs, and more favourable pricing conditions, Quebec has witnessed the birth of an unconventional oil and gas industry which now includes intense activity by exploration companies, developers and possibly, over the next few years, producers.

The Western Canadian regulatory framework will be reviewed and contrasted with the emerging Quebec regulatory framework to highlight the different challenges that may arise.

We will outline the legislative framework that governs the unconventional oil and gas industry in Quebec. Also, we will address the potential liability of officers and directors regarding the reclamation and abandonment of upstream facilities.

We will comment on Quebec laws regulating land use, planning and the environment which may pose specific challenges depending on whether or not local gas lines, or processing plants need to be built or implemented.

The oil and gas industry in Quebec is made subject to mining laws that are not entirely compatible with industry practices of traditional players.

The regulation of unconventional oil and gas is emerging throughout North America.

In the St-Lawrence valley in the past 5 years, there has been a thriving exploration push. This exploration could lead in the medium to longer term to the securing of defined reserves for consumption in the local market. There had been anecdotal evidence of this over the years; however, recently this possibility has become very real indeed.

Millions of dollars had been invested over the years by local entities such as Petrolia and Gastem Inc. These juniors have partnered with western Canadian or American players which have confirmed their participation and are motivated to further exploration and development of shale gas discoveries and unconventional oil plays.
Geomodeling of Giant Carbonate Oilfields with a New Multipoint Statistics Workflow
Authors: Carrillat Alexis , Sharma Sachin Kumar , Grossmann Tino
Published: February 2011

Geomodeling is the integrating activity when developing a reservoir description. The static and dynamic models derived during geomodeling are vital in improving recovery, understanding the various uncertainties associated with it, and, ultimately, maximizing the profitability of any oilfield.

A case study of a giant heterogeneous carbonate brownfield is presented, in which the conceptual geological model built from detailed core analysis is used to drive the facies population during the geomodeling stage. Reservoir heterogeneity mapping is captured at different scales, from rock-types identified on core and advanced log analysis to joint stochastic inversion of reservoir properties derived from seismic prestack data.

A novel geomodeling workflow is presented to merge and optimize this set of multiscale data within a geological conceptual model using several geostatistical facies modeling schemes. Two of these are based on new technologies, namely truncated Gaussian simulation with 3D trend and multipoint geostatistics, which was developed to model complex geometries. The multipoint technique allows for more flexible integration of soft and hard data compared to traditional pixel- or object-based modeling approach.

The paper compares the two approaches and shows their respective advantages. It is the first time that the two new algorithms have been implemented in a giant carbonate oilfield. The outcome of the study shows that the new multipoint geostatistics facies simulation implementation performed a smooth integration of all available data. This included log data from several hundreds of wells, high-resolution seismic properties, and the conceptual geological model.
Production Monitoring and Optimization on a Mature Field
Authors: Tournier Emmanuel , Jaffres Benoit , Geoge Bina , Sabally Lamin
Published: February 2011

Mature fields require an efficient production monitoring in order to optimize the production. The use of several recovery techniques (water and gas injection) and lift methods are generating new challenges due to reservoir changes (high water cut and gas breakthrough). In order to relieve such challenges, with producers over 90% water cut and a great diversity of producing configurations: natural flowing, gas lifted and ESP driven wells, some tools based on commercial software have been implemented.

The global field potential and shortfalls are monitored on a daily basis, using the status of wells, the surface facilities constraints and well & field events.

The potential of each well is measured with two conventional production test separators and one multi-phase flow meter which allow monitoring closely the oil, water and gas flow rates in real time. The activity of both separators and multiphase flow meter is monitored every day in order to maximize their activity and detect anomalies which could impair the test quality and frequency. Dedicated tools have been developed and tuned for operated field & well configurations in order to follow-up in real time the well and gas-lift stability. The different customized tools implemented in this field allow reacting more efficiently in order to minimize the loss of production.

A full production network model, including the global outflow system based on well and surface parameters has been built. This model allows to compare production figures with predicted ones and therefore to identify more precisely the origin of production losses and the possible remedial solutions. Moreover, optimizations are performed on gas-lift injection target rates as well as on ESP’s frequencies on a daily basis.

Several critical scenarios of surface equipments failures are constantly tested and updated in order to provide to offshore team relevant solutions to lower impact on field production. The different scenarios simulated are taking into account production constraints: gas availability, water production & flaring limitation, shut-downs of critical surface equipments such as gas compressors.
A New Method of Average Pressure Estimation for a Horizontal Well in a Pattern Water Flooding System
Authors: Nomura M. , Al Dahmani Abdulla Rashed , Al Jawhari Mohamed Omar
Published: February 2011

Periodical PBU/PFO surveys have been conducted for monitoring horizontal wells and reservoir pressure maintenance in five-spot water flooding patterns in a giant carbonate reservoir located offshore Abu Dhabi. Although, in the literature, several methods have been proposed to estimate average pressure over a drainage area, none of such methods is applicable to the situation above where a flood pattern is confined with constant pressure boundaries. In this study, we propose a new method of average pressure estimation for a horizontal well in a drainage area associated with constant pressure boundaries. This new method was developed by creating a type curve representing a pressure correction against P* or an extended pressure as if an infinite reservoir existed. Although this method may look similar to the classical MBH theory, we can substantially differentiate the new method from the MBH method since the new method can handle both a horizontal well and a constant pressure boundary while the MBH method assumes a vertical well and a no-flow boundary alone. New pressure correction type curves were generated through intensive numerical simulations modeling a horizontal well in a square and rectangular drainage with a constant pressure boundary condition. The shape factors under a steady state condition were defined and calculated to characterize and differentiate the shape of individual type curves.
Maximizing Value of a Giant Offshore Asset through Proper Production Planning, Optimization and Capacity Management
Authors: Karim Amin Alaa Abdel , Al Zaabi Ahmed , Elamin Mohamed , Al Kiyoumi Ahmed , Tariq Syed M.
Published: February 2011

The fundamental objective of operators of oil and gas fields is to maximize hydrocarbon production from their assets safely, economically and without jeopardizing the ultimate recovery from the producing reservoir. It is a challenge to achieve this objective for a large, complex and dynamic system like the subject offshore field.

The production planning process is a key task within reservoir and production management to maximize production. Recognizing the importance of proper production planning and optimization, a dedicated team was formed in ZADCO in 2008 to enhance the work flow/process for production planning. In this paper, we present how the team modified the existing work flows/processes using a new string-by-string planning, optimization and monitoring tool to transform the existing reactive production planning procedures to a proactive and dynamic production planning process. The focus has been on integration of different components of the production optimization process and enhancing communication among all stakeholders. The new system allows for continuous monitoring of the planned vs. actual and facilitates quick adjustment of the forward plan to achieve the planned targets. The paper outlines how the integration of work processes between various disciplines is achieved so that decisions could be made with common view of the status and challenges ahead. New software tools, developed in house in ZADCO, help achieve this work flow in an efficient manner.

The new production planning system has been implemented in ZADCO since March, 2009. The results show better compliance with reservoir/shareholders guidelines, reduced response time, improved "what-if" abilities and faster decisionmaking to deal with complex situations. Although the system is in initial stages of implementation, it has already resulted in an improvement in the operational efficiency of ~3%, which translates into thousands of STBD per day of additional production availability for the field.
Independent Simultaneous Sources Seismic Acquisition in Libya - Full Scale Implementation and New Developments
Authors: Foster Mark , Howe Dave , Allen Tony , Buddery Dave , Jack Ian , Choi Albert
Published: February 2011

Howe (2008) has reported on a proof of concept of a new land seismic acquisition technique called Independent Simultaneous Sources. This paper describes a full scale implementation of this ISSTM method in Libya, where it is being used to acquire a very large exploration land seismic 3D survey in excess of 13,000 sq.kms

Recent developments in seismic recording systems allow for a recording spread to be continually active, which we refer to as continuous recording, although it may be more accurately described as recording of a set of contiguous records. This removes the necessity for real time synchronization of sources and recording systems. As long as the continuously recorded data and the source initiation can both be linked to the same time standard, (e.g. GPS time) the traditional shot records can be combed from the continuous dataset at any later stage. We have used the benefit of continuous recording to operate a large number of sources simultaneously on a large recording spread thereby greatly improving the productivity of land acquisition.

In this method all vibrators work independently without any attempt to synchronize their activity, and the underlying principle is that all interference between sources can be treated as ‘noise’. The noise is randomized as much as possible, and a standard suite of noise removal tools can be used during processing.

In our simple and robust approach, there is no apparent limit to the number of sources that can be operated simultaneously, there is no waiting time for any vibrator and very little central control or communication is required. It is very well suited for work in many environments including difficult terrain, where vibrator manoeuvering is slow, or where radio communication is challenged.

We demonstrate that this technique can deliver very high fold data at high efficiencies, such that it enables land 3D to be acquired for exploration purposes at costs comparable to marine exploration surveys.

We also report the initial results from field trials of a cable-less node recording system which, when combined with the efficiency of ISS, has the potential to change the way land seismic crews are configured and operated.
Wellbore Segmentation using Inflow Control Devices: Design and Optimisation Process
Authors: Al Marzooqi Ayesha , Helmy Hamdy , Keshka Ashraf , Elasmar Magdi , Shafia Shaiful
Published: February 2011

Inflow Control Devices (ICD) optimize production, delay water influx, eliminate / minimize annular flow, and ensure a uniform inflow along the horizontal wellbore at the cost of a small pressure drop. ICDs have brought promises to the industry’s efforts in horizontal wells inflow profile optimization which contributes to the economic success of horizontal wells.

Although the structure of different types of ICD varies from one design to another, the principle is the same - restrict flow, and therefore balance or equalize wellbore pressure drop to achieve an evenly distributed flow profile. In general ICD’s are not adjustable once installed in the well. The location of the device and the relationship between rate and pressure drop are fixed. This makes the design of a well completion and inflow control devices critical for production. Having knowledge of the pressure profile of a horizontal well, the ICD completion can be designed to achieve the required uniform influx. Therefore, the need for pressure profile prediction along horizontal wells’ inflow area is obvious. Reservoir conditions are dynamic during the wells’ life cycle; hence the impact of ICD varies over time.

Results to date within one of the onshore fields located in Abu Dhabi showed remarkable improvement in well performance, where gains in oil production with controlled water production have been achieved. Long-term reservoir simulation results also showed considerable recovery increase with ICD’s compared to the open-hole case.

The paper provides an integrated analysis method of dynamic inflow and outflow to generate the flow profile of a horizontal well. The additional frictional pressure drop created by inflow control devices is considered. Two conditions that result in production challenges, wellbore pressure drop and breakthrough of undesirable fluids are addressed. The focus will be on when and how water encroachment will hit the horizontal well bore and how inflow control devices will act to optimize production. A simulated example at field conditions will be used to illustrate that it is critical to understand the reservoir conditions and wellbore dynamics together when designing a completion with inflow control devices. Uncertainties in reservoir conditions are considered, and a business case for a passive shut-off ICD is discussed through cumulative oil gain predicted by simulation of different development options and completion design strategy.

This paper presents the evaluation and results of ICD technology, and how it is expected to become a game changer in this field development.
Optimum Separation Pressure for Heavy Oils Sequential Separation
Authors: AL-Jawad Mohammed S. , Hassan Omar F.
Published: February 2011

The estimation of quantity of liquid that is collected from gas/oil separation system is a very complex task because it requires the application of the flash calculations which needs to solve the cubic equation of state and to use some numerical techniques. These difficulties can be overcome by a computer model which requires a lot of experimental data, long time, and experience.

This paper adopts a new technique to simplify this problem. It suggests new correlations for optimum separator pressure for separation station of heavy oils. The correlations have been achieved for two- and three- stage separation systems.

The correlations have been created depending on many Iraqi oil samples. The optimum separator pressure of each individual separator was found at the maximum amount of liquid recovered with the minimum oil formation volume factor.

The Optimum Separator Soave – Redlich – Kwong model (OSSRK) has been adopted to estimate the optimum separator pressure, while the objective functions, like oil formation volume factor, are predicted by Separator Flash Soave – Redlich – Kwong model (SFSRK) (Hassan 2004).

The optimum separator pressures have been correlated with mole percent of hexane plus in the well stream fluid, mole percent of methane in the well stream fluid, temperature of the separator and the optimum pressure of the previous separator. Nonlinear multiple regression analysis has been applied to get the best correlation for each system.

Many statistical tests are used to check the validity of the proposed correlations.

The error percents of API, GOR, Bo between the optimal cases for each model and the relevant correlations show a maximum of 0.047%, 0.3% and 0.15% for two – stage systems, and 0.2%, 0.6% and 0.22% for three – stage systems. Also the cross plot method is applied to test the correlation validity. These checks are good indication to use these correlations with high degree of confidence.
Improving Well Completion via Real-Time Microseismic Monitoring: A West Texas Case Study
Authors: Ejofodomi E.A. , Yates M.E. , Downie R. , Itibrout T. , Catoi O.A.
Published: February 2011

This paper presents a case history of hydraulic fracture stimulation treatments performed on a vertical well completion in the Spraberry-Wolfcamp formations located in Midland County, Texas, in which real-time microseismic Hydraulic Fracture Monitoring (HFM) was utilized to “track” the development of the hydraulic fracture as it propagates through the formation thereby allowing for the implementation of corrective actions to improve the completion efficiency of the well.

The case history is presented in three main themes or sections: background, job execution, and post-job evaluation. The background section will provide an overview of the completion design as well as the HFM setup. The job execution section will then address how the real-time HFM observations and interpretations made during the treatment executions were used to identify undesired height growth, which prompted swift and concise actions to optimize the well completion by modifying the perforation scheme and treatment design. Finally the paper will present the results of the integrated HFM post-treatment evaluation and will discuss the observed differences between the planned and actual fracture geometries as observed from the microseismic monitoring results. Comparison of the microseismic fracture geometry to the anticipated fracture geometry showed that even in areas where we think that there might not be anything new to be learned, opportunities exist to apply new technology that can identify some of the complications and challenges involved, improve the success of stimulation treatments, and identify opportunities to improve operational efficiency.

Overall, this example clearly shows how real-time microseismic monitoring provides the data required to improve fracture modeling, identify fracture behavior that is not predictable by conventional means alone, and reveals several opportunities to improve completion efficiency.