bluuebunny/crossref_metadata_2025 huggingface dataset:
Production Optimization and Zonal Allocation for Auto Gas Lift Wells: A Case Study from Oman
Authors: Al-Ruheili Sharifa , Angelatos Mathew , Nair Sujith , Peringod Chandran , Sonti Kartik , Karacali Ozgur
Published: November 2012

In Auto gas-lifted wells, gas from either a gas zone or gas cap is used to lift oil in a commingled way. Balancing gas zone energy depletion to the benefit of oil production requires an accurate understanding of zonal contribution and an ability to adjust and control inflow from both zones.

A project was undertaken for accurate zonal allocation and optimization of lift gas rates by designing an appropriate zonal contribution measurement procedure for five Auto gas-lifted wells on two fields. This approach utilized both production logging and production testing to obtain both zonal down hole and commingled surface flow measurements. As a result of the exercise, lift gas flow into the tubing was optimized, thus maximizing the oil production rate while conserving reservoir energy through efficient gas usage.

Measurement of zonal contributions in multi-zone intelligent well completions are often challenging due to the complex nature of fluid flow under varying dynamic conditions of multiple reservoirs. This paper will explain the zonal contribution measurement program design, implementation, interpretation of data and lessons learnt from the project.
Trial of Multiphase Flow Meters for Remote Well Head Towers
Authors: Challa Raj Sekhar , Ismail Jawed , Karim Amin Alaa Abdel
Published: November 2012

Well testing on remote unmanned wellhead platforms (WHPTs), especially those with marginal wells is a challenge. On some of these remote WHPTs, currently well testing is done using a test separator installed on a supply boat. This method of testing the wells involves lot of manual intervention and is a time consuming activity with various activities which are sometime quite hazardous. In view of new field developments plans to increase production and to have more frequent and longer duration testing, an initiative was taken to look at the option of installing multiphase flow meters (MPFMs) on such well head towers which do not have well testing facilities. Accordingly, one MPFM each was installed on separate WHPTs.

By installing the MPFMs, ZADCO is now able to test these wells more frequently and for longer durations.These trial installations have been very successful as verified by the comparison of test results of the MPFM vs. Test Boat vs. Reservoir simulations. The success is not only in terms of testing but also proved beneficial in terms of saved man-hours and increased safety. Safety is increased and man-hours spent are reduced by avoiding all theconection / disconnection oftemporary manual piping from the boat to the well head tower.

This has encouraged ZADCO to embark on an exercise to install MPFMs on all those WHPTs which do not have a test separator and also to install MPFMs on those WHPTs where the existing test separators have become undersized due to the increase in production profile.

This trial use of MPFM in addition to providing very satisfactory test results in line with ZADCO testing requirements also has benefitted in various other ways as follows:

The need for frequent visit of test boat to the WHPTs is reduced. Carry testing more often thereby eliminating various factors related to weather, safety, unstable operation, etc. Longer duration of testing is facilitated for the wells; Increased safe operations by avoiding all the temporary piping from the boat to the well head tower which involves lot of lifting activities. There is also a huge saving in the man-hours spent in testing activities utilizing the boat. Thesesaved man-hours have also helped in effective utilisation of manpower.
SUBSEA PEC: The NDT Diverless Robotic System for the Pipeline Corrosion Inspection
Authors: Slomp E. , Bertelli M. , Milijanovic D.
Published: November 2012

PEC (Pulsed Eddy Current) is an NDT system applied to many sectors, and nowadays it plays an increasingly significant role in the maintenance of the offshore structures. The operational principle is based on eddy currents created by a magnetic field induced in a metal structure.

Through the reverse principle it is possible to analyze their behavior: we obtain information related to the average wall thickness and therefore of the corrosion status. Salient feature of PEC system is that it operates without removing, modifying or pre-treating the protective coating of the steel structure to be inspected.

The physical human presence for the system utilization has been essential in the standard practice. In the offshore world this requirement is very expensive, risky to comply with and often even physically impossible to achieve. For these cases, the subsea technology has allowed developing systems aiming to replace the human presence if this is not achievable or economically not viable. The "Subsea PEC" technology has been strategically developed for deep offshore inspections; a completely diverless machine mounted on WROV is deployed on the pipeline. The machine operations are remotely controlled from the surface on board the vessel and underwater module is employed on the pipe. The system automatically performs all the placements along the pipe length in order to carry out sectional scanning and obtain corrosion status readings around entire pipe perimeter (360degree readings). A single placement of the system allows detailed scan around the targeted pipe section and includes inspection of one further meter in length along the pipe. This technology allows complete mapping of the pipeline corrosion status without production interruptions since no destruction or pre-treatment of the protective coatings is required. Subsea PEC has already achieved considerable success with encouraging results during inspections carried out in the Mediterranean Sea, Red Sea, the South China Sea and the North Sea.
Subsurface Uncertainty Assessment for a New Carbonate Field Development
Authors: Ouezzani Mohammed Ridha , Belery Paul , El-Kassawneh Reyad , Daify Hossam , Ishiyama Tomohide , Yoshida Koichi , Zidan Maher
Published: November 2012

The objective of this paper is to present an integrated approach to quantify subsurface uncertainties and to share the assessments that have been applied in the subsurface studies of a new offshore oil field development in United Arab Emirates.

A methodology was developed to review and rank the various subsurface uncertainties. Seismic and geological tools were used to assess uncertainties of static parameters, while integration of all uncertainties was made in the dynamic simulation model.

New approaches were implemented to address two important parameters: Critical Water Saturation and Permeability. Critical Water Saturation uncertainty was derived by history matching production test data using a Saturation-Versus-Height model coupled with a Fractional Flow equation. For estimating uncertainty on Permeability, correlations with core derived fracture densities were developed.

Uncertainty on the Critical Water Saturation was found to have the highest impact on oil recovery. This uncertainty is related to an observation already made for other carbonate reservoirs where perforated intervals are sometimes producing at very low water-cut in spite of high water saturations interpreted from the logs.

This uncertainty review allowed updating the Dynamic Model with more robust P50 estimates of its parameters. The updated model was used to define a new base case development well scheme and production profile.

The study was important in maturing the development studies further. It was used in particular not only for updating the Dynamic Model, but also for defining future studies, preparing a data acquisition plan, and identifying mitigation actions to reduce the subsurface risks.
Case Study: New Approach of Chemical Implementation to Improve Oil Recovery and Production for Tight Carbonate Reservoir in Sungai Lilin
Authors: Nugroho Wisnu , Saputro Gunawan , Mucharam Leksono
Published: November 2012

Sugai Lilin oil field, located on the northeast flank of the South Sumatra basin. In 1933, operated by BPM, a discovery well (SLL-1) encountered productive Upper Talang Akar Sandstone which yielded 1365 BOPD with 0.219 MMSCFD gas from DST-1 and 1975 BOPD with 0.375 MMSCFD gas from DST-4. This field consists of two formation rock i.e. Talang Akar (sandstone, TAF) and Batu Raja (Limestone, BRF), both formations contain oil deposit with relatively small gas.

Depth of the top reservoir sandstone is about -775 m, with original pressure and temperature were 1294 psia and 78 C, respectively. Since 1934, this field started to produce oil from both formations, TAF and BRF. However, significant oil production rate of this field started in 1984, where the peak oil production rate reached 1800 bopd. The oil production drop very sharply to about 100 bopd with high water cut, in 2007.

From recent laboratorium EOR study, it showed that oil reservoir system in Baturaja limestone reservoir is considered as a strong oil wetting, especially in low permeability layer. This penomenon was also shown by value of the SOR which is greater than 35 %. In this kind of reservoir system, displacement by water will not result in increasing RF significantly, even viscosity of the oil is considered low. To improve oil production and oil recovery factor in this reservoir requires chemical injection which is able to alter the oil wetting to become non oil wetting system where the oil phase will flow much easily to. the wellbore. Using chemical solution of SEMAR, Huff n Puff approach has been implemented in ten (10) production wells in this Sungai Lilin Field. In this case, 3000 bbls of SEMAR solution with 2 % concentration was injected to each well, with 7 days of soaking. Responds of these huff and puff implementation varied among those wells, ranging from 50% to 400% increase in production peak.
Geometry of Porosity Break Plane Associated with Bitumen Zone and Timing of its Generation in an Upper Jurassic Reservoir, Offshore Abu Dhabi, UAE
Authors: Kojima Haruo , Shibasaki Toshiaki , Inoue Hiroyuki , Al Ameri Mohamed B.
Published: November 2012

An Upper Jurassic reservoir in "Field A" is characterized by existence of bitumen (tar mat) zone intersecting sublayers in the reservoir and porosity deterioration is observed in the bitumen zone and below bitumen zone. It is obvious that porosity deteriorates significantly at top of the bitumen (Porosity Break Plane: PBP) on core materials and open hole log interpretation, in addition, no flow contribution below PBP was confirmed by production logging data due to its tight nature. Therefore, it is very important to define PBP precisely in order to estimate hydrocarbon reserves and optimize future infill well locations.

The thickness of porous interval between top of reservoir and PBP indicates thinning toward the flank area and finally pinching-out in the flank area. The PBP and bitumen have been considered that they were possibly formed near paleo-OWC and the present curved shape of PBP can be attributed structural growth of the field after formation of them by deeper salt swelling.

PBP is confirmed at crest and flank wells in different stratigraphic position depending on their structural locations. Based on the detailed structural interpretation of the top reservoir using recently acquired 3D seismic data, the relationship between the top reservoir depth structure and PBP identified in the wells became clear. It is helpful for the PBP mapping and understanding of the bitumen distribution.

3D geological model incorporating PBP was constructed based on the above observation and new structure map derived from 3D seismic interpretation. This workflow helps to improve predictive capability on PBP mapping in non-well control. In addition, based on the structural interpretation of overburden horizons on the 3D seismic data and newly interpreted PBP, the history of structural development and timing of PBP generation were estimated. Based on the back stripping of overburden formations, PBP seems to be flatten in the Shilaif age. This paper discusses the reasonability of this timing.
Permeability Model Conditioning of a Thin, Heterogeneous High-K Dolomitized Unit in a Supergiant Carbonate Field, Offshore Abu Dhabi
Authors: Yamamoto K. , Kompanik G. , Brantferger K. , Al-Zinati O. , Ottinger G. , Al-Ali A. , Dodge S. , Edwards E.
Published: November 2012

This paper presents a method to condition the permeability modeling of a thin, heterogeneous high-K dolomitized unit. The interval is an important drilling target for field development, so precise permeability modeling is required to optimize well placement and completion designs in order to maximize oil recovery and minimize early water breakthrough.

Detailed core observations from 85 wells classify the unit into two groups: Group A, composed mainly of dolostone and Group B, comprised exclusively of calcareous dolostone. Regression analyses of plug porosity-permeability values are characterized by one regression line for each group by which dolostone represents a higher permeability trend relative to calcareous dolostone. Core-plug scaling is used to scale-up the porosity-permeability relationships from core plug- to modelscale (100 m by 100 m cells). The two regression lines accurately capture the permeability contrast within the dolomitized unit.

To extend the method into a full-field model, it is necessary to calibrate the well logs to the core data. Comparison of cores with various log responses indicates the porosity log is the most useful tool to achieve this. Group A, characterized by higher dolomite content, is distinguished by a distinct decrease in the porosity due to progressive dolomitization.

Porosity logs from 499 wells are interpreted and permeability values are assigned using the regression lines based on the detailed distribution map of both groups. The modeling approach using hundreds of well logs calibrated to cores yields a more detailed picture of the spatial permeability variations of the dolomitized unit. Dynamic data from ongoing history matching is also used to implicitly adjust the first-pass static model.
Application of pressure/fluid sampling measurement for the understanding of the complex fluid movement and communication in a mature, carbonate, heterogeneous reservoir
Authors: Al Mentheri Khawla , Ghalem Salim , Kaouche Salim , Keshtta Osama Mohamed , Al-Mutwali Omar , Shabaan Elbesaily
Published: November 2012

The lower cretaceous Formation reservoirs in Offshore Abu Dhabi represent a regressive cycles of sedimentation developed with shoal, laggonal, subtidal and supratidal sediments. This formation includes various types of lithologies along the reservoir column: Anhydrite alternating with Dolomites, limestone.

In such mature, heterogeneous oil reservoirs with a large gas cap, information may improve cost effective productivity, reduce the risks and improve the oil recovery. Special analysis of pressure measurement, fluid scanning and sampling while drilling is important to challenge open hole log saturation, to understand the behavior of each layer in the reservoir, to assess the communication between the sub layers, and to enhance the development schemes.

This study is a synthesis of all the Open-hole Vertical Pressure Profiling data sush as formation evaluation and sampling that has been performed through the history of the fields.

Investigations have been conducted on the identification of the in-situ reservoir fluid nature; the hydraulic vertical communication between layers; pressure maintenance mechanisms effect and pressure evolution through time and its link with lateral communication.

Furthermore from operational point of view best practices have been developed for a safe and efficient procedure in terms of data acquisition and analysis with the limitations of the formation testing tool.
Challenges and Key Learning for Developing Tight Carbonate Reservoirs
Authors: George Bovan K , Clara Cedric , Al Mazrooei Suhaila , Manseur Saadi , Abdou Medhat , Chong Tee Sin , Al Raeesi Muna
Published: November 2012

Fast track development projects, with timely data acquisition plans for development optimization, are very challenging for tight and heterogeneous carbonate reservoirs. This paper presents the challenges and key learning from initial stages of reservoir development with limited available data. Focus of this study is several stacked carbonate reservoirs in a giant field located in onshore Abu Dhabi. These undeveloped lower cretaceous reservoirs consist of porous sediments inter-bedded with dense layers deposited in a near shore lagoonal environment. The average permeability of these reservoirs is in the range of 0.5-5 md.

Mapping the static properties of these reservoirs is difficult since they are not resolved on seismic due to the low acoustic impedance contrast with adjacent dense layers. Petrophysical evaluation of thin porous bodies inter-bedded with dense layers in highly deviated wells pose significant challenges. Laterolog type LWD resistivity measurements which are less affected by environmental effects, offer more accurate formation resistivity compared to propagation type measurements. With limited suite of logs, some of the zones with complex lithology had to be evaluated innovatively as detailed in the paper. Integrated studies are initiated to improve reservoir description by carrying out accurate permeability mapping, SCAL, geomechanical and diagenesis & rock typing studies.

Significant challenges exist regarding the development of thin, tight and highly heterogeneous reservoirs, in terms of recovery mechanism, well architecture, well count, drilling, well completion and economics. Static and dynamic models were used extensively to evaluate different development scenarios and conduct sensitivity studies to bracket uncertainties. Various geo-steering options were discussed and the paper also details maximizing the reservoir productivity using long reach MRC (Maximum Reservoir Contact) wells.

Tight and heterogeneous reservoirs call for extensive and real time reservoir surveillance activities to assess well performance and reservoir connectivity. This paper highlights how these challenges are overcome through upfront surveillance planning and proactive well completion strategy.
An Integrated Multi-disciplinary Approach to Enhance Confidence in Development of a Tight Heterogeneous Reservoir
Authors: Nakamura Shinichi , AlHabshi Ali , Hussain Ali , Khalil Ashaf , AlBlooshi Jamal
Published: November 2012

This paper covers the integrated approach performed in one of the major oil fields in off-shore Abu Dhabi to increase the confidence level in this tight heterogeneous reservoir development.

This paper outlines the challenges that were faced along with the history of this field and the different approaches made by the development team to overcome them. The paper discusses the steps that the team went through in a period of ten weeks in order to come up in the end with an optimized subsurface & completion strategy plan. It shows how the reservoir with three main reservoir subzones is divided into 43 layers based on the sequence stratigraphy approach. It also discusses how the new infill well locations were optimized and designed with a fit-for-purpose completion strategy.

The paper will present the final outcomes of this review, the opportunities identified and the latest results obtained from the more confident post optimized development plan.
High Precision Monitoring of Crude Oil Storage
Authors: Al Muhairi Mohammed Bin , Al Zaabi Mohammed Abdulla
Published: November 2012

High Precision Monitoring of Crude Oil Tanks is very precise and accurate dynamic measurement detecting any Leak during operations. For many decades, the oil industry has been concerned with the financial consequences of oil losses. In recent years, there has also been an increased awareness of the industry's environmental impact. Pollution, caused both by liquid spills and atmospheric emissions, is an area of increased concern, and the industry has initiated programs to reduce the risks of environmental damage. Maintaining an accurate leak detection and reconciliation program is a necessity for anyone environmentally conscious such as a tank farm owner.

This paper describes the innovative solution developed by ZADCO maintenance team for High Precision Monitoring of Crude Oil Tanks system. It also describes the existing Crude Oil storage system hydraulics, technology of level storage tank measurements and control system utilized in developing the High Precision Monitoring logic algorithm. It shows relatively preciseness if the developed solution and the control on the different operations modes and scenarios. The solution became an online dynamic diagnostic and alerts the operators if unpleasant or abnormal operations accur in a time span of 27 seconds.
Safety Culture Study to Improve Safety Performance in Organization
Authors: Aryaguna A. , Argubie B. , Venema W. , Budiman A. , Djunaidi Z. , Kusminanti Y. , Erwandi D.
Published: November 2012

Safety Culture describes the enduring value and priority placed on worker and public safety by everyone in every group at every level of an organization. It is the result of individual and group values, attitudes and beliefs, competencies and patterns of behavior that determine the style and proficiency of the health and safety management in organization.

In recent years, many organizations are showing interest in "Safety Culture" as a means to reduce the high potential incidents, as well as the inherent risks associated with.

TOTAL E&P Indonesie (TEPI) conducted Safety Culture studies based on three main approaches, the Safety Climate Level (SCL), Safety Culture Maturity Level (SCML) and Culture Based Safety (CBS). SCL captures the safety perception within the employees. SCML measures the maturity of the organizational behaviors, which is developed to assist safety improvement processes. The CBS is the model to develop safety norms among workers community through 2 (two) variables: leadership, workers’ empowerment and involvement.

This paper will only focus on the results from the SCML approach that was done in 2005, 2007, and 2010. Based on the studies that was conducted in the mentioned years, the result shows the improvement of Safety Culture values in TEPI and the consistency in accident reduction and control result. The latest study in 2010 shows that TEPI is in the level between 4 and 5, with average score 4.27 (in a scale of 5).

The levels show that TEPI is already in the right track. Rooms for improvements were identified from these studies and action plans are always prepared and implemented in order to have continuous improvement in organization's Safety Culture and performance.

This paper will also analyze the trend analysis between the SCML study results with the safety programs that TEPI has done along the years, safety performances of TEPI, and the Health Safety & Environment Management System (HSE-MS) Implementation.
Integration of Subsurface Data, Modern Analog Concepts, and History Matching Feedback to Model a Thick Carbonate Reservoir, Offshore Abu Dhabi
Authors: Ottinger G. , Kompanik G. , Al Suwaidi M. , Brantferger K. , Edwards H.
Published: November 2012

Sustaining hydrocarbon production to meet growing energy demand is an industry-wide challenge, especially for Middle East projects. Consequently the need for sound, robust models is increasingly important to accurately represent the subsurface ahead of field development/production. A common hurdle to overcome involves scaling core-based geologic characterization to models, such as representing thin high perm streaks or populating facies mosaics. This paper summarizes the approach used to characterize and model a thick carbonate reservoir from a giant offshore Abu Dhabi oil field.

Core descriptions from 36 key wells across the field establish the setting as a structurally modified ramp characterized by patchy facies distributions that was frequently reworked by storms. Core:log calibration was investigated but deemed not applicable for this reservoir, thus core was the primary control on the rock type model. High permeability grainstones and algal/rudist floatstone interpreted as storm deposits are thin (<1 foot) and not correlative between cored wells. The wells were rock typed and mapped to reveal trends between rock types, thickness and reservoir quality.

These trends were integrated with previous learnings and modern analogs to help bridge between the core and model scales, such as for geobody dimensions and spatial variability within the model. Deterministically-guided stochastic distribution of rock types using Truncated Gaussian Simulation was the preferred method to build the rock type model based on data coverage and the vertical stack of facies observed in core. Fine-scale layering in certain zones of the geomodel was necessary to capture the thin high perm streaks. This necessity led to coarser model layers, where applicable, to maintain a manageable geomodel size. Distribution and connectivity of high perm geobodies were guided by multiple feedback iterations from history matched results. These iterations were key to achieve a sound, robust model.
3D Seismic Survey Design Using Point Sources and Point Receivers: A Case Study from the Uae Thrustbelt Region
Authors: van Baaren Peter , May Roger , Zarkhidze Alexander , Morrison David , Quigley John , Al Qadi Abdulla
Published: November 2012

Abstract Summary

In this paper we describe an integrated design of the acquisition parameters for a 3D seismic survey in a difficult geological and logistical environment using an ultra-high channel count point receiver recording system, productivity enhancement techniques and incorporating advanced processing tools. Advances in acquisition hardware and techniques change the way seismic surveys are designed. These advances include continuous recording, faster computers that allow running more elaborate algorithms, and new methods such as surface wave methods to model and subtract aliased groundroll. These new tools require different input data and different sampling. How these advances influence the design process is illustrated using a case study for a 3D survey acquired in the 3rd quarter of 2011 located in the largely sand covered thrustbelt area of the United Arab Emirates.

The seismic data were acquired using a high productivity technique that uses time and distance rules coupled with integrated QC rules based on active spread criteria to maximize productivity and minimize cross-talk between the individual seismic sources. The initial data from the 3D survey shows that the proposed integrated 3D survey design is adequate for coherent noise attenuation, source cross-talk removal and building a near-surface model.
Alkali Surfactant Gas Injection: Attractive Laboratory Results Under the Harsh Salinity and Temperature Conditions of Middle East Carbonates
Authors: Cottin C. , Morel D. , Levitt D. , Cordelier P. , Pope G.
Published: November 2012

Alkali-surfactant-polymer (ASP) injection is an attractive enhanced oil recovery (EOR) technique that allows achieving almost zero residual oil saturation at the microscopic scale when well designed. In this combination of chemicals, the role of polymer is to achieve the necessary mobility control of the microemulsion / oil fronts which are formed and propagated through the reservoir. Foam has been recently identified as an alternative to polymer to achieve such mobility control.

This paper describes the alkali-surfactant-gas (ASG) and surfactant-gas (SG) laboratory results which have been obtained on carbonate core samples under harsh salinity (~230 g/L) and temperature (83°C) conditions representative of some Middle East reservoirs.

The starting point was the development of a surfactant formulation to achieve ultra-low interfacial tension between the oil and injected solution in these particular salinity and temperature conditions, using the classical microemulsion phase behavior approach. This formulation used a class of surfactants newly developed at The University of Texas at Austin (UTA), compatible with and without divalent ions.

The efficiency (in terms of oil recovery) of this chemical formulation was demonstrated with SP core floods. The same chemical formulation was used for SG as the starting point, and was further enhanced; the polymer was replaced by nitrogen or methane co-injected with surfactant to create foam.

Extensive studies of the ASG process have been performed. This includes phase behavior with and without alkali, screening laboratory studies to pre-select the surfactant with adequate foam properties, and carbonate coreflood experiments to measure the residual oil saturation to SG injection, including the consumption of chemicals. There is still room for optimization, but very promising results have already been obtained on that particular case leading to high recovery of the remaining oil after waterflood.
Application of Advanced Analysis Techniques for Waterflood Management: A Case Study in a Large Heterogeneous Carbonate Reservoir
Authors: Al Henshiri M. Yousef , Tariq Syed
Published: November 2012

Literature is replete with numerous techniques for waterflood analysis developed over the last four decades. Most of these techniques are in the form of simple diagnostic plots based on available production/injection and pressure data routinely gathered in the field.

This paper illustrates a systematic methodology that integrates various diagnostic plots at field, sector, pattern and well levels. It shows the interaction between these levels and how the integration of different diagnostic techniques are key to better understand the dynamics of waterflood performance and for identification of performance improvement opportunities. The techniques presented in this paper were applied to evaluate the waterflood performance & efficiency, to identify anomalous performances, to detect production and injection problems, to establish water production mechanism, and to assess impact of reservoir heterogeneities in a giant carbonate reservoir located in the Arabian Gulf. The subject reservoir has been producing under a large scale pattern waterflood for over 30 years.

The construction and uses of various diagnostic plots for quantitative assessment of the waterflood performance are presented in this paper. As a first step, the historical performance plots are used to evaluate the maturity of water production and to provide an indication of the sweep and recovery efficiency. The voidage replacement ratio (VRR) when integrated with historical pressure profiles and material balance plots provides critical information on the reservoir pressurization process. The water breakthrough time and the WOR trends are then used in evaluating the water production mechanism and in assessing the reservoir heterogeneity. Production logs (PLT, WFL, PNC, CHFR and RST) provide key information for monitoring and evaluating vertical and areal sweep in the reservoir. Hall plots provide information regarding the injection well performance and related dynamics.

The approach presented above led to significant enhancement in understanding the displacement process and water movement within the reservoir. The integrated analysis resulted in improvements in the field practices for reservoir management and well completion design for future development wells.
Extended Reach Horizontal Accessibility for UAE Offshore
Authors: Issa Faiz , Jackson Alfred , Hudson Lisa
Published: November 2012

The UAE field has many thin multilayered carbonate reservoirs. Production from thse thin reservoirs are primarily supported by water injection. Reservoir properties, such as permeability, pore pressure, and water saturation, vary significantly both across the field geographically and within the different layers.

Recently a study has been done to drill and maximize reservoir contact via ERD wells. To reduce costs and improve recovery, further development of the plan is to use wells drilled with throws greater than 15,000 ft and measured depths greater than 20,000 ft with some wells exceeding 35,000 ft. Long horizontals provide many benefits including enhanced access to offshore reserves, optimized productivity, reduced capital expenditure, and a minimized environmental impact

With these benefits come challenges, accessibility for intervention operations being the most prevalent. Many factors affect the accessibility and intervention capabilities in ERD wells. Completion ID restrictions play a critical role in the equipment availability and selection. Once equipment is selected the leading principles used for improved access in ERD applications are:

Increasing pipe bending stiffness to postpone helical buckling Reducing Normal Force between the CT wellbore Reducing Friction Coefficient Adding Axial Forces

ERD applications and accessibility for interventions have been an ongoing challenge on how to properly model and predict the reach of CT in varying environments. The two pilot wells covered in this paper allowed for an array of information to be collected as the trajectories were very similar but the wells themselves were very unique. One well was a producer while the other was an injector. One well was completed with 13% Chromium and the other with conventional tubing.

In this paper we will cover the above topics in more detail to clearly outline the challenges of ERD operations and the methods to overcome them. It will be clearly outline how these methods were used on two ERD pilot wells in UAE with the supporting actual operational data. These wells and lessons learned will pave the way for future ERD operations planned in both offshore and island based offshore UAE pilot projects.
Optimization of CO2 WAG Processes in a Selected Carbonate Reservoir-An Experimental Approach
Authors: Amin Mohamed E. , Zekri Abdulrazag Y. , Almehaideb Reyadh , Al-Attar Hazim
Published: November 2012

Miscible gas flooding using carbon dioxide is currently being investigated as a possible EOR process for a number of United Arab Emirates (UAE) reservoirs. It has high potential to improve oil recovery in addition to possibly utilizing most of the carbon dioxide emissions from industrial sources. The major factors affecting implementation of CO2 floods are the availability of CO2 at economic prices (generally within 2-3 $/MSCF) and the net utilization ratio of CO2 per barrel of additional oil recovered. Typical net utilization of CO2 for well-designed floods vary from field to field but on average has been estimated at 5.5 MSCF CO2 per additional barrel of oil in a US EOR overview study by Broome et al.1 and between 4-6 MSCF/barrel by a more recent study by Jeschke et al.2. At other fields it might be as high as 15 MSCF/barrel or more. Minimizing net utilization requires controlling the high mobility ratio for miscible gas injection which causes lower sweep due to gas channeling and by-passing of the oil in the reservoir. To control the mobility ratio, the Water-Alternating CO2-Gas (WAG) technique is proposed by injecting alternately small solvent [CO2] and water slugs. The slug of water reduces the speed of the solvent and solvent fingering thus improving the mobility ratio of the injected fluids to fluids in place.

The objective of this work is to experimentally assess the recovery of oil with CO2 injection in a selected UAE carbonate reservoir. Two types of CO2-flooding experiments were conducted, continuous miscible CO2 injection and CO2-WAG injection using a specialized experimental rig. The effects of changing the CO2-Water ratio and WAG timing on the overall performance of the flood were investigated. All laboratory tests were conducted under controlled conditions of pressure and temperature corresponding to field conditions. Results of this laboratory investigation reveal a general trend of improved oil recovery with increased volume of CO2 inside core samples during the flood process. The observed ultimate oil recoveries range from 52 percent with continuous water injection to 72 percent of the original oil in place with continuous CO2 injection over the full period of the experiment with recoveries of the CO2-WAG floods falling in between. The optimum CO2-WAG ratio was found to occur at 1:2.

The outcomes of this work should contribute to our understanding of WAG CO2 floods for the UAE reservoirs and supports the ongoing R&D efforts made by the operating oil companies in the UAE towards application of CO2-WAG floods
Workplace monitoring in ADGAS - A step towards employee wellbeing
Authors: Sarkar Prabir , Al-Ali Asiyah , Roy Soumen , Zamzam Mohamed
Published: November 2012

ADGAS has undertaken a quantitative evaluation of the priority chemical hazards identified in its Occupational Health risk assessment study. The major hazards identified included; BTEX (Benzene, Toluene, Ethyl Benzene & Xylene), Hydrogen Sulphide, Welding fumes & paints containing di-isocyanates. In the Product Quality Department, exposure to BTEX and its metabolites & hydrogen sulphide were monitored for Product Analysts. Exposure to welding fume contaminants & particulates were monitored for welders and fabricators. Estimation of di-isocyanates exposure while performing painting operations was also carried out in the General Technical Services Department.

The quantification of occupational hazards was used to determine health risks from exposure to potentially hazardous substances. The data also served in the preparation of a structured occupational hygiene monitoring plan, as a follow-up to the recommendations of the Occupational Health Risk Assessment. Level of exposure to all the hazardous components were found to be well within the prescribed ACGIH threshold limit values, thus suggesting negligible levels of risk for the employees involved in the concerned operations.

Despite the low exposure levels, the workplace monitoring has led to a thorough evaluation and implementation of better work practices (E.g. mandatory use of Self Containing Breathing Apparatus for Product analysts, while sampling H2S) & conditions (E.g. balancing of fume hoods for improved capture of contaminants in the Product Quality Department) leading to a further minimization of health risks.

In the first place, the monitoring programme has enabled ADGAS to adhere to the ADNOC Code of Practice requirements. Secondly, this has been a step forward in ensuring the wellbeing of exposed working group and remaining in tune with the management commitment for the pursuit of higher HSE standards and ensuring higher productivity and employee satisfaction.
Integration of Drilling, Completion, and Stimulation Technology Boosts Saudi Arabian Gas Well Performance
Authors: Rahim Zillur , Al-Kanaan Adnan , Al-Anazi Hamoud , Al-Harbi Abdulaziz , Ginest Noel , Halim Abdul , Wilson Stuart , Johnston Bryan
Published: November 2012

Multistage stimulation of horizontal wells in tight gas carbonate formations in Saudi Arabia has been conducted since 2007. The production results from early completions showed significant improvements over conventional completion methods. As more wells were completed and more analyses conducted, it was observed that, although good fracture signatures were seen on the first fracturing stage, subsequent stages often showed no fracture signatures. Stage-by-stage testing confirmed that the greatest production came from the first stage and subsequent stages only added marginal contribution.

Initially, all of the horizontal wellbores in the RES formation carbonate reservoirs in which multistage fracturing (MSF) assemblies were deployed were drilled parallel to the direction of maximum or principal in-situ stress (σmax). This strategy was modified to drill wells parallel to the direction of minimum horizontal in-situ stress (σmin) to try to generate multiple transverse fractures. Since then, many wells drilled parallel to the σmin direction have been completed with MSF systems and fracturing treatments have been performed.

Drilling parallel to σmin is more challenging and requires careful consideration of mud weights to minimize formation breakout or breakdown. Likewise, deploying MSF systems in these wells is challenging since there are often fewer locations in which to place openhole packers due to potential borehole instability.

Presented in this paper are analyses of actual data from wells completed with MSF and hydraulically fractured. Unique fracture signatures confirmed that each stage was fractured, and subsequent production rates confirmed improved results. This paper will focus on the process of determining why it was necessary to change the drilling direction and how this strategy was implemented.
Maintenance Activity While the Wellhead Tower under Live Condition
Authors: Al Jabri A.
Published: November 2012

In response to the "Call for Proposal" for ADIPEC -2012, I'm pleased to submit a paper proposal for Managing Risk in Simultaneous Operations (SIMOPS) under Maintenance/Integrity/HSE/Operations Technical Categories for your consideration. Simultaneous Operation is defined as parallel operation of two or more activities e.g. drilling and production at the same time. Occurrence of this kind of operation exposes the parties to variety risks which due to their interaction. As a result parties before executing the activities meets and studies the mitigation factors taking into account ADMA-OPCO levels of safety.Considering a high production tower we utilize the full measures of SIMOPS. Nevertheless, this type of operation is not the case always for drilling. Maintenance campaigns were jobs under live conditions are executed, for that reason the oil tower needs to be shutdown and SIMOPS concept indeed essential to re-commission the tower.

Planning SIMOPS is time consuming due the measures needed to start such operation; the arrangements should contain F&G systems, Deluge system, production crew, panic bottoms on rig floor and the company representative beside other items. Finalizing the HSE audit takes more time. This measures delay the tower commission for a while accordingly losses in production occurs. Managing risks was excellent approach in making the SIMOPS operation much more efficient for our operation is profitable for the company I work for. The results were unprecedented indeed. We managed to shorten time of SIMOPS preparation, comply with the HSEQA regulation, reduce shutdown period of WHT accordingly gain more production, apply maintenance activities and reduce the time of the maintenance barge on-site. This technical paper will introduce our SIMOPS concept of managing risk during maintenance activities and present a case study of a similar case handled previously.
Feasibility Study of Miscible Gas Injection in a Carbonate Oil Reservoir; A Systematic Experimental and Simulation Approach
Authors: Kallehbasti Mehdi Alipour , Paroodbari Javad Rostami , Alizadeh Nasser , Ravari Reza Rostami , Amani Mahmood
Published: November 2012

Gas injection is a common practice in many carbonate oil fields; however, there is a lot of debate around the viability of economical enhanced oil recovery by miscible gas injection. For a correct simulation of miscible gas injection and monitoring the progress of the miscible front in the reservoir, a compositional reservoir simulation is needed. Fluid characterization is one of the most important parts of this simulation.

In this paper, fluid characterization for such a mechanism is discussed and a systematic approach is presented which could be used in any other similar study. The dynamic reservoir simulation is also brought at the end for comparison. The carbonate reservoir of the field of interest, contains 900 million barrels of under-saturated, 34 API degrees oil, with initial reservoir pressure of 8200 psi. After building a PVT model and adjusting the Equation of State (EOS), the Minimum Miscibility Pressure (MMP) of four different injection gases (N2, CO2, associated gas and sales gas) were calculated with different methods. Swelling test and slim tube test were also conducted which were used to cross check the EOS tuning. Although, MMPs in all cases were much lower than initial reservoir pressure, their effects on recovery factor were different. A compositional reservoir model was built based on the tuned EOS and the effects of all injection gases in different scenarios were examined. The procedures as well as the main results are explained in this paper.
LWD Resistivity Tool Application to Horizontal Geosteering in Thinly Bedded Carbonate Reservoir Layers
Authors: Obara Tomohiro , Yin Hezhu , Boyd Douglas , Yamamoto Kazuyuki
Published: November 2012

Logging While Drilling (LWD) propagation and azimuthal laterolog resistivity tools are utilized to accurately place long horizontal wells within a reservoir unit located near the base of a thick carbonate reservoir. The reservoir unit is comprised of a thin dolostone layer, sandwiched between two, moderately thicker limestone layers. The dolostone has higher resistivity than the two limestone layers. The degree of resistivity elevation varies laterally throughout the field depending on the degree of dolomitization, saturation and porosity levels. When adequate resistivity contrast between the limestones and dolostone exists, geosteering geologists utilize this contrast to direct the well in close proximity to or within the dolostone. This is the preferred method of geosteering in ZADCO for extended reach horizontals with its current drilling rig fleet, which are near their drilling reach capacity. This reduces the use of nuclear source porosity tools and the potential for long fishing operations should a stuck tool in hole incident occur. The history of the field development (e.g. water injection), simulation predictions of water front movement, geological characteristics, surveillance data and petrophysical data in the area of interest are checked to determine the suitability of resistivity tools (only) to geosteering.
Moving to New Technologies in Design Drafting and "As Building"
Authors: Krishnan Unni
Published: November 2012

Drawing is said to be the language of Engineers. In a simple drawing, we could depict what would require a thousand words to describe. No wonder why the technocrats always love to present their case with the aid of sketches and drawings.

In the olden days, technical concepts and ideas were transformed into paper using pencils and erasers and the media was tracing paper. It had the inherent disadvantage that pencil writings were getting smudged or erased with the passage of time and the tracing paper was getting torn or damaged. Gradually, the pencil leads gave way to ink; so also, the tracing paper was replaced with tracing films. Stencils with suitable size pens and drawing instruments like set squares, protractor, compass. French curve & dividers gradually became the order of the day. Drawing boards with fancy Tee squares started decorating the drafting offices. Quality improvements came to the fore, not just in presentation; but in productivity and storage of drawings.

During the Industrial Revolution, draftsmanship gradually became a specialized trade and drawing tables were considered an integral part of a Design or Engineering office. In those days, they were made of fine wood and brass; but slowly became more utilitarian and were built of steel and plastic.