bluuebunny/crossref_metadata_2025 huggingface dataset:
Enumeration Approach in Condensate Banking Study of Gas Condensate Reservoir
Authors: Fuad Iqmal Irsyad , Lee Jang Hyun , Akhir Nur Asyraf , Zulkifli Izzati
Published: November 2017

In this paper, enumeration method was developed to simulate gas condensate reservoir behavior based on the different condensate banking zones. Sharp increment of pressure drawdown near wellbore and description of condensate bank away the wellbore are still part of challenges in simulating gas condensate reservoir. This method allows prediction on how pressure behavior near and away wellbore and how the condensate banking will evolve in future due to the simultaneous flow of gas and condensate in the reservoir.

A single well model has been developed to investigate the effect of condensate bank on pressure behavior in gas condensate reservoir. Upon production, gas condensate reservoir creates different zones based on different phase mobility, resulting from condensate banking. Enumeration initialization approach is to divide the simulation explicitly for the multiple stages. During the stops, condensate bank parameters have been modified at each zone to describe drastic change of well performance due to condensate banking. A representative matured gas condensate reservoir from Malay Basin has been selected for the purpose. The effect of the mobility changes to pressure behavior is then investigated.

Comparison of pressure behavior between enumeration ways with conventional approach have been presented. It was found that enumeration method shows better prediction in investigating the pressure behavior and condensate saturation near and away wellbore during stabilized production. It is due to its ability to predict mobility changes at every zones. The change of relative permeability to variations in fluid saturation, velocity, and interfacial tension cause increment of pressure drawdown. In analytical analysis, the increment of pressure drawdown mostly demarcated as positive skin to a factor of 30 – 90. With enumeration method in place, pressure behavior can be quantified without defining the positive skin, thus improve the condensate bank characterization.

This paper improves accuracy in defining complex physics of condensate banking phenomena, also providing key tool in quantifying the condensate bank. Enumeration approach screens the potential condensate banking in later well life and appropriate mitigation technique can be selected – optimize drawdown or change wettability as the positive skin term in simulation has been replaced.
Integrated Workflow of GOR Management Towards Sustainable Oil Production
Authors: Sarsekov Arlen , Al Neaimi Ahmed , Saif Omar Yousef , Abed Abdalla
Published: November 2017

Most of the oil fields in Middle East are carbonate bearing rocks including onshore and offshore environment. GOR Management is critical aspect in light oil fields where strict guideline of GOR value can cause production losses.

Integrated GOR Management is a workflow of solutions of different techniques which can be applied in order to manage gas production and stay below SH's guideline.

Integrated GOR Management will consist of the following aspects: Reservoir dynamic analysis and water/gas injection balanceEfficient VRR calculation methodologyRigless intervention such as Gas shut off with chemicals and cement squeeze.New completion technologies which can delay Gas BreakthroughSurface facility optimization.

The Real case study has been applied in giant offshore carbonate field to manage GOR value and mitigate gas movement and balance injection/production offtake.

GOR management is a critical aspect in most of the field to maximize recovery factor. Most of the time this subject is treated as a single subsurface challenge; however integrated approach which takes into account subsurface and surface optimization, rig and rigless intervention can bring the tremendous value towards sustainable oil production.
Prediction of the CO2 Solubility in Deep Eutectic Solvents: A Comparative Study between PC-SAFT and Cubic Equations of State
Authors: Animasahun Olamide H. , Khan Muhammad N. , Peters Cor J.
Published: November 2017

For industrial post-combustion CO2 capture processes, deep eutectic solvents (DESs) have been identified as a viable replacement for the conventional amine-based counterpart. DESs are cheap to prepare and they are more environmental friendly, also in comparison with ionic liquids (ILs).

Although, several DESs have been tested for their CO2 absorption capacity, still there are a lot of DESs that are yet to be studied. This work focused on developing and comparing thermodynamic models (equation of states) for predicting vapor/liquid equilibria (VLE) of CO2/DES systems. With this approach, all the available DESs can be tested while limiting cost and time.

Peng-Robinson (PR), Soave-Redlich-Kwong (SRK) and Perturbed-Chain SAFT (PC-SAFT) equations of state were employed to predict the vapor/liquid equilibria of 75 different CO2/DES systems over a range of temperature and pressure conditions, comprising in total 562 data points. The algorithm was evaluated by first estimating the pure component properties of the DESs, followed by the model predictions, which turned out to be in close agreement with experimental measurements.

The results show that all the three EoS performed to a very high degree of accuracy. For eighty-one percent of the systems evaluated, both the Peng-Robinson and Soave-Redlich-Kwong EoS were able to predict the VLE with average deviation of less than 5% from the experimental data. Perturbed-Chain SAFT EoS predicts seventy-two percent of the systems with deviations of less than 5% from the literature values. It was also revealed that for some systems with CO2 composition less than 0.5% and at temperature below 293.15 K, the prediction capability of PC-SAFT reduced drastically.
Tensioned String Anodes for Cathodic Protection of Offshore Platforms
Authors: Tremolada Simone
Published: November 2017

Objectives/Scope

The retrofit of cathodic protection systems of offshore platform is crucial for the extension of existing oil and gas fields life in the present economic scenario of oil low pricing.

Tensioned string anodes is a reliable way to afford this problem in a fast and efficient way with CAPEX savings.

Methods, Procedures, Process

A real case of retrofit of 4 platforms in offshore West Africa is presented with focus on technical and economical aspects.

The technical review will cover the analysis of anodes and cables residual life after 18 years in operation in seawater as well as design and installation procedures.

The economical analysis is aimed to compare the costs for galvanic vs. impressed current cathodic protection for the retrofit of oil rigs CP systems in shallow and deep water in order to allow easier ROI analysis.

Results, Observations, Conclusions

The experiences gathered with different mixed metal oxide anodic structures provide the offshore oil and gas industry with valuable options for retrofits on platforms where cathodic protection systems need to be replaced or installed.

The reported case represents a significant experience of cathodic protection retrofitting of offshore platforms using the impressed current technique.

The Tensioned Anode String assembly allows for a versatile and flexible design, with installation costs quite competitive with respect to galvanic anodes system in water depth greater than 80m.

The 18+8 years of performance with the Tensioned Anode Strings, installed in 1987 and replaced in 2005, demonstrates the robustness of the system and the durability of all the components.

The laboratory investigations on the anodes recovered after 18 years of continuous service confirm the performance of the mixed metal oxide activated titanium anodes in sea water in line with the results extrapolated from accelerated life tests performed in the laboratories.

Novel/Additive Information

A complete review of state of the art technologies for impressed current cathodic protection systems for offshore platforms will complete the paper with highlights on the new progresses on installation in the Mediterranean Sea and offshore Brazil
Minimizing Production Losses through Effective Failure Analysis and Mitigation
Authors: Liu Zhenhai
Published: November 2017

Equipment failures, malfunction of protection devices, human errors, process upsets, etc. are the common causes for unplanned shutdowns. These unplanned trip events can lead to substantial production opportunity losses and impact company's profit. The requirements of outstanding performance forces companies to take effective measures in reducing plant downtime frequency and its consequential costs.

ADGAS operates three LNG trains and five gas treating plants on a remote Island. Due to its harsh operating environment, equipment aging, frequent change of feed gas conditions, etc., maintaining a reliable and stable operation has been very challenging. Since 1997 the accumulated production losses caused by unplanned shutdowns has reached few hundred million dollars. Among these losses, unplanned trips due to instrument and control failures have contributed to more than 20% of total production losses. Theses failures also resulted in increased flaring. Thus minimizing unscheduled plant downtime and improving the reliability of instrument devices is imperative both economically and environmentally.

This paper describes a three-track approach which implementation has led to 66% reduction on the number of unplanned trips caused by instrument failures.
Analysis of Wireless Data Transmission for the Site Survey of Telemetry Systems Projects
Authors: Aouadj M. , Sellami D. , Naceri F. , Aissi S.
Published: November 2017

This paper aim is to propose a radio transmission analysing method for the site survey of telemetry systems (e.g., SCADA: Supervisory Control And Data Acquisition), these systems are usually used to supervise remote process installations in large oil and gas fields. This method is presented over a software design and development which includes all radio propagation data and calculations, needed during the technical site survey phase of a telemetry system project execution. The approach is applied for the acquisition, control and online modeling of an oil collection pipeline network using a SCADA system.

The designed software we named "SCADA Radio Transmission," is to perform the radio propagation analysis. By introducing data (topographic coordinates, obstacles heights and characteristics data of the transmission equipment) it allows calculation of towers heights that ensure good radio clearance (Fresnel Zone), plot of the radio transmission link and to visulize results of the radio link budget. Complete calculations equations of this software are provided with detailed radio propagation analysis sample results of the studied oil collection pipeline network, to permit more comprehension for readers. The designed software role is to:

– determine the correct height of the towers by inserting the topographical data of the field, thus providing a radio clearance of the Fresnel first ellipsoid; – Draw up, for the established link, a link budget including the received signal power as well as the margin against the reception threshold; – In addition, this software allows the adjustment of the pylons heights in order to rectify any diffraction, due to bad visibility hop.

A case study application of this software is presented for the data acquisition, control and online modeling of an oil collection pipeline network at Hassi Messaoud oilfield.
Investigation of Dissolution Effects on Dolomite Porous Media under Carbonated Water Injection CWI
Authors: Nunez R. , Vaz R. G. , Koroishi E. T. , Vargas J. A. , Trevisan O. V.
Published: November 2017

To investigate the effects of carbonated water injection (CWI) on dolomite porous media, a set of two coreflooding experiments were performed on outcrop samples. The results allowed the identification of the effects of dissolution on porosity and permeability on outcrop dolomite samples. Experiments were carried out at 70 °C, injection pressures of 8500 and 7500 psi, and a constant injection flow rate of 2 cm3/min. The experimental setup was assembled and commissioned arranging two coreholders connected in series, each one containing a rock sample, to improve result acquisition. The injected fluid was carbonated water made from synthetic sea water (salinity of 38 kppm) saturated with 21.5% of total solubility in CO2 X-ray Computed Tomography (CT) provided image acquisition allowing the evaluation of porosity evolution throughout the tests.

Experiments showed a tendency for porosity increase for the sample in the first coreholder, possibly associated with rock dissolution. The spatial porosity profile from the CT scan for the first coreholder showed porosity variation in the first centimeters of the rock sample inlet. In the second coreholder, porosity remained unchanged during the entire test, indicating that the dissolution effect promoted by carbonated water injection was most notable in the first sample when compared with the second.

The amount of dissolved moles afforded the behavior regarding dissolution phenomena. Permeability behavior was analyzed through the pressure drop values from the sample for the entire experiment, registered by pressure transducers installed in each coreholder. Results showed consistent permeability behavior for the first coreholder samples, despite the tendency of the porosity to increase. The samples placed in the second coreholder presented lower permeability because minerals dissolved in the first sample were transported to the second sample and likely precipitated and so related to the porous media blockage.
Reduce the Costs of Ignorance through Retention of Critical Knowledge
Authors: Spek Rob van , Kelleher Michael
Published: November 2017

Common sense says that learning from experiences, both successes and failures and the ability to re-use lessons identified will lead to the continuous improvement of performance (Swieringa 1992, van der Spek & Kingma 1999, Weick 2011). An organisation's effectiveness and resilience can be leveraged by organizing three core learning processes in a smart and sustainable way: Learning from successes and failures, on individual, team or company level;Learning from each other, both from co-located colleagues as well as colleagues that might be located at a further distance through geography, organizational structure or discipline;Learning from ‘outside-in’, from partners, suppliers, customers and even competitors.

However, in many companies, these learning processes might not function properly anymore and need attention and support. This may be caused by many reasons, such as: Competing rather than collaborating divisions;Differences in culture, pressure of the daily challenges;Lack of communication tools and places to meet;Poor discipline;Counter-productive incentives within the company;Overload of data and information in disconnected silos.

These barriers create various symptoms (van der Spek & Spijkervet 1997): Non-productive time of assets due to unexpected failures or sub-optimal operations;Duplication of mistakes because earlier ones were not recorded or analysed;Re-invention of the wheel because people are not aware of activities, projects in the past or their outcomes;Good ideas and best practices are not shared which raises overall costs;Loss of critical knowledge due to retirement and mobility of work force;1 or 2 key employees hold crucial knowledge creating continuity risks;Slow innovation which results in delayed product development or missed opportunities;Frustrated employees because it takes too long to find validated content or the right experts.
Revitalized Three-Dimensional Design Method Improves Tubular Design
Authors: Aasen Jan A. , Ostvold Tor D. , Aadnoy Bernt S.
Published: November 2017

The ANSI/API Technical Report 5C3 was updated with addendum Annex M in October 2015 (informative). This is a significant step forward, since the effect of internal pressure on collapse is now calculated on the basis of Lubinski (1975) theory instead of using an inaccurate approximation. This theory is utilized in the present study to demonstrate three-dimensional model with API design formulas expressed as a circle instead of the conventional ellipse. The presented three-dimensional method is easy to use and the main user group is drilling and well engineers working in the field or in well tubular design.

Industry practice is to use the effective axial tension (buoyed force) for buckling calculations, while for yielding and collapse analysis the actual axial force is used. In this study we use the effective tension for yielding and collapse calculations, thus employing a stress reference datum that is in agreement with buckling equilibrium and buoyancy. Using the effective tension, a yield circle is produced instead of the conventional yield ellipse. The circle is easy to use and a full set of design equations including buckling stresses are developed in this study.

Effective force is equivalent to oilfield definitions such as fictitious force, buckling force, stability force and buoyed force. Note that for some of these terms compression is defined positive. A comprehensive set of equations for yielding and collapse are presented in this study, where the theory includes bending stresses from helical buckling and wellbore curvature. Tension is defined positive herein while compression is negative.
First Successful Single-Trip Hole-Enlargement-While-Drilling and Rathole Elimination Operation in Indonesia Using Integrated Borehole Assembly Design and Modeling
Authors: Noviasta Bonar , Awaliyah Siti , Sonny Shannon , Pratama Kevin , Hasibuan Frengky
Published: November 2017

Well A, drilled by KN, an oil & gas operator in Indonesia, is a deepwater vertical exploration well located offshore Bali. The high cost of a deepwater operation demanded all drilling components to be as efficient as possible. One of the optimizations performed was a single-trip hole-enlargement-while-drilling (HEWD) and rathole elimination (RHE) operation, in which drilling the pilot hole, opening the hole, and eliminating the rathole were all executed in one run.

The key component of the single-trip HEWD and RHE was the on-demand hydraulically actuated reamer, an underreamer with advanced technology by which activation based on flow index is used instead of a conventional ball-drop system; this enables the tool to be positioned below measurement- and logging-while-drilling (MLWD) tools, closer to the bit. This advanced technology, however, required extensive preplanning activities, especially for bottomhole assembly (BHA) vibration and hydraulics modeling. Multiple BHA alternatives were evaluated using simulation based on finite element analysis (FEA) in terms of stability, and the most stable BHA was selected. In regard to hydraulics, sufficient pressure drop below the reamer and rotary steerable system (RSS) tool needed to be achieved to ensure the full cutter-block opening capability, as well as the RSS functionality.

The integrated BHA design and modeling successfully delivered an excellent single-trip HEWD and RHE operation in two different hole sections. The 12 1/4-in × 14 1/2-in BHA used an RSS to drill a 1,400-ft interval in HEWD mode and eliminated 157 ft of rathole using the on-demand reamer. The 10 5/8-in × 12 1/4-in BHA drilled 1,418 ft with HEWD and eliminated 182 ft of rathole. A savings of 57 operating hours (equal to USD 1,425,000) was realized as a result of eliminating a dedicated RHE run. The 11 3/4-in liner and 9 5/8-in casing were smoothly run to bottom, indicating a good hole quality produced by a stable HEWD and RHE system.
Case Study - Failure Caused by Mercury Embrittlement in MCHE Main Cryogenic Heat Exchanger in a LNG Plant
Authors: Zeeshan Anwar , Manikandan A.
Published: November 2017

This is a case study explaining the failure of an inlet nozzle to a Main Cryogenic Heat Exchanger (MCHE) used in a LNG plant, causing the refrigeration compressors to be in shutdown for 6 weeks. This resulted in loss of LNG production. The failure analysis of the nozzle indicated the cause of failure was Mercury embrittlement that is made of Aluminum, which caused flange leakage.

Main Cryogenic Heat Exchanger (MCHE) is made of aluminum and part of refrigeration process in a LNG plant MR (mixed refrigerant) loop. The Mercury embrittlement is a form of liquid metal embrittlement (LME) and a complex metal fracture mechanism that occurs without any warning indications. Mercury embrittlement, being a significant problem in LNG Plants using aluminum MCHE, have led to number of major plant incidents worldwide. Mercury is always present in natural gas feed stocks, sometimes in quantities sufficient to cause severe attack and failure of Aluminum heat exchanger.

To avoid Mercury embrittlement failure in aluminum heat exchanger tight limits have been placed on allowable mercury levels in natural gas passing through Aluminum heat exchanger. The natural gas is pretreated with mercury removal units before entering the refrigeration units in a typical LNG plant. Root cause of this failure is identified as the failure of mercury removal units to remove the mercury efficiently. In this case study,

Different type of mechanisms has been highlighted by which the mercury degrades the aluminum heat exchanger that includes LME, Amalgamation and Amalgam Corrosion. The importance of mercury removal units in LNG plants is emphasized. Different types of mercury removal technology are explored and discussed.

This case study Introduce the newly developed high activity mercury removal absorbents that allows greater flexibility in the design of LNG plants. These absorbents allow for smaller beds, which coupled with new reactor designs improve savings in compression costs. It is now possible to locate the mercury removal units upstream of the main gas processing plant and thus avoid mercury emissions and contamination of any co-produced Natural Gas Liquids (NGL) in a LNG plant.
ADMA Rigless Intervention Campaign: Breathing New Life in to Old Wells
Authors: McNeilly K. , El-Sayed M. A. , Al-Blooshi J. , Al-Qubaisi S.
Published: November 2017

The ADMA Rigless Intervention "Cheap Oil" Campaign is an on-going initiative begun in 2015 to drive ADMA-OPCO to execute cost effective rigless wellwork interventions to maximize recovery, extend the economic life of the super-giant offshore field, and breathe new life in old wells. The scope of the project included an extensive well review to identify rigless opportunities, creation of a Wellwork Hopper to rank ideas based on economics, design and support of intervention execution, and development of Wellwork Tracking System to measure post-job value.

During this campaign, a novel rigless intervention technique was generated and applied to four inactive wells in ADMA resulting in the successfully reactivation of 6,000 bopd total from the wells. The technique utilizes methods and equipment never used in ADMA before. When combined together, these new methods and equipment have the potential to unlock significant value within the ADMA Inactive String well stock.

As of Jul-2017, the total campaign has successfully completed 70+ interventions adding 30+ mbod oil instantaneous gain and 40+ mbwd water injection instantaneous gain using new wellwork techniques and technologies.
Large WAZ Broadband Seismic Data: From Acquisition to Evaluation
Authors: Al-Abri S. S. , Riyami J. , Kiyumi R. , Haupt E. , Shaibani M.
Published: November 2017

In 2012, the PDO Geophysical Operations team started to acquire the largest 3D seismic survey to be acquired in Oman, with a total area of 8000km2. Here we will present geophysical workflow for that survey, including 3,000 km2 of the Umm As Samim sabkha. Before the acquisition of this survey, the area had limited 3D seismic coverage due to its highly complex and logistically difficult environment. To ensure the survey would be acquired safely; extensive scouting was put in place, bulldozers were used to construct graded tracks across the buckled sabkha crust outside which the workforce was not allowed to walk. Furthermore there was a continuous measurement of the water level below the sabkha and there were contingency plans in place in case the sabkha got flooded.

The 8000km2 area was split into 4 blocks overlapping with an acquisition geometry of 25x250m receiver grid and 25x100m shot grid. The acquisition recorded up to 30km inline offset and 6km cross-line offset and sweeping from 1.5 to 86 Hz. To expedite the seismic for interpretation, the processing started a couple of weeks after the first shot, and it was done in 4 phases. The first phase consisted of signal processing and pre-stack time migration of the first two blocks. This was followed up by pre-stack depth migration of the first two blocks in the second phase. In phase 3, the phase 1 processing was reperated for blocks 3 and 4 and finally in phase 4 all blocks were merged and depth migrated to give seamless volume. The processing of the data was executed in phases to speed up the evaluation of the data for exploration purposes. The integrated team has allowed an optimum processing of the data. The survey took 29 months to acquire with a detailed pre acquisition planning to mitigate potential HSSE risks in the area such as Umm As Samim sabkha and hydrocarbon field facilities. In order to minimize the acquisition gaps in the wet sabkha, light vibrators were used. Due to the massive size of the survey, data quality over the area was different and this led to a change in the workflow from one block to the other. This has lead to re-work to ensure a seamless merge could be accomplished over the whole area. Superior data quality compared to legacy data led to a number of wells being planned or changed position due to the improved imaging. Phase three and four led to an increased confidence on evaluation of prospects (both volumetric and risking) and reducing HSSE risk. As part of the deliverables, acoustic impedance volumes have been generated; these volumes will help the interpreters to more accurately pick events as well as having a first view on the reservoir quality of identified prospects. This project is a result of close cooperation and synergy in delivery between Exploration and Production.
Combined Viscoelastic Surfactant and Induced Imbibition for CEOR of Low Permeability Reservoir
Authors: Hongyan Cai , Yi Zhang , Jianguo Li , Maozhang Tian , Wenli Luo
Published: November 2017

Presently, water flooding low permeability reservoirs face severe development challenges, such as early water breakthrough, low productivity, and low recovery. In view of this, a CEOR method combined by warmlike micelle and surfactant imbibition was recommended and detailed in-lab evaluations were performed.

Warmlike micelle (WLM) made from viscoelastic surfactant (VES) has special rheological characteristics, showing great potential for swept volume increasing through viscosifying effect in low permeability reservoirs. Some surfactants can induce spontaneous imbibition through capillary force effect, wettability alteration, and oil film removal to enhance recovery. Herein, warmlike micelle and surfactant imbibition were combined to both increase swept volume and induce spontaneous imbibition.

Rheological properties, imbibition recovery, and core flooding performance were evaluated for a reservoir with average permeability of 3.51 ×10-3μm2. At shear rate of 7.34 s-1, the viscosity of 0.30% VES solution amounted to 25.4 mPa.s at 70 °C. Static imbibition test by outcrop showed imbibition recovery of 68.7% was achieved by surfactant AEC. After that, three runs of core flooding tests were conducted to evaluate the performance of prepared formulations. For VES only formulation, an incremental recovery of 8.50% was obtained after water flooding with recovery of 32.81%. For the combined VES and surfactant imbibition formulation, 14.82% incremental recovery was achieved. Synergistic effect of VES and spontaneous imbibition motivated more remaining oil because of dual effects.

The developed CEOR method takes advantages of VES and imbibition, demonstrating promising potential for further development of low permeability reservoir.
Development of Comprehensive Inspection Program for Drill Bits Through Joint Industry Project for Failure Risk Mitigation and Reduction of Inspection Costs
Authors: Mulunjkar A. M. , Durairajan B. , Williams J. , Griffo A. , Gokhale S. R. , Wells A.
Published: November 2017

There is an absence of industry-wide, globally accepted standards that provide comprehensive inspection procedures and acceptance criteria for inspection and maintenance of drilling bits, including: wear, cracking, and mechanical damage criteria for bit bodies and cutting elements. Nevertheless, bits are routinely inspected and evaluated to determine their usability for both land and offshore drilling operations. This creates significant risk for all drilling operators because the lack of clear inspection criteria can lead to the use of bits with flaws causing downhole failures. In addition, the lack of an industrywide bit inspection specification has challenged bit suppliers since the decision to use a bit with indications and damage can be subjective and the potential risk severity can be high.

Industry standards like API, ISO and DS-1 for inspection of other drill stem components do exist. However, the application of these standards to bits, particularly those with matrix bodies, is inappropriate. Using acceptance criteria adopted from existing standards for other drill stem components creates significant risk by accepting minor damage and rejecting major damage without an industry accepted standard. To overcome these limitations, a technical committee consisting of operators, drilling contractors, service providers, manufacturers, and inspection companies, worked together to develop specific procedures and acceptance criteria for the inspection of bit bodies as well as cutting elements.

This paper presents the procedures and acceptance criteria developed by the technical committee that address the inspection of cracks and porosity in matrix and steel bit bodies, wear and erosion of bit bodies, cracks in PDC cutters, and other damage to cutters. The information included in this paper was considered for development of the DS-1 Bit Inspection Technical Standard (BITS) to address the necessity of a globally accepted standard for the inspection of bits.
Integrated Fracturing Services Project: A Success Story of Collaboration Between Operator and Service Company
Authors: Sayapov E. , Nunez A. J. , Al Gheilani H. , Ibrahim E. G. , Al Ghaithi A. , Al Salmi M. , Al Farei I. , Kelkar S. K. , Kurniadi S. D. , Al Zeidi O. , Barakat A. M. , Al Kalbani M. S.
Published: November 2017

An integrated fracturing services (IFS) project between Petroleum Development Oman (PDO) and Schlumberger started in November 2009 and spanned a 7-year period until November 2016. It steered the local fracturing industry from standalone operations to an integrated package, offering collaborative services between hydraulic fracturing, coiled tubing, and well testing services. The synergies between the various services allowed for a more streamlined decision-making process between the operator and the service company. Ultimately, this led to faster well delivery times, lower non-productive time, and maximum utilization of personnel.

The integrated approach was primarily based on communal resource pooling which was available for any of the services on location at any given time. At its prime, the IFS project comprised of 4 fleets deploying almost 300 employees across the Sultanate of Oman's northern and southern fields. The coordination process was centralized and handled by a dedicated team in charge of logistics, transportation, personnel, and resources. This centralization process was essential for the IFS workflow, and it was primarily managed by the service company in collaboration with the operator's well engineering team.

Tangible results were achieved, and the IFS model added a new dimension to the fracturing industry in the Sultanate. It allowed the operator to align its well development operations with its production goals and delivery times. It also provided the service company with an opportunity to bridge operational and communication gaps, which would have been harder to achieve if other vendors were involved. These high-level results were coupled with operational successes by the fracturing, coiled tubing, and well testing crews.

The novelty of this project is in the dynamism of all available communication channels, as well as the elimination of operational lag due to the reduced number of vendors in any given location. The success of the IFS program makes it PDO's first-choice fracturing model, especially during the current downturn when lowering operational costs is of utmost importance.
Carbonate Clinoforms, Sinkholes, Reefs, and Flow Units: Integrated Seismic Reservoir Characterization in Shuaiba Formation UAE
Authors: Strecker Uwe , Ibrahim Mahmoud Mudi
Published: November 2017

Integrated seismic reservoir characterization of carbonate rocks potentially thwarts difficulties arising from reservoir heterogeneity owed to a complex geological history. The featured interdisciplinary workflow reconciles geological, geophysical and engineering components to address reservoir complexity in terms of stratigraphic architecture coupled with a distribution of layer properties that honors flow zonation. Primarily, this workflow calls for a combination of hydraulic flow unit definition embedded in sequence stratigraphy and is further augmented by seismic attribute analysis (i.e., seismic inversion, frequency decomposition of amplitude, etc.), rock physics, and geostatistical techniques to characterize an UAE onshore oil reservoir located within a Lower Cretaceous carbonate sequence (i.e., lower member of Shu'aiba Formation; Strohmenger et al., 2010). Our results to-date encourage us to further characterize the reservoir applying geostatistical techniques (seismic stochastic inversion, fuzzy math) in a future companion paper.
Integrated Characterization of the Regional Aquifers in Abu Dhabi Onshore. Dammam, Umm Er Radhuma and Simsima Formations. UAE
Authors: Parra Humberto , Ghosh Dipankar , Tahir Sofiane
Published: November 2017

Regional aquifers are critical for development of oil/gas fields that need water injection for pressure maintenance. However, modeling of regional aquifer is a difficult task as data acquisition and analyses are primarily focused on hydrocarbon bearing intervals. Also, aquifers are generally regional, whereas the data available is clustered around oil/gas fields with negligible data in the vast areas lying outside the fields of interest. The present study aims at building a regional aquifer model for Abu Dhabi Onshore area integrating all the available data in different scales that may be used in planning future availability of water resources.

Most of the oil/gas fields located in Onshore of Abu Dhabi have so far been developed by primary pressure maintenance strategy injecting water obtained from the shallower Late Cretaceous, Paleocene and Eocene aquifers. The main water source reservoirs are Dammam, Umm Er Radhuma and Simsima formations. Despite limited data availability, the study delivered a fit for purpose 3D reservoir model integrating seismic data, regional outcrop analogs and available log and core data. An enormous database containing 4768 wells from 10 most important Fields of onshore Abu Dhabi was used to build the structural framework with the help of regional seismic interpreted surface. Sequence stratigraphic cycles were identified in all the formations considering eustatic curves and correlation using GR-NPHI-RHOB logs. Average layer thickness was designed to be around 20ft in all the reservoir intervals. Input for property model was very limited as logs and cores are generally not acquired in aquifer intervals. Wells with NPHI-RHOB logs were used for estimation of porosity and it was calibrated with limited core porosity data available. Permeability has been computed by fitting functions to Poro-Perm cross-plot and then adding statistical dispersion based on observed core permeability data. Different scenarios of permeability were defined due to the high dispersion in the core data. For dynamic modelling three equilibration regions were setup for the main three aquifers and a common PVT table was used. All the water supply and disposal wells were used in history matching. The high case of permeability was found to honor best the production and injection data.

The static model built integrating all available data in different scales is robust. Although limited data availability for property modelling was a major concern, the model did show reasonable history match and is fit for purpose to predict future water supply. A systematic data acquisition plan for these aquifers may be implemented in future to make the current model more reliable.

The regional aquifer model of Abu Dhabi Onshore is the first of its kind in the country that incorporates all the available information including seismic interpretation in regional scale to small-scale core data.
Surface Complexation and Equilibrium Modelling for Low Salinity Waterflooding in Sandstone Reservoirs
Authors: Elakneswaran Y. , Shimokawara M. , Nawa T. , Takahashi S.
Published: November 2017

Changes at oil/brine and sandstone/brine interfaces can improve oil recovery in sandstone reservoirs by low salinity waterflooding (LSWF). There have been several attempts to understand the interfaces through both experiments and modelling, but the results are inconsistent and the existing models did not consider the important mechanisms on prediction. In this study, an integrated model incorporating surface complexation reaction, dissolution/precipitation of minerals, and speciation was developed to simulate LSWF in sandstone reservoirs. A separate surface complexation model was developed for oil-brine and kaolinite-brine interfaces. The effect of pH and divalent ions of calcium and magnesium concentration on surface species of oil and kaolinite is analyzed. These surface complexation models were combined and coupled with phase-equilibrium model to predict LSWF in sandstone reservoir. Deprotonation of Al and Si sites (>Al: SiO−) of kaolinite and both deprotonated carboxylic groups (−COO−) and calcium-adsorbed (−COOCa+) dominates the surfaces at various brines and its diluted composition. The pH rise in the formation water increases the dissociation of both oil and kaolinite and hence high repulsion between the surface. The desorption of oil was calculated from the surface species concentration of both oil and kaolinite. The simulation results on desorption of oil increases with dilution times (up to 20 times) and amount of equilibrated brine of seawater, formation water, 20 mmol/l CaCl2, and 20 mmol/l MgCl2. Consideration of phase-equilibrium significantly impact on the simulation results; the dissolution and precipitation of sandstone minerals increase the desorption of oil by few percentages, 6-10% in seawater flooding. Increased oil recovery in LSWF is strongly depend on the aqueous chemistry of injected solution and surface electrical properties, such as surface site density and equilibrium constants for ionization and ionic adsorption of oil and kaolinite. The simulation results of this study emphasize the importance of surface chemistry of oil and kaolinite as well as phase equilibrium reactions on improved oil recovery in LSWF. The key factors affecting electrostatics of oil and kaolinite and then oil recovery was identified and analyzed. The potential improvement of the model for better prediction is discussed. The proposed model could serve as a useful tool to predict oil recovery during LSWF in sandstone reservoirs.
World Drilling Limit Envelope: Why it Shows an Irregular Triangle?
Authors: Li Xin , Gao Deli , Jiang Zhenxin , Li He , Zhang Hui
Published: November 2017

Many scholars have carried on the related researches of world drilling limit envelope and provided the TVD (true vertical depth)-HD (horizontal displacement) charts. Those charts show that both the ultra-deep well and the extended-reach well (ERW) with extremely high HD-TVD ratio are relatively rare, while those wells have a certain TVD as well as a certain HD formed the majority part of these charts. Why the envelope shows an irregular triangle as a whole? There exist theoretical reasons except for the reasons of economic benefits and drilling needs. This paper mainly analyze the following four kinds of well: 1) the ultra-deep well; 2) the vertical well and the directional well with identical TVD; 3) the horizontal ERW; 4) two ERWs with identical measured depth (MD). These analyses can be used to explain why the world drilling limit envelope shows an irregular triangle. The research shows that drilling limits are restricted by borehole space, well deviation, bearing capacity of drilled formation, mechanical factors and hydraulic factors simultaneously. These factors working together make the world drilling limit envelope as an irregular triangle. The factors that limit the well’s MD can be divided into two categories: subjective factors and objective factors. The subjective factors can be broken by upgrading the drilling equipment and improving the drilling technology. However, the bearing capacity of drilled formation is an objective factor which cannot be changed. It is the ultimate factor that restrict the drilling limit. In addition, some optimization control measures are proposed, which are beneficial to break the world drilling envelope.
Building the Next Generation of Petrotechnical Professionals through Gamification
Authors: Ugoji Paul , Ibhadode Akii , Amadi Anslem
Published: November 2017

There is a gradual awareness which indicates some level of shortage in the generation of technically skilled manpower for the petroleum sector and other industries. With an increasingly ageing experienced work force, funding constraints for training, increased employee turnover, reduced field exposure, reduced interest from graduates etc, there is need to reassess the mode of teaching and man power training for the petroleum sector in our various institutions considering the fact that the education sector stands as the main source of personnel generation for the sector.

This paper tries to highlight the skills and employability needs of employers from different sectors with special focus on the petroleum sector. With these needs as a guide, an appropriate gamification strategy that would provide the required outputs for employers is being implemented with emphasis on key gaming components missing in our educational system. That way, graduates from tertiary institutions would be fully equipped for work immediately after graduation since they would have been exposed in a fun-filled way to issues that are important to employers of labour. This plan would also enable higher institutions to highlight areas of study and interests that they lack. The government and private sector, especially the oil and gas sector, can then play a positive role in enhancing their academic curriculum.

A pilot program was undertaken in 2016/17 with the gamification of multiple facilities that have links to the petroleum industry. This was setup at the Federal University of Petroleum Resources, Effurun, Delta State, Nigeria and the feedback from the participants has been included in this paper. The program would be made to gradually evolve over time in the hope that its coverage would be enhanced such that employers would find it easy to spot and acquire outstanding student talents with the specific qualities they need directly from various institutions even before graduation. This way, general training costs required by companies in the petroleum sector would be reduced since various institutions would have covered most of their key needs due to the infusion of critical skills developmental elements into the gamification process.
ERD Wells on Remote Artificial Islands: Successful Optimization Strategy to Boost a Performance
Authors: Ruzhnikov Alexey , Banda Maria Yanez , Malagon Cecilia , Al-Wahedi Khalid , Toki Takahiro , Benygzer Mhammed , Singh Rudra , Alzate Jose , Kasem Youssef
Published: November 2017

From the start of the drilling campaign on the remote Satah Al Razboot (SARB) artificial islands located in United Arab Emirated (UAE) the operator used multiple optimization initiatives to enhance drilling performance and well delivery.

Even though the complexity of the wells increased over time, when extended reach drilling (ERD) envelop started to expand, with the implementation of optimization initiatives the well construction time significantly decreased. This paper describes the way of thinking and steps taken to boost the performance to the absolutely new level for the operator.

The main objective in actual harsh economic conditions was to drill the wells under the budget without jeopardizing well integrity, service quality and HSE. The ultimate goal was to decrease well construction time by 25%. To achieve this goal, several well construction optimization workshops were organized aiming to challenge and find improved drilling processes, operations procedures, tools, equipment and well design, as well as to have a clear plan on smooth expanding ERD envelop.

In addition with the workshop initiatives, an Operational Performance Improvement Plan was developed aiming to analyzed all operational opportunities to reduce time; a dedicated well engineering, subsurface and operations team was set up to lead the feasibility studies and ensure the implementation of the approved initiatives.

Implementation of all performance improvement initiatives required a balance between all involved parties. Every decision should be verified by multiple teams, included but not limited by drilling, equipment, completion, subsurface, production and intervention. Once the approval is obtained then the initiative is implemented and analyzed, taking into account increasing complexity of the wells and lesson learnt captured. At the same time not all the initiatives were implemented – some were rejected due to significant increase of service quality risk; some due to HSE associated risks. The implementation of the initiates and ideas contributed to the reduction of flat time, elimination of online operations, etc.

The manuscript describes the steps taken to drill extended wells within shorter time compare to standard deviate and horizontal wells. It highlights main challenges faced during implementation of the performance improvement plan and describes techniques and technologies used to overcome them.