bluuebunny/crossref_metadata_2025 huggingface dataset:
Finding the Optimal Horizontal Well Trajectory using Monte Carlo Techniques: Implementation Details and Case Study in Abu Dhabi, UAE
Authors: Arroyo Negrete Elkin , Webb Steve , Rodriguez Jose , Mavromatidis Angelos , Al Blooshi Ahmed , Basioni Mahmoud
Published: November 2018

Optimal field development plans are often required to maximize reservoir recovery while keeping costs low. This paper discuss the details of how to select the optimal horizontal well trajectory that maximizes reservoir recovery for an interbedded thinly layered carbonate reservoir. The case study here was applied to one of the largest wet gas / gas condensate fields in the UAE. The development plan targets four different reservoirs using horizontal wells. Each reservoir has different rock qualities, and the top reservoir is not in communication with the three reservoirs below.

Each reservoir contains 3-4 sub-layers with varying reservoir properties. Some of the sub-layers may not be in communication with the others, and the vertical communication could be poor. In order to maximize recovery, the development plan calls for placing the horizontal wells crossing from one sub-layer to another sub-layer. The problem is in deciding how long the horizontal well should stay in each sub-layer. Since there are four reservoirs and an average of three sub-layers per reservoir, there are twelve possible lateral placement options that control the well trajectory and length. The methodology presented in this paper utilizes Monte Carlo sampling to calculate the well trajectory that maximizes recovery. The methodology resembles the ideas of the Metropolis Algorithm used in the Marko Chain Monte Carlo. The starting point uses an arbitrary well trajectory. This well trajectory is run in the simulator, and the cumulative production is saved as a reference. Subsequently, the same distribution is sampled and the simulator is run again. If the resulting recovery is greater than the initial recovery or the recovery from any prior iteration step, then the newly found well trajectory is used as the new mean of the distribution, and the steps are repeated until simulated field recovery does not substantially increase.
Novel Application of Coriolis Meters in Custody Transfer Applications
Authors: Rajendran Arivazhagan
Published: November 2018

This paper describes the novel application of Coriolis Meters in custody transfer applications related to ADNOC Gas Processing sales gas network. Though Ultrasonic meters are the preferred choice for custody transfer applications, Coriolis meters are widely used for similar applications in smaller pipelines due to its accuracy and turndown ratio as well as less Operational Expenditures.

Coriolis flow meters operate based on the Coriolis principle invented by Gaspard Gustave de Coriolis over 180 years ago. The Coriolis meter directly measures mass flow. It consists of a tube that oscillates at its resonance frequency. If the tube is empty, it will oscillate uniformly but if it is not empty, twisting of the tube will be observed resulting in phase shift between the two ends of the tube which is directly proportional to the flow. Also, this technology can be utilized to simultaneously measure the density as the oscillation is inversely proportional to the density.

Even though turbine and positive displacement meters are suitable for custody transfer applications, Coriolis flow meters are preferred as they do not have moving parts. Coriolis meters provide increased accuracy because of its ability to directly measure mass flow without the requirement for temperature and pressure compensation. It is not affected by the flow profile, thus does not require upstream and downstream straight length requirements. In addition, it is reliable, fast and has diagnostic features as well as dynamic responses which make it fully suitable for custody transfer metering.

Although the associated Capital Expenditures are high, for lower line sizes (6" size and less), their Operational Expenditures are relatively low, resulting in lower total cost of ownership.

Coriolis flow meters are conventionally used for liquid applications. For gas custody transfer applications, ultrasonic meters are predominantly recommended for larger pipe line sizes. However, for lower line sizes (6" size and less), ADNOC Gas Processing follows AGA (Report No. 11: Measurement of Gas by Coriolis Meter, approved by API for Custody Transfer Applications of Gas) standard to implement the technology in custody transfer metering applications for sales gas, and it has been found to be successful.
From Sand Production to Oil Recovery Through the Unusual 3 ¾-in. TTRD Application on Gullfaks Field, North-Sea
Authors: Khalil Haitham , Labrousse Sebastien , Caycedo Alberto , Moldekleiv Rune , Downie Simon , Esmat Mohamed , Færevåg Vidar , Kristian Andersen Stein
Published: November 2018

Drilling a re-entry well is a routine operation on mature fields. Several techniques are generally used for re-entry operations including cement plug sidetrack and whipstock sidetrack (Hussain et al. 2016). Often the completion string is pulled prior to performing the sidetrack operation but when it is not, one calls this operation a Through Tubing Rotary Drilling (TTRD). Benefits of TTRD wells include lower cost to access small hydrocarbon reserves.

Through-tubing wells are usually drilled with small hole sizes and in Norway such wells are generally drilled with 5 7/8-in. or 5 ¾-in. hole sizes. In this paper we present the case of a through-tubing well drilled with an uncommon 3 ¾-in. hole size.

This paper will: Present the reason for planning such a sidetrack: drilling 3 ¾-in. hole is a rare operation on the Norwegian Continental Shelf (NCS)Describe the solution selected for the operation, including the directional plan, the whipstock setting operation and the 3 ¾-in. bottom hole assemblySummarize the risks and compensating measures associated with this solution, including the low buckling margins in this well planned at inclinations higher than 90°, the low tolerances on the downhole connections that could lead to a twist-off, the limited experience with the directional behaviour of such a slim bottom hole assembly, the bit design.Present the results of the successful operation: this rare 3 ¾-in. hole drilled on the Norwegian Continental Shelf was drilled successfully and below budget.Find the main drivers that will make this solution portable to other situations

This case study demonstrates how detailed and thorough planning based on modelling led to the successful delivery of a rare well design at first attempt. It is an objective of this paper to share some key elements that will be useful for the planning of similar operations in other wells in the future.
Technology Demonstration Journey in ADNOC R&D – A Case Study
Authors: Khan Ibrahim M , Al Wahedi Yasser , Balasubramanian Vaithilingam , Tsapatsis Michael , Geuzobroek Frank , Saif Al Nasr Adel , Al Daghar Khadija
Published: November 2018

This paper explains the process work flow steps starting from the proof of concept of a new research technology up to the field demonstration considering a live example. We discuss the stages that are employed in ADNOC R&TD technology management process in assessing proposals, supervising projects progress, steering projects towards technology maturity. The example under study pertains to a research project which was awarded to Khalifa University (KU). The project attempts at solving high SO2 emissions from old Sulfur Recovery Units (SRUs) in ADNOC Gas Processing. The subject project is research work involving development of a mixed metal oxide, highly selective regenerable adsorbent possessing high adsorption capacity of 6 to 8 mmol/g. We follow the progress of the new technology via the various steps of ADNOC R&D technology management process.
Insight on the Exploration Potential of the Ordovician Gas Play in Tunisia Ghadames Basin, North Africa
Authors: Troudi Habib , Chevalier Francis , Alouani Wael , Mzoughi Wala , Abdelkader Omri
Published: November 2018

In Tunisian Ghadames sag basin, a significant portion of natural gas resources are looked within low permeability Ordovician sandstones deposited immediately below the Early Silurian Tannezuft world-class source rock.

The objective of this study was to develop an integrated approach to better estimate the amount of gas stored in this emerging play via the analysis of four fundamental elements: 1) the thermal maturity of the Silurian ‘hot shales’ source rock, 2) the trapping mechanism and the architecture of Upper Ordovician paleo-valleys, 3) the impact of diagenesis-lithofacies association on petrophysical properties, and 4) the fracture distribution/density and their contribution in the production.

The Early Silurian hot shales constitute the essential ingredient for the development of a pervasive gas accumulation play. The gas generated at the deeper part of the basin has charged the underlying Ordovician low-permeability sandstones mainly through complex faults system inherited from the basement. During hydrocarbon maturation and charging, pore pressure increases at rates that exceed the normal gradients, leading to local over-pressure as seen in several wells drilled down to the Ordovician reservoirs. Lateral migration via regional faults is confirmed by numerous discoveries at the edges of the basin far away from the gas kitchen.

Besides the structural closures accumulations, more complex structural/stratigraphic or purely stratigraphic traps are deemed within the Late Ordovician, and documented for instance by the development of incised paleovalleys filled with multiple fluvio-glacial and marine clastic sediments (i.e Algeria, Libya). The discovery of hydrocarbon pay zones outside of structural closures and the result of the long term tests confirm this hypothesis.

Based on seismic data it is generally very hard to recognize the paleorelief marking the base of the Late Ordovician sequence. Key elements from core studies, regional correlations, isochore maps and sequence stratigraphy have been combined accordingly, leading to a conceptual model within the observed framework. It is then possible to identify the multiple incision surfaces associated with reservoirs of Jeffara and M'Krata Formations.

The reservoir quality is considered as a major risk in deep areas (>4 km). Although, the primary pores space have been occluded by quartz overgrowths and clay cementation or lost by lithostatic compaction. The substantial gas rates observed in several wells drilled in the junction of NE-SW and NS fault trends constitute an evidence of the contribution of open fracture into the flow.

This new insight into this play has been used by OMV to identify in Ghadames basin the area with possible "Tunnel Valley features", analogues to those drilled in Libya Murzuk basin (Ghienne, 2003).
Hydrocarbon Accumulation Model of Upper Cretaceous Mishrif Formation and Oilfield Discovery in Western Abu Dhabi
Authors: Lv Mingsheng , Al Suwaidi Saeed K. , Ji Yingzhang , Swain Ashis Shashanka , Al Shehhi Maryam , Luo Beiwei , Mao Demin , Jia Minqiang , Zi Douhong , Zhu Jin , Ji Yu
Published: November 2018

Western Abu Dhabi locates in the west of Rub Al Khali Basin, which is an intra-shelf basin during the Late Cretaceous. The Shilaif source, Mishrif reservoir and Tuwayil seal forms one of the Upper Cretaceous important petroleum systems in the western Abu Dhabi Onshore. However, less commercial discoveries have been achieved within Mishrif Formation during the past 60 years since the large scale structures were not developed in western Abu Dhabi and the stratigraphic traps have not been attracted attention.

This study aims to investigate the exploration potential of both Mishrif structural and stratigraphic traps. It provided detailed study on Shilaif source rock, Mishrif shoal/reef reservoir and Tuwayil seal capability. Oil-source rock correlation, reservoir predication and basin modeling have been carried out for building Mishrif hydrocarbon accumulation model by integration of samplings, wire loggings and 2D&3D seismic data. Shilaif Formation is composed of laminated, organic-rich, bioclastic and argillaceous lime-mudstones and its generated hydrocarbon migrated trending to high structures. Three progradational reefs/shoals in Mishrif Formation were deposited along the platform margin, which are characterized by high porosity and permeability. Tuwayil Formation consists of 10-15ft shale interbedding with tight sandstone, acting as the cap rock of Mishrif reservoirs.

Mishrif hydrocarbon accumulation mechanism has been summarized as a model of structural background controls on hydrocarbon migration trend and shoal/reef controls on hydrocarbon accumulation. It is consequently concluded that Mishrif reefs/shoals overlapping with structural background are the favorable exploration prospects, and oil charging is controlled by heterogeneity inside a reef/shoal, the higher porosity and permeability, the higher oil saturation. Two wells have been proposed based on the hydrocarbon accumulation model, and discovered a stratigraphic reservoir with high testing production. This discovery encourages a new idea for stratigraphic traps exploration, as well as implicates the great exploration potential in western Abu Dhabi.
Pushing the Limits of Coiled Tubing to Address the Challenges of Matrix Stimulation in Multi-Lateral Extended Reach Power Water Injector
Authors: Jassem Hasan , Salman Naji K. , Said Rifat , Ahmed Danish , Al Hamwi Kaisar
Published: November 2018

In Middle East carbonate reservoirs, power water injector (PWI) wells are typically completed with long openhole laterals. The reservoir contact provides pressure support and enhances sweep efficiency in the low-transmissibility reservoirs. Due to the wells deviation and length, coiled tubing (CT) interventions are required to successfully enter and identify each lateral, as well as to remove formation damage by pumping the matrix stimulation treatment across entire laterals.

During such CT interventions, laterals are accessed thanks to a hydraulically operated lateral identification tool (LIT), while the stimulation treatment is pumped through a ball-drop-activated high-pressure jetting nozzle (HPJN). LIT and HPJN are efficiently operated by monitoring downhole pressure values both inside and outside of the bottomhole assembly, in real time thanks to CT fiber-optic telemetry. Those downhole pressure readings further assist in optimizing the pumping rate during the job, while keeping it below the fracturing pressure. Finally, the telemetry provides support for gamma ray (GR) logging, which facilitates depth control and lateral identification.

This study features a case history during which the matrix stimulation treatment was conducted in two separate CT runs for both laterals of the well. For the first run, the CT initially entered L-0 following the natural path of the well, whereas L-1 was accessed by activating the LIT. Correct lateral entry was confirmed by matching the acquired GR readings with reference logs. After successfully accessing L-1 and reaching its maximum depth, a ¾-in. ball was dropped to isolate the LIT and activate the HPJN for stimulation.

During the second run, as the CT entered L-0, GR monitoring was used to confirm lateral accessibility. The stimulation treatment was pumped after reaching maximum depth and isolating the HPJN. During the stimulation of each lateral, 20% viscoelastic diverting acid was utilized for diverting from high-intake zones and 20% HCl to stimulate damaged/tight zones.

This operation illustrates how downhole pressure gauge readings are used to sequentially operate the LIT efficiently and activate the HPJN, as well as to pump the matrix stimulation treatment below the fracturing pressure. Real-time GR readings, meanwhile, are used for depth control and to correctly identify laterals.
Use of Legacy and Real Time Data to Overcome Anti Collision Challenges in Highly Congested Fields, Onshore Abu Dhabi
Authors: Dutta Ashim , Stefan Aillud Gary , Bermudez Martinez Rafael , Al Hosani Mariam , Jaiyeola Abiodun , Alejandro Aranda Jose , Al Mansouri Ibrahim , Ahmed Baslaib Mohamed , Al Bairaq Ahmed
Published: November 2018

Decades of field development in onshore Abu Dhabi fields has resulted in significant operational challenges in planning and drilling new wells. These highly congested fields pose a high risk of well collision due to inherent range errors in the accuracy of well survey measurements obtained during the life of individual fields and reservoirs. The study discusses a methodology for improving and normalizing the accuracy of legacy wellbore survey data to aid successful planning of recent multilateral drain hole strategy and how real time data corrections can aid in accurate wellbore placement.

Multilateral wells are risked by higher collision issues for having target areas in separate azimuths from single surface location (SL). Proposed wells were subjected to lower Separation Factor (SF) due to high density of wells. In the study area, survey data of existing vertical and horizontal wells in upper and lower reservoirs in the proposed well path were studies and plotted in well sections and maps in Geological model. Well anti-collision runs of proposed lateral holes with offset wells were done in drilling planning softwares. A notional model study carried out with one of the proposed triple lateral wells in ADNOC Onshore with nearest offset wells with MSA and SAG correction resulted in collision risks being reduced by 52% and hence qualifying with the minimum SF required for safe drilling.

Recent reservoir development strategy in an Abu Dhabi Onshore field is to drill trilateral wells targeting multilayered reservoirs to maximize production while optimizing sweeping efficiency. Well survey quality management with In-Field Referencing (IFR), Multi Station Analysis (MSA) and SAG Correction are the primary steps to be applied to MWD survey measurements to reduce the well collision risk. The normal well anti-collision study with nearest offset wells is mandatory as per standard drilling practices and with densely populated wells in one of the giant Abu Dhabi Onshore fields, it is becoming challenging to meet the minimum separation factor (SF>2) required by the company policy.

A survey correction in all legacy wells followed by real time survey correction in triple lateral wells will add a significant value concerning collision issue in the proposed triple lateral campaign. With growing number of wells in highly congested fields, Pad drilling coupled with advance survey management technique will result in high value addition for future drilling campaigns without having collision risks and hence pave the way for future infill development strategy without subsurface space constraint.
Human Factors in HSE Performance: Using Brain Science to Guide Behavioural Developmental, Pro-Active Talent, Capabilities and Potential for the Long Term
Authors: Jahne Peter
Published: November 2018

We strive for excellence. Such excellence continuously moves to higher standards and to cover more scope. Using another terminology, it is about continuous improvement built upon the realization from learning through experiences. With this as our guiding concept, the long-term value is about developing a framework that drives itself towards enhancement, towards self-governance.

The HSE preparedness standards are guided by the capability to predict scenarios of the future. Specifically, context-shaped scenarios based on very focused activities that include the environmental (nature), material (equipment & tools), procedural (operating processes) and the human (mindFLEX) dimensions. The core element towards superior HSE standards remains at the human level - the core. It is the individual / group mental and behavioural capabilities that become the blueprint, the engine, the calibrator and enhancer of HSE.

If operational excellence is the objective, the people behind it are to sculpture its shape, define its course and develop a behavioural internalization programme. Their behavior then becomes the expression of what their brain is made of. It is therefore the objective to assess, develop and guide brains to have what it takes towards HSE excellence.
Step Change in Reservoir Monitoring in Complex Borehole Environments
Authors: Bin Noordin Firdaus , Mosse Laurent , Albuali Abdullah , Dasgupta Suvodip , Raina Ishan , Zhou Tong
Published: November 2018

Reservoir monitoring carried out using previous-generation pulsed neutron logging tools worked well in ideal borehole conditions. However, evaluations were complicated in non-ideal borehole environments, such as gas in the borehole, which affects capture cross section, sigma, and thermal neutron porosity measurements, changing borehole fluid holdup, which confuses carbon-oxygen interpretation, and identifying hydrocarbon type using only neutron porosity when oil density and hydrogen index are very low or open hole (OH) data are unavailable.

A new-generation pulsed neutron logging tool has been introduced that benefits from a high output neutron generator, two LaBr3 detectors, one yttrium aluminum perovskite (YAP) detector, one neutron source monitor, and an improved acquisition sequence. It provides self-compensated measurements of sigma and thermal neutron porosity, along with full capture and inelastic spectroscopy, including total organic carbon (TOC) and carbon-oxygen ratios. This tool also measures a new formation property called the fast neutron cross section (FNXS), which provides a gas saturation estimate independent of conventional methods. All measurements are recorded in the same logging pass, thus reducing overall logging operation time.

Pulsed neutron measurements were acquired in lateral wells using the new generation tool in the A field, onshore Abu Dhabi. Through lateral sections with changing oil, water, and gas holdups in the borehole, and in changing completion environments, robust sigma and neutron porosity measurements were acquired with the help of the automatic self-compensation algorithm. Neutron porosity helped quantify gas saturations where the OH data are available and of good quality. However, in zones where it is not possible to use the neutron porosity by itself (for example, in zones with missing or uncertain OH results), the FNXS measurement provided an independent estimate of gas presence and saturation. FNXS of brine (7.5 1/m), calcite (7.5), and oil (6.0 to 7.0), are similar and strongly contrast with the FNXS of gas (1.5 to 2.5). Thus, the measurement is insensitive to porosity by itself but highly sensitive to gas presence. A crossplot of thermal neutron porosity (TPHI) and FNXS provides a robust estimate of gas saturation in wells where OH results are uncertain or not available.

This paper presents, through multiple examples, a first comprehensive look at the various challenges faced while logging lateral wells in a light oil environment and showcases how a combination of self-compensated measurements coupled with the new measurement of FNXS can make data interpretation more robust in complex borehole and completion environments.
Application of Interwell Partitioning Tracers for Evaluating the Effectiveness of Chemical EOR in Field A in Southern Sultanate of Oman: A Case Study
Authors: Guntupalli Suryanarayana , Chatterjee Monalisa , Svec Yi , Al-Shuaili Khalfan , Amri Mohsin , Pugla Sarika , Hewitt Paul
Published: November 2018

This paper discusses a case study including the design, implementation and results of an Interwell Partitioning Tracer Test (IPTT) to measure incremental oil recovery from an ASP flood in a major sandstone reservoir in a field (Field A) in Southern Oman operated by Petroleum Development Oman (PDO).

Conservative tracers have been used over decades to evaluate conformance of a flood in reservoirs. Chemical tracer research and development as well as enhanced interpretation capabilities lead to the availability of a number of unique chemicals that allow remaining oil measurement to be routinely measured at the pattern and field level.

An inverted five spot pattern pilot area was chosen in Field A to apply interwell partitioning tracers with three time lapsed IPTT surveys between February 2014 and January 2017 to quantify desaturation by ASP. First, one unique passive tracer was injected in a central injector of an inverted 5 spot pattern flood to study the conformance of waterflood within the pilot area prior to an ASP application. The second stage was carried out during the pre-ASP water flush where one passive and two unique partitioning tracers were employed to estimate the remaining oil saturation after waterflood within the pilot immediately prior to the ASP flood. The third phase was initiated post the ASP flood where one passive and two unique partitioning tracers were added along with chase water. This final step was aimed at evaluating the effectiveness of the ASP flood through estimation of residual oil saturation within the water contacted pore volume between wells.

The resulting passive and partitioning tracer curves were assessed for their difference in retention times related to the amount of remaining oil saturation and tracer solubility in oil and water. The partition coefficient values were measured at reservoir conditions in a specialist laboratory that was used to estimate the average pre-and post-ASP flood oil saturation within the flooded pilot area of Field A. The results of the study showed an excellent reduction in oil saturation by about 30% within the pilot area. Desaturation level in the pilot determined by IPTT was consistent with other methods.
Performance Evaluation and Field Trial of Self-Adaptive Microgel Flooding Technology
Authors: Sun Zhe , Kang Xiaodong , Tang Xiaoxu , Wu Xingcai , Li Qiang , Wang Yu , Wang Tianhui , Zhang Hong
Published: November 2018

Bohai offshore oilfield in China is characterized by high oil viscosity, strong reservoir heterogeneity and big inter-well distances, which leads to the breakthrough of injection water in deep reservoirs with poor sweep efficiency and development effect. To solve this problem, this paper evaluated the performance of self-adaptive microgel system (SMG), and introduced its application in field trial.

The self-adaptive microgel is a kind of microsphere in various sizes with strong deformation ability. In this paper, the physical and chemical properties of the self-adaptive microgel are studied by means of metallographic microscope and the statistical principle. Also, the extreme permeability value of the self-adaptive microgel which allows it to flow though the core is determined through core flow experiments and the evaluation method of resistance factor and residual resistance factor. Furthermore, a long core is used to evaluate the fluid diversion ability of the self-adaptive microgel under the condition of constant speed and constant pressure flooding. Finally, a field trial case study of the self-adaptive microgel is analyzed.

Experiment results suggest that the self-adaptive microgel has good water swelling properties, narrow particle size distribution, huge inaccessible pore volume and large accessible pore volume of its carrier fluid. When the self-adaptive microgel with micron and submillimeter particle size flow through the core and the injection pressure stays stable, the permeability limit is 237×10−3μm2 and 712×10−3μm2, respectively. Since the self-adaptive microgel enters larger pores and generates plugging effect, while its carrier liquid enters smaller pores and displaces oil. So it obtains combined effects of "plugging" and "flooding". Moreover, the oil increment of the self-adaptive microgel under constant pressure flooding is higher than that under constant speed flooding. The case study shows that self-adaptive microgel flooding can increase oil production and reduce water cut obviously, which obtains technical and economic success.

Also, this paper preliminarily establishes a property evaluation method for the self-adaptive microgel, analyzes its mechanism and displacement effect. Furthermore, the field trial effect of self-adaptive microgel flooding is explored. In summary, the research results provide a theoretical basis and technical support for the application of self-adaptive microgel flooding technology.
Considerations of Pipeline Crossing Design
Authors: El-Chayeb Abdul Rahman , Wang Don , Kamal Faris , Takieddine Oussama
Published: November 2018

Pipeline crossings are an integral part of brown field developments and their design for shallow water conditions poses a number of challenges which require special considerations. Hydrodynamic stability and Vortex Induced Vibration (VIV) are typical examples. For both of these design aspects, there is no specific design criteria and methodologies dealing with crossings as is the case for pipelines resting of the seabed which, among other codes and standards, are covered by DNVGL RP F109 and DNVGL RP F105 for stability and VIV respectively. In the absence of specific design criteria, the industry have relied on interpretations of existing codes leading to crossing designs with varying failure probabilities and safety levels for different projects and different operators.

This paper discusses the main aspects of pipeline crossing design in shallow water conditions as is the case for the Arabian Gulf Region. In this region, the water depths could be close to the limits of applicability of the conventional design codes which were established based on experiences and considerations for other geographical regions. As a result, the design of crossings poses an engineering challenge as the calculated allowable span lengths tends to be short and the number of supports greater than what can be reasonably constructed for the pipeline to sit on all supports. The viability of using design criteria adapted from these codes for VIV is assessed using full dynamic simulations taking into account the compressive axial loads in the crossing. It is shown that for the short crossing spans, which are typical in the shallow water of the gulf region, the onset of any VIV will result in phenomenon which is called here "crosswalking". This crosswalking will result in a lateral displacement of the pipeline over the crossing sleepers resulting in an increase in the first natural frequency due to the reduction in axial compressive loads and the change in behavior from beam to shallow arch.

Implementing the analysis procedure discussed in this paper and taking into account the potential for crosswalking will help increase the length of the crossing spans. This increase can be to a level where the hyperstatic conditions can be eliminated and the crossings can be designed to be construction friendly. This will have direct cost and schedule impact on the execution of brown field developments where crossings constitute a major element of the project. It is hoped that further work will be done on studying the VIV of pipeline spans and crossings under axial compression as this area of pipeline engineering has not been fully explored and the focus of VIV research has been directed to risers which are always under axial tension.
Value of Condition Monitoring Data in Safety Management Decision Support
Authors: Jeeves Simon
Published: November 2018

ValveWatch can be a powerful tool as part of an operational strategy, as it provides valuable information that can be used to track operational Safety according to IEC 61511/508 (Functional Safety Assessment - SIL – Safety Integrity Level).

Within an operating plant, Functional Safety Management for automated on/off valves, PSVs and manual valves it is required to understand why the valves fail and how it is possible to mitigate these failures. The common factor is that the Faults that one has experienced i.e the valve/actuator has failed to carry out its intended task has caused a loss in production or a reduced the level of safety that the plant has been operating under. – These are expensive lessons and lessons that are repeated often.

The reason why these "lessons" get repeated is because the failures that have been experienced are due to hidden failures that are not possible to discover with traditional instrumentation (I.e limit switch, Partial Stroking, opening/closing time). In the terms of IEC 61508 these faults are categorized as DU Faults (Dangerous Undetected). Often these faults may have been introduced due incorrect maintenance, incorrect operation of the valve/actuator or simply due to wear and tear.

Critical valves have requirements with respect to functional testing and also perhaps through leakage tests. The manual methods in testing are flawed and it is difficult to uncover the DU's and even the DD (Dangerous Detectable Faults). Furthermore, the manual tests are often carried out when there is no pressure present, hence the valve is not tested under realistic conditions.
Case Study of Pilot Application and Efficiency Analysis of Waste Heat Recovery from Gas Engine Generator Jacket Cooling Water to Heat Waxy Multiphase Fluid at Offshore Platform
Authors: Kenoth Sasidharan Adiyodi , Kottappuram John , Henry Samuel Isaac
Published: November 2018

The oil and gas industry is in continuous look out of innovative means to improve the efficiency of its energy-intensive oil- and gas-processing operations through improved energy use and waste-heat recovery. This paper details about an integrated pilot application of two waste-heat-recovery units designed and implemented in an Offshore platform off Caspian Sea. Actual results are compared with simulation / design results. A thermodynamic analysis of a gas generator engine waste-heat-recovery cycle is carried out.

The offshore platform has a water injection plant supporting water flooding project for reservoir pressure maintenance. The Sea Water Lift and Main Injection Pumps are powered by multiple Gas Engine Generators of @ 1000 kW power rating. The exhaust gas from each of these gas engine contains approximately 10 million Btu/hr recoverable heat. Also the heat energy from the jacket cooling water used for engine cooling is used for heating the waxy crude oil and natural gas. A Shell & Tube Heat exchanger is used for recovering the heat energy.

By utilizing the heat energy of flue gas and jacket cooling water the energy efficiency of gas engine can be doubled from 35% to 75 %. Two such Gas Generators with Heat Recovery system has been introduced which collectively creates an energy saving of approximately 1500 KW daily for crude oil heating. Approximately 8000 bbl oil with 100 scf/bbl gas oil ratio was able to heat to get a temperature differential of 25-35 degree C. The cooling water temperature was dropped to 60 degree C.

With rising fuel costs, energy conservation has taken on added significance. Installation of waste heat recovery units (WHRU's) on gas turbines is one method used in the past to reduce gas plant fuel consumption. More recently, waste heat recovery on multiple reciprocating compressor engines also has been identified as having energy conservation potential. This paper reviews the development and implementation of a WHRU potential. This enhance hydrocarbon recovery, and reduce utility cost in a plant.

In an era when energy conservation and fuel shortages are not uncommon, mechanical systems designed to improve the thermal efficiency of fuel-consuming equipment have become a necessity. This paper presents an energy efficient process and mechanical design along with footprint saving.
9.2 MW GLC Compressor Motor Starting – Use of Induction Motors
Authors: Manna Malay , Kotrappa Murugendrappa N. , Al-Ammari Sara Jamal
Published: November 2018

The electric motor for the Gas Lift Compressor is 9.2 MW, 4-pole construction, and induction type. The motor rated voltage is 11kV, fed from 33kV switchgear via a captive 33/11.5 kV, 15 MVA transformer.

A review has been performed to examine the feasibility of the gas lift compressor (GLC) motor starting with below starting methods, and to highlight advantages and disadvantages among the starting methods: –With pony motor during motor start-up–Direct On Line (DOL)–With additional auto-transformer

The study results indicated that the GLC motor is able to start up successfully with either type of above motor starting methods.

Motor starting with pony motor is technically feasible. However, the pony motor starting method is not a common practice for induction motor, it requires additional equipment including pony motor, 415V VFD for the pony motor and MV Panel with Capacitor Bank.

Motor starting Direct On Line is the simplest option; it takes the advantage of the mechanical variable speed drive (Vorecon unit) design, i.e. the motor and the compressor is disconnected during motor starting, and the motor starting loading torque is limited below 5% of rated load torque. The motor is able to start up successfully with acceptable upstream bus voltage dip during normal operation and even when one major component of the power system network is out of service. In the cases with two or three components of the power system network out of service, the motor is still able to start up with upstream bus voltage dip exceeding the project limit but less than 15%. This is considered acceptable technically as the other running motors will not stall.

Motor starting with additional autotransformer will improve the upstream bus voltage dip during motor starting marginally, but further extend the motor starting duration.
Rigless Pulling Unit - First Time Worldwide, A New Concept for Workover and Recompletion
Authors: Sreeroch Asadawut , Nicolson Don , Abu Jafar Feras , Charoensil Teeranun
Published: November 2018

In a global first, Mubadala Petroleum in Thailand has successfully completed a three-month trial of a new technology designed to improve the operational performance of the regular program of well maintenance workovers required for its Gulf of Thailand fields. The trial tested the use of an innovative modular Rigless Pulling Unit (RPU) in place of a conventional Hydraulic Workover Unit (HWU) in a program of workover operations.

Historically, the RPU used by most operators worldwide for Plug and Abandon (P&A) type of operation. However, Mubadala Petroleum has pushed the technical limits for the RPU to perform ESP change out and running upper/lower completions (Re-completion) on existing wells that has ESP failures, or any recompletion opportunities.

During the trial period, this new unit achieved similar operational efficiency to a HWU, while proving its capabilities to execute the most complicated tasks that are challenging even for the HWU, in terms of reducing rig time, well cost, and most importantly minimizing the HSE risks. This technology can be developed to be a "fit for purpose" intervention method for the future workover, recompletion and decommissioning activities. The utilization of RPU for a long well services campaign, for post-drilling completions, for slot recoveries and for a decommissioning campaign will have more potential of cost saving vs using the Rig or HWU.

With this first worldwide successful trial of a RPU for well workover operations, we have opened the doors for new opportunities to perform workover activities other than with standard hydraulic workover rigs. The RPU technology offers many advantages and capabilities to perform more efficient complex workovers or recompletion operations.

Material presented is from actual workover operations, including electrical submersible pumps (ESP) change outs and cycling lower completions, wellbore cleanout, etc. It will also display the operational efficiencies increase and risk reduction achieved.
Maintenance Job Plan Alignment Using 5S Lean Process
Authors: Sianipar Tumpal , Pande Girish , Thonnan Thodi Shameer Babu
Published: November 2018

As part of the ADNOC Gas Processing Sustainability Program – Enhance Maintenance Strategy, the review of Maintenance Job Plans across all sites was one of the top action items for implementation. The objective of this task was to align the maintenance practices to achieve an agile, efficient and fit-for-purpose maintenance program across all sites. This included the review of job plan activities, man-hours and skill level.

The lean management process with 5S was adopted for the implementation of this task; the process was progressing through the cycle elements i.e. sort, set, shine, standardize and sustain. The "As-is job plans" were segregated by equipment type during the "Sort" stage. The order of review priority was set based on the highest manpower spent using the Pareto principle. Non-value added tasks were removed during the "Shine" stage. The job plans across all sites were then aligned to deliver "To-be job plans" which brings in a standardized approach. To ensure the standardization across all sites, the job plan codification procedure was developed. Such job plan codes library will be centrally controlled and updated by the focal point who will be the custodian of corporate job plans. In the "Sustain" phase, periodic reviews will be conducted to ensure sustainability over current and future of asset maintenance practices.

As the quantum of job plans to be reviewed was very large, the task was divided into two phases. The first phase included a review of quick win items that covers job plans that spent 80% of man-hour, while the 2nd phase was for the remaining job plans. Phase-1 has been completed successfully which included pre-defined 10 equipment type. Phase-2 is well in progress, slated to be completed by quarter 4 of 2018.

As a result of the phase-1 project, the numbers of job plans were significantly reduced to 119 from 3851 which contributed to man-hour optimization of approximately 15 %.

This task enabled us in aligning the practices across the sites, optimizing man-hours in asset maintenance and achieving synergy in maintenance policy adoption. This task will eventually lead us to have optimized, comparable and fit-for-purpose maintenance practices at all sites, which will improve the efficiency and profitability of the maintenance organization.
Holistic Study to Identify Root-Cause of Corrosion in Christmas Trees of Oil Producer Wells
Authors: Kumar Amit , Al Dahmani Ahmed , Kunhi Shaheen , Iqbal Asif , Amad Muhammad , Morrow Timothy
Published: November 2018

During field inspection of Christmas (X-mas) trees in a giant oil offshore field in Abu Dhabi, a small subset of wells were reported to be severely corroded on X-mas tree studded outlets imposing high HSE risks due to possible loss of containment. A holistic analysis was conducted to identify corroded X-mas trees, establish the root-cause of corrosion and recommend a remedial action plan to control future corrosion damage and reduce HSE risk exposure.

Advanced modeling tools and lab tests were used to analyze the flow behavior and field samples, respectively. Advanced modeling was performed to analyze inorganic scale potential, identify flow regimes and calculate corrosion rates in the X-mas trees to correlate with operating conditions. Solid samples from X-mas trees were analyzed using advanced microscopy techniques to identify the elemental composition and phases. Water samples were also analyzed to check bacteria content. Available data on historical operating conditions, modeling and lab analysis results were segregated into in-favor and against factors for each of the mechanisms to identify the potential root-cause of corrosion. Modeling results were used in conjunction with actual field data such as corrosion feature morphology, historical operating conditions, etc. to evaluate corrosion damage. Based on corrosion feature morphology, wells were categorized into different groups to compare the flow behavior and operating conditions with observed corrosion patterns.

A thorough analysis of corrosion feature morphology and operating conditions identified flow-induced localized corrosion (FILC) as the root-cause of corrosion in severely corroded X-mas trees. X-mas tree design, fluid properties and operating parameters such as well head pressure (WHP), wellhead temperature (WHT) and flow rate were found to be key contributing factors of accelerated corrosion. Results of computational fluid dynamics (CFD) modeling showed that the horizontal section of X-mas tree is exposed to higher turbulence, water wetting and transient gas bubble formation/collapse phenomena than the vertical section due to changes in flow direction and gravity effects. Several mitigation strategies were implemented to control corrosion in the X-mas tree flange area, and reduce likelihood of leakage through the X-mas tree flange. Findings from this work led to development of an Excel based tool which can be used to assess and predict the corrosion risks to X-tree based on operating conditions.
Best Design & Engineering Practices to Enhance Centrifugal Compressor Reliability
Authors: Abbas Zafar , Kumar Yogesh
Published: November 2018

Centrifugal compressors are vital part of industry due to wide range of their application and operating flexibility. However several challenges are encounterd in all phases from FEED, construction, commissioning to smooth operation. ADNOC-onshore Sahil oil and gas production facility has gone through major expansion in 2013 allowing to enhance its production capacity by 55%. During FFD commissioning and start up of centrifugal compressor during FFD has been challenging. Several breakdowns, equipment & auxiliary failures and start up hurdles have been faced, which extended equipment shutdown durations to few weeks causing the O&G production company to loss thousands of barrels of oil production and hence suffer huge financial loses. During the course of time several innovative solutions were devised and successfully implemented to address these challenging issues. This paper describes these failures with solutions, which are common with similar machines, so that these vital interventions are considered and integrated into design and engineering practices to enhance centrifugal compressor reliability. Critical part of this problem is sub-vendor's provided components and subsystem. These systems have been seen to have performance and capacity issues along with deisgn and safety system incompatibilities. Maintenance, inspection and replacement of such parts are challenging for O&G production companies owing to local market constraints and vendor unavailability.

Design and engineering practices by OEM, EPC, sub-supliers and oil & gas production companies need immense improvements for bumpless commissioning and startup of such critical equipment. A multi-descipline engineering team from manufacturer, constrction and O&G producuction & process companies with very specific responsibilities pertinent to design, construction and operation reviews at all stages, would play vital role to overcome such issues.

This team would closely monitor all key activities for precision and design amendments, during construction-commissioning, startup and smooth operation phases, in order to avoid these issues in 1st place. This would results in tremendous savings(in terms of losses minimization and early & smooth production) to the O&G producuction Company as well as all involved vendors and Construction Company, by timely commissioning the compressor, ensuring smooth start up and maintain bumpless operation.
Three-Phase Flow Visualization and Characterization for a Mixed-Wet Carbonate Rock
Authors: Scanziani Alessio , Alhammadi Amer , Bijeljic Branko , Blunt Martin J.
Published: November 2018

A novel method is presented to characterise in situ three-phase flow, including wettability, pore occupancy and displacement mechanisms, at the pore scale. We used X-ray microtomography to obtain 3D images of a carbonate reservoir rock saturated with crude oil and formation brine at subsurface conditions. The sample had been aged with crude oil from the same reservoir to replicate the sunsurface wetting conditions. The pore occupancy analysis shows that brine is non-wetting to oil and gas is non-wetting to brine with a wettability order of oil-brine-gas from the most to the least wetting fluid. The waterflood recovery after 1 pore volume injected was only 14%, but this increased to 48% after further gas injection. New multiple displacement mechanisms were observed, with gas displacing brine, which in turn displaces oil. The results from this work can be used to improve the prediction accuracy of the three-phase network models and helps in the design of gas injection processes.