bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi Functional Pipeline Systems
Authors: Critsinelis Antonio , Mebarkia Sid , Lundeen Kale , Kalia Akshay , Skowronek Tyler , O'Neill Eoghan , Zeid Hosam Abu
Published: March 2018

Long-distance tiebacks are becoming more prevalent for subsea projects and present many unique challenges for successful operation. Flow assurance challenges arising from different operational regimes as well a high capital cost for enabling reliable production pose a unique challenge for long-distance tiebacks. A potential mitigation is the use of a pipe-in-pipe system for insulating purposes.

The multifunctional pipeline system (MFPS) aims to provide further functionality and flexibility to the pipeline system by utilizing the annulus of the pipe-in-pipe system as an additional transportation line thus, providing the flexibility and added functionality to the pipe-in-pipe system to increase operational flexibility, reduce capex and opex, and improve system availability to drive capital efficiency. The MFPS station can also be used to detect a plug location, monitor pressure on both sides of a plug, circulate hot fluid in the annulus and bypass the affected section. This technology was developed in joint collaboration with Chevron and Schlumberger.

This paper will highlight the overall functionality of the MFPS, the concepts that were investigated during the development of the MFPS, and the benefits that each unique concept provides to the overall field architecture.
Numerical Modelling of Methane Hydrate Dissociation in Sandy Porous Media by Depressurization with a Parametric Study
Authors: Yin Zhenyuan , Moridis George , Tan Hoon Kiang , Linga Praveen
Published: March 2018

Due to its increasing abundance, cleaner and lower emissions upon combustion, natural gas (NG) has been considered as the best transition fuel away from coal and oil to a carbon-constrained world. Methane gas is the major component in NG accounting for 70-90%, and is also the major constituent found in natural gas hydrates (NGHs). The amount of CH4 preserved in NGHs is vast and estimated to be 20,000 trillion cubic meter (TCM) worldwide. This outweighs the proved NG reserve on earth, which is 865.4 TCM, and doubles the combined reserve of all fossil fuels. Thus, NGHs have been considered as a potential future energy source. Extensive geological surveys and drilling programs have been carried out during the past two decades at various countries (Canada, USA, Japan, S. Korea, India, China, etc.) to identify the location of these NGH reservoirs, to quantify the amount of gas deposited and to recover hydrate cores to analyze their thermophysical and geomechanical properties. Extensive research have also been carried out in laboratories to synthesis gas hydrate mimicking marine and permafrost conditions, and to study their fundamental behavior of formation and dissociation. In this study, we numerically analyzed an experiment of methane hydrate bearing sediment (P = 6.2 MPa) with hydrate saturation SH = 40% dissociation process induced by depressurization (P = 4 MPa) in a 1.0 L reactor with the production of water and gas. The simulation-predicted cumulative gas production shows an excellent agreement with the experimental measurement. In addition, from the evolution of phase saturation over time, it is revealed that hydrate dissociates from outer boundary to inner core. In addition, methane gas migrates to the reactor outer boundary first and accumulates to the upper section of the reactor mainly due to buoyance effect, while water drains down to the bottom of the reactor due to gravity. The parametric study on the fulids and thermal transport parameters (absolute permeability, k and HBS composite thermal conductivity, kθ) and the kinetic parameter (K°) concluded that the gas production process is predominated controlled by thermal and kinetic reaction paramters, while flow paramters does not play a significant role in the current smallscale reactor.
An Integrated Multi-Scale Numerical Simulation of Transient Gas Flow in Shale Matrix
Authors: Zhan Jie , Soo Eric , Fogwill Allan , Cheng Shiqing , Cai Hua , He Ruijian , Chen Zhangxin
Published: March 2018

The gas flow in shale matrix is of great research interest for optimizing shale gas development. Due to a nano-scale pore radius, the gas flow in the shale matrix may fall in flow regimes which include viscous flow, slip flow and Knudsen diffusion. On top of that, gas adsorption/desorption and stress-sensitivity are some other important phenomena in shale. In this paper, we introduce an integrated multi-scale numerical simulation scheme to depict the above phenomena which is crucial for the shale gas development.

Instead of Darcy's equation, we implement the apparent permeability in the reservoir-scale continuity equation to depict the gas flow (viscous flow, slip flow and Knudsen diffusion) in shale matrix. A Langmuir adsorption/desorption term is included in the reservoir-scale continuity equation as a generation term. To ensure the real-time desorption and adsorption equilibrium with gas production, an iterative mass balance check of pore wall surfaces (pore scale) is introduced. At each time step, the pore-scale and reservoir-scale mass balance should be satisfied simultaneously in each grid block. On top of that, the lab data of a Bakken reservoir which provides a relationship between a matrix pore radius reduction and the effective stress is integrated into the two-way coupling geomechanical process to simulate a stresssensitive shale formation.

This methodology examines the influence of each mechanism for the shale gas flow in the matrix. Instead of conventional pressure-independent Darcy permeability, the apparent permeability increases with the development of a shale gas reservoir. With the gas adsorption/desorption, the reservoir pressure is maintained via the supply of released gas from nano-scale pore wall surfaces. With the consideration of geomechanics, the apparent permeability is decreased due to the compaction of nano-scale pore radii, which leads to the maintenance of reservoir pressure. Due to the difference of compaction magnitude for each grid block, geomechanics create additional heterogeneity for a nano-pore network in shale matrix, which we should pay more attention to.

A novel integrated multi-scale methodology is introduced to examine the crucial phenomena in the shale matrix, which simultaneously takes into account the influence of flow regimes, gas adsorption/desorption and stress-sensitivity. An effective way is provided to quantify the above effects for the transient gas flow in shale matrix.
Big Data Analytics for Micro-Seismic Monitoring
Authors: Joshi P. , Thapliyal R. , Chittambakkam A. A. , Ghosh R. , Bhowmick S. , Khan S. N.
Published: March 2018

Big data technology is applied to analyze massive micro-seismic data set, which incorporates previously over-looked data set. This, in turn, will give redundant fracture modelling in stages and exact fracture propagation map in real time. Micro-seismic is pivotal to the success of Hydraulic Fracturing activity. However, with the advent of advanced geophones, the massive dataset requires a different analytical point of view, currently absent in conventional database processing and algorithms. HADOOP equips with the necessary tools for better and advanced real-time processing and analysis.

Various Algorithms are developed to show comprehensive fracture operation analysis. Previous job failures are used to predict future anomalies, hence enhancing success ratio. The holistic dataset for the reservoir (Exploration, Drilling, and Production) are considered to synchronize the reservoir information. For example, drilling data (ROP, drillability, WOB etc.) is analyzed to predict the type of formation (like Brittle or Ductile), poroelastic constant, elasticity etc. Comprehensive analysis of fracture propagation would consider all the parameters associated not just conventional ones.

The dataset is stored in Hadoop and called upon whenever needed. The massive amount of dataset is not being processed in conventional databases but can be integrated using Hadoop. The analytical results provided from Hadoop stands out from conventional formulae based software. The visualization of results keeps the minimum scope of error contradicting with the currently used ones. In current ones, many data trends and parameters are left out which are not used in formulae. Those patterns are visually shown and incorporated into the analysis, causing better mapping of fractures. Not only just complementing current analysis, Big Data provides the scope of comprehensive analysis from start to end. When 3D seismic appeared, it was a radical change. It not only showed 2D maps were of low resolution, rather those were rendered misleading. The Hadoop analytics is providing a unique perspective, leaving some mismatches, which are needed and to be seriously considered for future planning.

The resulting model does not use conventional formulae, hence not limited to consider the real-time data. Rather field data (associated with noise) is analyzed using algorithms, generating trends from noises and deviations. The conventional software misses massive relevant data, which apparently cannot be incorporated into formulae. That inability is being met with Big Data analytics. Conventional database management is unable to handle so much data, which are being taken care off by Hadoop platform.
Development of Supercritical CO2 Mineral Carbonation Technology for High CO2 Fields Development
Authors: Noh M Ghaddaffi M , Onn M Syazwan , Berahim N Hafizah , Mumtaz Hazratul
Published: March 2018

Development of ultra high CO2 field in Malaysia is the next frontier as far as contaminated green field development is concerned. Large hydrocarbon reserve is a major driver to mature technology to support the development of contaminated fields. However, managing the contaminant CO2 is still a major drawback as far as technology is concerned. Base case consideration for CO2 emission mitigation for offshore high CO2 gas fields had always been geological injection even though it deteriorates the overall field economics to a point which may prove to be prohibitive for some field development cases. An alternative method to mitigate CO2 would be the conversion of CO2 to higher value products which provides return in the form of additional revenue or profit. The monetory income from the conversion of CO2 can be utilized to either fully or partly offset the high cost of CO2 injection. This paper attempts to summarise the experience based on feasibility study, technical consideration and lesson learnt by PETRONAS to mitigate the CO2 emissions from the development of such high CO2 gas fields. The summary is done in the context of selecting the suitable CO2 mitigation technology, scale of conversion, maturing the technology and economic consideration as an integral part of the field development.
A Play-Based Evaluation of a Deepwater Sabah Exploration Area: Prospect Maturation and Implications for Remaining Prospectivity
Authors: Abdullah Siti Aishah , Barker Steven M. , Jong John , Watanabe Yoshiaki , Bakar Dayang Aimi Nuraini Awang , Khamis Mohd. Asraf
Published: March 2018

This study presents a play-based evaluation of the southern part of the deepwater NW Sabah fold-thrust belt, a key exploration area in Malaysia. The key objective was adding value to the existing database through an integrated approach. This goal was achieved by analysing four critical geological risk elements: reservoir presence, structural evolution, top seal integrity, and timing of hydrocarbon charge and migration, to identify prospective areas for future exploration by integrating all available geological, geophysical and geochemical information into a consistent petroleum system framework. Using the basin-play-prospect maturation workflow, data spanning the geophysical domain (with inputs such as seismic evaluation, structural mapping and attribute analysis) to the geological realm (such as well correlations, fairway mapping, sedimentological studies, biostratigraphic investigations and source rock maturation modelling), are combined with structural kinematic evolution to generate detailed play-based element maps. The application of the tried and tested play-based evaluation methodology from basin evaluation through to prospect maturation has been carried out. This has led to a comprehensive play element analysis yielding a composite risk segment map within a consistent petroleum system framework. In addition, the study has provided sensible explanations for dry hole analysis, an important reality check, but most importantly it has generated a fresh insight into the overall prospectivity of the study area. This enhanced multi-discipline analysis is beneficial for reducing exploration risk for future expenditure in a time of depressed oil prices that calls for a more innovative approach for deepwater exploration. In summary, integration of available data and the application of new in-house ideas and solid geoscientific knowledge has added value through the generation of increased prospectivity, however for further ground-truthing the real litmus test has to come from future drilling.
Estimating Storm Surge And Reservoir Subsidence Of Offshore Platforms Using WaveRadar REX SAAB Sensors
Authors: Anokhin Vadim , Ewans Kevin
Published: March 2018

WaveRadar REX (SAAB) instruments are widely used in the offshore oil and gas industry for wave, tide and air gap observations. This study extends the application of WaveRadar REX to the estimation of storm surge and reservoir subsidence from long-term water level measurements. AirGap data from several offshore fixed steel platforms offshore Borneo island (South China Sea) were analysed, yielding waves, astronomical tides, Sea Surface Anomalies (SLAs), which included storm surge and changes to water level due to long-term climate variability. Vertical platform movements, which can be attributed to reservoir subsidence and Vertical Land movements, were also derived. The storm surge estimates were consistent with values reported for the region, with positive storm surge (+0.3m) peaking in November and December, at the onset of winter western North Pacific Monsoon and northeasterly winds; negative storm surges (-0.2m) were recorded from March to July, coinciding with the boreal summer East Asian Summer Monsoon and southwesterly winds. Locations further offshore showed marginally lower storm surge compared to the coastal stations. Along the coast of Borneo, there was a shift in the timing of the positive storm surge arrival offshore Sabah, with establishment of positive storm surge shifted forward by about a month. Lastly, trends of SLAs derived from WaveRadar REX AirGap can be used to monitor long-term Vertical Land Movements and offshore platform subsidence. The comparison of AirGap subsidence estimates against independent dGPS measurements of vertical platform movement showed excellent agreement for several offshore platforms, all results within 0.05m accuracy. The new technique offers a cheap and reliable method of continuous vertical subsidence monitoring of fixed offshore platforms using instrumentation routinely installed offshore, thus offering an alternative to dGPS subsidence monitoring.
Using Play-Based Pore Pressure Prediction to Avoid Geohazards and Discover Successful New Play Concepts
Authors: Tingay Mark
Published: March 2018

‘Play-based Pore Pressure Prediction’ is a new concept that considers overpressures and pore pressure prediction as being a fundamentally similar process to the ‘play-based exploration’ approach commonly used to search for hydrocarbons. For overpressures to exist, the right set of conditions needs to occur in the right order and timeframe. Just like a hydrocarbon play, overpressures need a source (generation mechanism), reservoir (the overpressured formation) and seal (ability to maintain overpressures over geological time). Current pore prediction methods do not consider overpressure over the geological timespan of a basin, and commonly result in overpressures being encountered in unexpected formations and depths, or at greater magnitude than anticipated, and has resulted in many drilling incidents.

Play-based pore pressure prediction involves undertaking pore pressure analysis in a similar holistic manner to how prospects are generated during hydrocarbon exploration. The process involves using basinscale geology to establish likely overpressure mechanisms and formations (akin to identifying sources, reservoirs and seals); determining timing of overpressure generation throughout burial history, and; identifying major events causing overpressure transfer or dissipation (akin to hydrocarbon generation, charge analysis and trap development). Regional concepts are used to develop models to determine the likely locations and magnitude of overpressure (akin to hydrocarbon fairways and plays). Finally, regional learning's are applied at the prospect scale to select the best methods to predict pressures for planned wells. The innovation, and added benefit, of this new and novel approach is that ‘play-based pore pressure prediction’ can also be used to identify successful new exploration plays. Herein, I present an example of ‘play based pore pressure prediction’ from the Malay Basin that was used to improve drilling safety, and developed a new play concept that has subsequently resulted in 3 successful discoveries.
Design and Installation of Coupled Mooring System for Tender-Assisted Drilling at a Deepwater TLP
Authors: Kota Ravikiran , Yip Kenneth , Jamal S Amurol
Published: March 2018

The first Tension Leg Platform (TLP) in Malaysian waters was installed in 2016 at a water depth of about 500 m. It is notable in being the 2nd deep water platform in Malaysia with tender-assisted drilling (TAD) feature. The semisubmersible TAD vessel was connected to the platform using nylon hawser ropes which together with chain-polyester-wire moorings on the TAD and TLP allow for station-keeping during drilling operations. This paper describes the planning and execution of the mooring installation campaign. The paper also brings up key learnings from the campaign that may be useful to consider for risk reduction in future projects of similar nature.

Mooring system was purpose-designed for the TAD vessel with ground chain and polyester segments connecting to rig wire for each of its 8 mooring lines. Installation plan was based on pre-installing suction piles and pre-laying ground-chain and polyester. These pre-laid moorings were then retrieved for hook up to the TAD at site. One of the major challenges was identifying suitable pre-lay routes for the lines due to widely prevalent geo-hazards and exclusion zones on the seafloor. Close attention was also given to installation methods of hawsers between the TLP and TAD with emphasis on minimizing personnel exposure to risks of working under tensioned lines and over water. The installation campaign involved several vessels in the field simultaneously operating in the field and was closely coordinated with efficient SIMOPS plan and execution.

Early engagement with various disciplines and stakeholders is crucial in minimizing risks. Interfaces with engineering contractors, geomatics and geotechnical teams, component suppliers and installation contractors were instrumental in safe and injury-free installation and hook-up campaign of the TLP-TAD system currently under operation.

One question that is brought up is to do with risks versus values of load-testing synthetic mooring lines in field. While the need for such tests is well known, operational and safety risks require close attention.
Mitigating Wellbore Stability Challenges of Extended-Reach Drilling in Overpressure and Naturally Fractured Formations
Authors: Asadi M. S. , Rahman K. , Ta Q. D. , Ha V. , Phuong H.
Published: March 2018

When building a 1D geomechanical model for the Rang Dong field in Cuulong basin, offshore Vietnam, the rock structure was found to be very complex. In addition to inter-bedded shale and sand sequences in the overburden, there is an overpressured stratum immediately below and above the normally-pressured and highly fractured sandstones and volcanic rocks at the target depth. During the drilling of offset wells, multiple tight spots were experienced in the overburden. An inflow was detected in the volcanic rocks, and consequently the mud weight was increased in the deeper section of overpressured zone. Further, severe mud losses occurred in the underlying normally-pressured and highly fractured sandstones, and eventually stuck pipe was experienced. This study shows the development of a field-wide geomechanical model that is able to match all the drilling experiences in the offset wells.

A geomechanical model was developed for the field in which in-situ stresses and rock mechanical properties were calibrated with field data and lab measurements. The model predicted different types of borehole failures such as breakouts and drilling-induced fractures that contributed to different types of wellbore instability events in existing wells. Analysis showed that drilling with a significantly high overbalance pressure in the fractured zone increased the risk of tool string differential sticking and stuck pipe. To investigate the root causes of dynamic mud losses in the fractured intervals with major intersecting faults, a Mohr-Coulomb friction sliding criterion was applied. The analysis showed that the majority of natural fractures and faults, which are oriented in the north-east and south-west (NE-SW) direction, are critically stressed and may become conduits for drilling fluid and cause mud losses.

The geomechanical model was used to design a mud weight program for an upcoming well. This program was optimized to mitigate the issues experienced during drilling of the offset wells. The results of this study led to an optimized mud program to minimize shale breakouts in the overburden, control the risk of kicks in the overpressured zone, and reduce the risk of mud losses in the fractured formation. Additionally, an optimized casing program and the use of lower mud weight were recommended, with the addition of loss circulation material (LCM), to drill a highly deviated wellbore within the fractured formation. The drilling campaign of the planned well was successful with good drilling practices such as equivalent circulating density (ECD) control, good hole cleaning and use of the recommended mud weight programs and optimised drilling fluids suggested by this study.
Antinode Fairings: An Optimum Solution for Reduction of Vortex Induced Vibration
Authors: Ramadasan S. , Tao L. , Dev A.
Published: March 2018

An excellent vortex suppression device, in the form of an antinode fairing is presented towards reducing the Vortex Induced Vibration of structural members exposed to flow. An analytical procedure is also developed to optimise the depth and location of the fairings along the members. Two newly developed fairing sections are tested on cylindrical legs of a Jackup model and the results are qualitatively compared with the expected behaviour, particularly the effect of selected fairlead depth and location. A simplified mathematical model is developed based on the principle of conservation of energy, which could be used to decide the optimum location and depth of the vortex suppression devices for the cylinders undergoing Vortex Induced Vibration in a uniform flow. Based on the mathematical studies, modal antinodes are found as the optimum locations for the installation of the fairings and accordingly two compact leg fairing designs have been developed for practical applications. Those are based on NACA0018 profiles but with reduced L/B ratios of around 2.40 and 3.00. The tests with scaled down Jackup models with cylindrical legs demonstrated that both the fairing designs could reduce Vortex Induced Vibration amplitudes significantly, by around 80%. The weathervaning stability of both the fairing designs were also found to be satisfactory. From the mathematical studies and test results, it is inferred that fairings contribute to the reduction of Vortex Induced Vibration in three ways; reduction of excitation force, disruption of vortex synchronisation and the increase in fluid damping. Fairings are also found not to have significant bearing on the drag coefficient of the structure. The fairing design with the lesser L/B ratio of 2.40 is found to be an optimal solution for vortex suppression, when the structure is not sensitive to drag forces. However, fairings are found to initiate galloping responses at higher flow speeds above the lock-in range and hence it is recommended that the same shall be of the detachable type for cylinders exposed to large flow speed variations. The mathematical approach presented will enable practicing engineers to design and optimise antinode fairings for structures experiencing Vortex Induced Vibration. The two fairing section offsets presented may be readily used by Industry for practical applications.
History Matching and Uncertainty Assessment by Using the Ensemble Kalman Filter
Authors: Xu Zhongyi , Cheng Linsong , Wu Yonghui , Huang Pin JiaandShijun , Fang Sidong , Hao Junlan , Gao Yinshan
Published: March 2018

Accurate assessment of uncertainty of production performance is critical for successful planning and assets development. Particularly in deepwater scenarios, where the uncertainty in the fluid and reservoir characterization is of high level for the difficulties for well testing, fluid and core sampling. Therefore, specific methods are needed for efficient uncertainty quantification of production for deepwater reservoirs with limited information.

In this paper, we introduce a history matching method to assimilate static geological data and production data base on the ensemble Kalman filter (EnKF). The EnKF is independent of simulators, and is suitable for uncertainty assessment, reservoir monitoring and performance prediction. We tested this method with a deepwater case. We analyzed the effects of initial ensembles and production history. After that, the uncertainty of production prediction is quantified and the posterior distribution of cumulative production can be estimated.

The EnKF is shown to be efficient in updating fluid and reservoir heterogeneity. By sequentially assimilating observed data, the EnKF is suitable for reservoir monitoring and performance prediction. The results indicate that history match with plausible geology can be improved with the improvement in the generation of the initial ensemble. History matching with longer history can narrow the range of ultimate recovery distribution, thus the uncertainty can be decreased. And the results also show that the updated amounts of parameters in the ensemble is larger in the first iteration, and it will get smaller gradually with more data been assimilated. After the history matching, the ultimate recovery can be obtained with each set of parameters in the ensemble, the uncertainty can be quantified with the statistical frequency distribution of recovery.

The proposed methodology provides a practical means to assess uncertainty in history matching for deepwater fields. This method can also be used to project and risk management.
Returning to Play-Based Exploration; Exploring the Fundamentals
Authors: Shoup R. C.
Published: March 2018

Many companies are now re-focusing on play-based exploration, representing a return to our pre-1990s geoscience roots. Play-based exploration involves understanding all elements of the petroleum system for a given basin or play and then examining how, and more importantly where, those elements come together. This paper will examine the fundamental methods using examples across Asia and review step by step procedures of the play-based exploration process.
Validation Process of IWEX 3D Ultrasonic Imaging for Girth Weld Inspection
Authors: Pörtzgen Niels , Ent Jan van der , Brisac Gaspard , Solem Ola , Pinier Ludovic , Steinskog Bjarne
Published: March 2018

IWEX is an innovative ultrasonic testing inspection methodology which went through a complete qualification program for Carbon Steel pipeline girth weld inspection, from DNV OS F101 certification to implementation on a pilot project, with the aim to be widely implemented into the market as the repair rate and schedule of a project could be drastically reduced. The qualification process will be detailed, with particular focus on feedback from the first production project.

IWEX is a novel inspection philosophy based on ultrasonic imaging of full matrix capture data. Indications in girth welds are imaged real time in 2D and 3D. The images reveal the presence of indications whereby the orientation, position, height, etc., are displayed in true context to the weld geometry. Identification and sizing of indication can be done accurately and unambiguously, leading to a reduced repair rate. Because the IWEX images are independent of the weld bevel design, a standardized sensitivity block can be used, whereby the work preparation and the number of calibration blocks are reduced significantly.

In order to benefit from the full potential of the IWEX technology, industry acceptance is required. Therefore, IWEX was subjected to an extensive qualification program according to DNV OS F101 for carbon steel applications. When the DNV qualification program was completed successfully, the IWEX technology was applied in parallel to a standard AUT inspection on an actual project production line, where a significant number of welds are fabricated every day. This was to ensure the robustness of the system (software and hardware) in a production environment details of which have been published already [1]. The final step in this technology qualification process was the standalone use of the IWEX system on a full scale pipeline project, consisting of two carbon steel pipelines of 16" and 10" diameter. Direct feedback from the Contractor spool base fabrication team on the IWEX performance has been gathered in detail and used to identify required improvements on software and hardware for full project fitness. Feedback from the pipeline owner is also included. This will be detailed in the paper.

This paper describes the IWEX qualification process and details the validation approach and feedback obtained during the use of the IWEX system on its first commercial pipeline girth weld project. It also details all advantages of IWEX technology compared to the standard AUT inspection technique which has been in use until now.
Holistic Approach for the Design of Drill-In Fluid
Authors: Rincon Marco , Phillips David , Gupta Sanjeev , Jacobs Stephen
Published: March 2018

Drilling wells in mature fields normally entails the integration of multidisciplinary teams to increase the likelihood of a successful drilling and completion program. Maximizing wellbore productivity requires thoughtful planning involving analysis, studies, and risk assessment of the best alternative solutions for well drilling and completion.

Selecting reservoir drilling and completion fluid to minimize rock formation damage requires a high level of consideration. Selecting an appropriate fluid strategy becomes more significant when the reservoir section involves horizontal drilling and an openhole completion design. This paper details the design criteria and final application of a nondamaging drill-in fluid to drill a horizontal well completed as open hole in a mature field (first of its kind in the field).

The fluid design strategy was driven based on analysis of reservoir rock samples, reservoir fluid chemistry analysis, and the natural permeability of selected core samples. The fluid selected was a monovalent brine system using highly clarified and acid-soluble biopolymers as filtrate reducer and viscosity control, respectively, and an engineered and tested bridging package based on sized calcium carbonate. The fluid also contained an amphoteric amine to control clay swelling and dispersion. The nature of the well completion used an in-situ acid-generating filter-cake breaker system for removal of filter cake and damage encountered during reservoir drilling or completion. The filter-cake breaker system also affected fluid design (e.g., compatibility between the two systems), which was incorporated into the design strategy. Additionally, the nature of certain details of the completion architecture affected the breaker system application and was necessary to redesign the filter-cake breaker system to achieve optimal wellbore cleanup while accommodating constraints in the completion design and operation.

Finally, application of the fluid program used with the drilling and completion design and architecture rendered a successful project resulting in higher than expected hydrocarbon output.
Egina Deep Water Development: Isolation Barrier Valve Case Study
Authors: Forrest G. , Morand C. , Johnson K. , Okengwu V. , Chaloupka V.
Published: March 2018

A major operator manages multiple deep water projects in the Gulf of Guinea. This paper describes the latest 44-well project in Nigeria. The operator required an ISO 28781 qualified bi-directional subsurface isolation barrier valve (IBV) (Fig. 1) to be installed in each well. This work presents results of IBV deployment in the field.

The wells were drilled and completed from sixth generation drillships. To comply with the operator's dual barrier policy, a bi-directional IBV was installed in each well to help ensure reservoir isolation for temporary well suspension or before running upper completion and tree installation. Careful attention to well fluid cleanliness, sound quality assurance/quality control (QA/QC), and operational procedures were considered paramount to successful remote opening of the IBVs and were identified as best practices by both parties.

The IBV is run in the open position as an integral part of the lower completion. A collet shifting tool closes the ball isolating the formation, enabling inflow and positive pressure testing to be performed. The reservoirs are isolated by the closed ball in the IBV, allowing safe installation of the upper completion from a floating rig or well suspension without a subsea tree. The use of an ISO 28781 Type CC V1 qualified IBV provides both zonal isolation and fluid-loss control. Once a well is completed and the subsea tree installed, the IBV is remotely functioned to the open position by applying multiple tubing pressure cycles.

The first batch of wells were drilled and completed with lower completions and suspended while waiting for subsea tree deliveries. Later, wells were drilled and completed with both lower and upper completions, and trees installed later from an offshore inspection maintenance and repair (OIMR) vessel. IBVs were successfully closed and inflow and pressure tested during the lower completion phase.

IBVs are run in sieved non-aqueous based mud (NABM). Filtered high viscosity pills are spotted across the IBV before closing. Once closed, the casing above the IBV is displaced to filtered completion brine at a rate ensuring any debris is lifted to the surface. The wells remain suspended with IBVs closed until the operator performs flowback and injectivity testing from a drillship. Additional injectivity testing was also performed from an OIMR vessel. Well suspension duration with IBVs closed varied between two months and 2.5 years. All valves cycled opened without issues. Four coiled tubing (CT) interventions were performed in the field, passing through the open ball without issue, confirming the IBVs were in the fully open position.

This paper describes full QA/QC and operational procedures, which led to successful deployment and excellent functionality of the IBVs.
Fracture Characterisation Through Image Log Conductive Feature Extraction
Authors: Xian Hong , Tueckmantel Christian , Giorgioni Maurizio , Wei Lingli , Lai Chee-Pan
Published: March 2018

An approach is presented for fracture porosity, fracture aperture and permeability evaluation through extracting conductive image features from FMITM borehole image logs.

The methodology of image feature and in particular fracture recognition, extraction and characterisation is based on the borehole image tool button response simulation model originally developed by Luthi (1990) for the water-based mud system and the principle of 2D fracture intensity (P32) to 3D fracture intensity/volume (P33) transformation. The extracted conductive image features allow us to distinguish open fractures and karst features. Fracture aperture is calculated as a function of the button resistivity, tool current & voltage, mud resistivity and background rock resistivity. Fracture porosity is computed with consideration of fracture type, well type and condition. Fracture permeability is estimated by taking fracture aperture, type and intensity into account.

The results for naturally fractured tight carbonate reservoirs are demonstrated. Various types of conductive features are successfully recognised and characterised using the new approach. Sedimentary features like bedding and shale boundaries are identified too. Drilling induced or borehole breakout features have been distinguished and excluded from true nature formation features. The robustness of the fracture characterisation can be demonstrated through various field examples and reservoir model implementation.

The new approach provided independent fracture characterisation inputs for discrete fracture network (DFN) and dynamic models of the fractured reservoir examples shown.
Additive Manufacturing Metal 3D Printing for the Marine and Offshore Sector - Paving the Path from Lab into the Field
Authors: Wistance William , Lee Jeremy
Published: March 2018

Additive manufacturing has been heralded as a revolutionary process set to change the face of manufacturing forever. However, after all the hype dies down, the reality is that taking this technology from the laboratory and applying it to real world applications in the field can be more challenging than some news reports might lead to people to believe. The idea of a plug and play machine is still a way off, although it will one day become a reality.

This paper highlights some of the challenges facing the marine and offshore industry's adoption of the technology, how these challenges can be overcome and the potential benefits that this technology can yield. Based on the experiences of working with manufacturers and end users that have utilized this technology to manufacture products to meet demanding industry requirements, this paper will show that the technology can be adopted safely. There is a need to improve quality control, production consistency and further develop the complete supply chain. The development of international standards and the greater adoption of independent certification are ways to give confidence to the offshore industry to adopt this technology. Although there are challenges to overcome, the potential benefits can be substantial, both technically and economically.
Revealing Uncertainty and Maximizing Mature Field Production—A Novel Approach to Addressing Well Conformance Issues/Well Integrity Evaluation: Case Study from Offshore Sarawak, Malaysia
Authors: Parashar Sarvagya , Goenawan Fransiska , Jagannathan Srinivasan , Lee Chung Yee , Iyer M. S. , Wu Ivan Zhia Ming , Aggarwal Gaurav , Amin M. Farid B. M. , Juan Saw Li , Hui Nicholas Foo Kwang , Wei Gan Teik , Ismail W. Rokiah , Razman Nur Faradilla M.
Published: March 2018

This paper introduces and evaluates a next-generation acoustic conformance-monitoring system that helps identify the depth and accurate radial location of undesirable leaks in a well. Determining the leak's flow pattern in and around the wellbore is also used to understand activity within the surrounding wellbore region.

The acoustic conformance tool was run employing a memory slickline operation in a well located offshore Sarawak, Malaysia. The tool successfully acquired both low- and high-fidelity data, which were subsequently used for leak characterization analysis. Using an array of acoustic sensors, the tool is capable of detecting undesirable flow throughout the well structure. The vertical accuracy is within inches and estimates the radial location around the wellbore. Before the operation, careful and thorough prejob design is necessary for data acquisition to help reduce uncertainty in post-interpretation. These include detailed operational sequences in terms of leak stimulation of various annuli in the well to obtain optimum results. Subsequently, the signals are analyzed using a beam-forming method to identify leak distances and a flow map to further understand flow characteristics.

The study well is a gas producer completed with a 7-in. single string. Post-data processing and interpretation revealed a continuous high-frequency noise spectrum from the bottom of the logging interval to the surface, indicating gas movement, which was further confirmed by two-dimensional (2D) flow map analysis. Results indicated gas movement in Annuli C and B. Based on results, production logging sensors, and well completion statuses, inferences were made regarding this gas movement and its possible sources—a cement window in Annulus C and cement channel in Annulus B.

This technology accurately identifies and pinpoints leak sources, assisting the asset owner with planning and designing remedial work to help reduce undesirable fluid, which benefits total production.
Prediction of Hydrate Phase Equilibrium Conditions for Different Gas Mixtures
Authors: Sadeq Dhifaf , Iglauer Stefan , Lebedev Maxim , Barifcani Ahmed
Published: March 2018

Gas hydrate formation poses a significant threat to the production, processing, and transportation of natural gas. Accurate predictions of gas hydrate equilibrium conditions are essential for designing the gas production systems at safe operating conditions and mitigating the problems caused by hydrates formation. A new hydrate correlation for predicting gas hydrate equilibrium conditions was obtained for different gas mixtures containing methane, nitrogen and carbon dioxide. The new correlation is proposed for a pressure range of 1.7-330 MPa, a temperature range of 273-320 K, and for gas mixtures with specific gravity range of 0.553 to 1. The nonlinear regression technique was applied to develop the correlation based on 142 experimental data points collected from literature, validated with 85 data points not used for developing the correlation. The statistical parameters analysis showed an average absolute error (AAPE) of 0.2183, a squared correlation coefficient (R2) of 0.9978 and standard deviation (SD) of 0.2483. In addition, comparing the new correlation results with the experimental data and with those calculated by other correlations show an excellent performance for the investigated range.
From Compliance To Commitment: The Impact of Human Psychology on Safety Culture
Authors: Mahmood Sadaqat , Mahmood Kashif , Abdullah Muhammad
Published: March 2018

Surrounded with life threatning hazards, establishing the safety culture in its true spirit is extremely important for oil companies. The lessons from past require us to make no compromise on this. A good safety culture provides clear guidelines to the employees, is accepted by all, addresses all issues and concerns, has proper monitoring systems and is just in its implementation. To establish this, employee conformity stands as the biggest challenge as no program can be applied if not accepted by the employees. This acceptance of any change is what we categorize as commitment to comply; where employees have inner motivation to comply with safety guidelines and programs. In this paper we have tried to explore the same. In view of available literature, we developed two separate questionnaires for employees and HSE professionals. The results clearly demonstrate that employees want to know why a safety program is being implemented and efficiency of any program relies on inner motivation of the employees. Based on same we have presented our self regulation model that helps in the success of any safety program.
An Innovative, Low Cost Solution for Sampling in Highly Deviated Wells
Authors: Aryusanil Thanawat , Rakela Tribor , Azevedo Marcelo , Costam Yosef Ronald , Fadjarijanto Ari
Published: March 2018

Sampling in a highly deviated well involves additional risks that can compromise efficiency and costs. Operators and service companies have developed options to overcome the technical challenge of going from tubing-assisted logging to tractor-conveyed operations.

Tubing-assisted logging will mitigate the issues and stuck risks caused by wireline key seating, differential sticking, swelling formations, heavy muds, borehole breakout, doglegs, ledges, and cuttings but will require slower operations resulting in additional rig time and therefore costs. Tractor conveyance, on the contrary, can be efficient but will add costly operating rates and higher cost exposure if the tools are lost in hole.

An operator in offshore Southeast Asia had an objective to perform formation evaluation by means of pressure tests with pump out to obtain clean samples for CO2-level measurements in a slim well geometry (6 1/8-in. hole) with 73° deviation. Sampling wheels that configure with the wireline formation tester tool were introduced to the operator to reduce the contact area, keep the tool body off the low side of the borehole wall, and aid gravity descent.

The operation objective was successfully accomplished and reached the target depth (TD)/reservoirs by performing five pressure tests, setting up three fluid characterization stations, and retrieving six samples in approximately 12.5 operating hours, resulting in savings of more than USD 350,000 for the operator.