bluuebunny/crossref_metadata_2025 huggingface dataset:
Using Multilaterals to Extend Well Life and Increase Reserves: Case History of an Offshore Thailand Project
Authors: Hogg C. , Cham S. , Hicks C. L.
Published: March 2016

This paper will detail a recent four-well TAML Level 4 multilateral (ML) installation in a field located offshore Thailand. The drivers that led the operator to seek out a first time multilateral solution for this field development will be covered, along with the variables considered in selecting the specific multilateral system that was ultimately chosen. Both the difficulties encountered and the successes achieved during the multilateral planning, installation and perforating processes will be covered.

Although ultimately successful in all four wells, the multilateral construction process was not without challenges. The shallow depths of the multilateral junctions and the resulting weak formations resulted in a need for maximum mechanical support at the junction. At the same time, the multilateral needed to use a minimum of specialized equipment and processes to meet the timing urgency resulting from the existing rig availability deadline. This short timing made equipment and personnel sourcing a vital factor in the eventual success of the project. The importation of the perforating charges that are used in this ML system was especially challenging and must be taken into greater consideration when planning future installations.

At the end of the project, the success of the installations was due in large part to the simplicity and reliability of the ML systems used, but another key factor in the success was the necessary and careful coordination of planning and activities between the operator and the service company providers involved in the multilateral construction process. The historical perception in the petroleum industry has often assumed that multilaterals require extensive lead times and that operating companies without previous multilateral experience face a steep learning curve to achieve successful results. The success of this project, however, demonstrates that today's multilaterals can be reliable and simple enough to consider even when time requirements are tight and in areas where multilaterals are considered a "newer" technology.
An EOS-Based Dynamic Modelling for Depressurisation of Pressure Vessels Containing Hydrocarbons
Authors: Jin Ryu Si , Ko Yoonae , Lim Youngsub
Published: March 2016

Managing overpressure of a pressure vessel is critical to the safety of a hydrocarbon producing facility. As a result of rapid depressurisation called blowdown, temperature of the pressure vessel wall can be severely decreased. For these reasons, dynamic behavior of properties (e.g., temperature in pressure vessels) during depressurisation has to be analyzed for material selection and design process. In this work, a dynamic model for depressurisation was developed to simulate the low temperature phenomena inside a pressure vessel under depressurzation. Thermodynamic and transport property calculation theories were used to describe hydrocarbon systems. Heat tranfers between internal fluid and inner wall surface and between surroundings and outer vessel wall surfaces were considered. Temperature of each vessel wall surface was calculated using transient conduction temperature profile. The result showed good fitting to reported experimental data.
Novel Methodology to Estimate Reservoir Pressure and Productivity Index in Unconventional and Conventional Reservoirs Using Production Data
Authors: Poe Bobby , Varma Gottumukkala
Published: March 2016

Evaluation of the initial reservoir pore pressure, the current average prevailing reservoir pressure, and the deliverability of a well commonly results in the need for one or more pressure or rate-transient tests of a well's performance to be conducted in order to properly characterize the properties of the reservoir and the well completion efficiency. Conventional pressure build up or multi-rate drawdown tests have commonly been used for this purpose. These types of transient tests can last for days or even months in low-permeability unconventional reservoirs, resulting in prohibitive production deferments and operational expenditure. The reservoir pressure and the well deliverability are key indices that are used to properly characterize the reservoir properties and the expected ultimate recovery of a well.

This paper presents the development and application of an elegant production performance analysis technique that can be used to accurately determine the initial and/or average prevailing reservoir pressure of both conventional and unconventional reservoirs (for any permeability level), for wells of any type, time level, inner and outer boundary condition and flow regime, using only transient well production data (flow rates and bottom hole flowing pressures as a function of time). With the improvements in accuracy that can now be achieved in determining the average reservoir pressure, reliable and accurate transient Productivity Index values can be obtained for producing wells.

In addition to the improvement in determining the initial/average reservoir pressure, the newly developed production analysis procedure also provides an excellent means of Quality Control for the validity and consistency in the reported well flow rates as a function of the system drawdown. Examples are presented in this paper in which a variety of different flow rate measurement or estimation techniques have been utilized. These include a state-of-the-art advanced and extremely accurate surface multiphase flow rate metering system, flow rates computed from downhole flow control valve measurements, as well as an example in which well flow rates have been estimated using measurements obtained for monitoring the performance of an electrical submersible pump.

The acquisition of extremely accurate, high-frequency production performance data greatly enhances the evaluation of the reservoir pressure obtained with the analysis technique presented in this paper. Temporal measurements of the sandface flowing pressures and flow rates, obtained for a time scale on the order of minutes or hours is often adequate for accurately determining the initial or current average reservoir pressure. However, the use of high-frequency production data obtained with permanent downhole gauges and surface (or downhole) continuous flow rate metering systems offer even greater precision in evaluating the reservoir pressure with this analysis.
Distribution of Surface Elevations in Nonlinear Seas
Authors: Tayfun M. A. , Alkhalidi M. A.
Published: March 2016

The statistical distribution describing nonlinear narrowband waves characterized with second-order nonlinearities is simplified to an explicit closed form amenable to theoretical and practical applications. The approximate form and its salient features are examined and compared with oceanic measurements in deep and shallower water depths. The approximate form developed here provides certain advantages in terms its algebraic simplicity, accuracy and a somewhat wider domain of validity, in particular, relative to a previous approximation derived from the same second-order narrowband model. Comparisons with the oceanic measurements in deep and shallow water depths also yield good agreement with the approximate form over the range of surface elevations where the second-order theory provides a relatively valid representation of nonlinear waves.
Inclined Pull-Out Capacity of Dynamically Installed Anchors in Clay
Authors: Chen Zongrui , Sun Jie , Gu Hai
Published: March 2016

Dynamically Installed Anchors (DIAs) refer to anchors which can embed themselves by free-fall from a specified height above the seabed. They have been widely regarded as the most promising deepwater anchor concept in terms of several advantages over other anchors. First, it is economical because of ease fabrication, quick installation, and no requirement from external source of energy. Second, the installation cost is less depend on the water depth. Finally, the holding capacity is less sensitive to the soil undrained shear strength profile since higher seabed soil shear strength permit less penetration depths and vice versa. However, a degree of uncertainty still exists in relation to predicting the embedment depth and subsequent pull-out capacity especially the inclined pull-out capacity.

The pull-out capacity of DIAs can be dominated by the vertical or horizontal failure mechanisms or a combination of the two. When the combination controls, the DIAs are referred to as being under the inclined pull-out failure. This paper focuses on the inclined pull-out failure of DIAs. A series of finite element analysis on pull-out resistance of DIAs in normally consolidated clay was carried out. First, the numerical results were validated through experimental results and analytical empirical results. A proper method to model the inclined pull-out of DIA is illustrated. Then, a methodology for evaluating the inclined pull-out capacity of DIA is proposed based on the numerical parametric study. This method is capable of predicting pull-out capacity of DIA for various embedment depths and DIA aspect ratios. Finally, the design procedure for DIA is proposed.
Development of a Novel Hybrid AUV System for Pipeline Inspection in Gulf of Thailand
Authors: Hoonsuwan Phakhachon , Tipsuwan Yodyium , Slanvetpan Thana
Published: March 2016

Oil and gas companies are increasingly being forced to conduct their sub-sea pipeline inspections in increasingly more hostile and deeper waters. Typically, Remotely Operated Vehicles (ROV) are used for sub-sea pipeline inspections and these are controlled by experienced ROV operators from a surface support vessel, which tend to make ROV operations costly. Conversely, an Autonomous Underwater Vehicle (AUV) can perform sub-sea pipeline inspections without the need for a human operator. This paper sets-out to describe the development of a novel Hybrid AUV (HAUV) system, composed of two unmanned vehicles and designed specifically for sub-sea pipeline inspection. The first vehicle is a compact Unmanned Surface Vehicle (USV), which tracks a sub-sea pipeline from the sea surface. The second vehicle is a HAUV, which is connected to the USV via a fibre optic tether. Both vehicles operate together to automatically inspect sub-sea pipelines. The complete system is controlled by a remote control station on the surface. At this early stage of development, its capability is limited due to its size and battery power source but lab-scale units have been developed and have undergone field testing. Our team study is ongoing and endeavours to refine the HAUV system-capabilities enabling us to offer a cost-effective approach for sub-sea pipeline inspection in the near future.
Centrifuge Model Study on Inclined Pullout Behavior of Square Plate Anchors in Normally Consolidated Clay
Authors: Chen J. , Leung C. F. , Chow Y. K.
Published: March 2016

The inclined pull-out behavior of square plate anchors embedded in normally consolidated clay is presented in this paper. A series of centrifuge model tests have been performed to simulate plate anchor extraction process. Clay sample was prepared under self-weight during centrifuge spinning, where soil undrained shear strength increases linearly with depth, simulating the typical soil strength profile in offshore environment. Pre-embedded plate anchor was pulled out with displacement and resistance measured. Anchor capacity is quantified and presented in the form of capacity factor. The effect of anchor embedment ratio (the ratio of embedment depth to anchor width) and pullout inclination on capacity factor is investigated.
Advances in Computational Hydrodynamics Applied to Wave-in-Deck
Authors: Chen Yu , Wu Yanling , Bahuguni Anand , Gullman-Strand Johan , Zhang Yali , Stewart Graham , Lv Xin
Published: March 2016

In this study, advanced numerical CFD tools based on OpenFOAM are developed to generate extreme waves for the investigation of wave-in-deck loads on fixed offshore structures. The numerical method employs a Navier-Stokes solver with the free-surface captured by the volume of fluid (VOF) approach. The advantages of numerical simulation through CFD are: 1) full scale simulation of nonlinear phenomena; 2) potentially more accurate prediction as viscous and inertia forces are included whereas a model test based on Froude scaling can only scale the inertia forces; and 3) detailed insight into the flow and resulting loads. The numerical simulations for long-crested extreme waves capture the evolution of impact loads and free surface during the interaction with the platform deck. CFD provides more accurate results than analytical tools and the flow physics can be studied in detail, providing further insight that can lead to improvements in the analytical tools. This study also provides a benchmark set of problems for wave loading on platform decks.
Limitations of Using Smart Wells to Achieve Waterflood Conformance in Stacked Heterogeneous Reservoirs: Case Study from Piltun Field
Authors: Khural Harsimran , Rai Udai Bhan , Kumar Ram , Marpaung Billman , Faulkner Andrew , Kumar Rajan
Published: March 2016

The use of smart completion with downhole fluid control through Inflow Control Valves (ICVs) has been extensively described in the literature for balancing the water injection profile and improving the sweep efficiency in commingled water injection. This paper describes the limitations of such a system in ensuring zonal distribution of water in stacked, highly heterogeneous reservoir systems.

Voidage replacement and pressure maintenance requirements necessitate waterflood under fracturing conditions in the four stacked reservoirs (Zone 1 to Zone 4) in Piltun field, offshore Sakhalin Island, Russia. These reservoirs are heterogeneous with differences in their permeability and fracture gradient. Consequently, smart injectors with four ICVs were planned to maintain the desired injection allocation in these reservoirs. The initial injectivity of these wells was extremely low with all of the injected water going to the deepest zone (Zone 4). An expensive pump upgrade improved the overall injectivity, with drastic changes in the distribution of the injected water amongst the reservoir layers. Contrary to performance prior to pump upgrade, the shallowest zone (Zone 1) emerged as the dominant receiver of injected water. Overall, the zonal distribution of water remained a problem with little success in injecting water in the remaining two zones (Zone 2 and Zone 3). Very limited improvement in the water distribution was obtained by manipulating the ICV valves.

Sector modeling was taken up for the injection wells to understand the injection behavior. Modelling results show that after the pump upgrade, fracturing was initially achieved in all zones, although sustained fracture opening and propagation was only possible in Zone 1, the reservoir with better flow properties and reasonably low fracture gradient. The other zones gradually reverted back to injection under matrix conditions with time. The additional pressure drop created by the flow control device is not sufficient to choke back the major zones and achieve sustained fracture growth and water injection in the minor zones in Piltun field. The results demonstrate that the use of intelligent completion for waterflood conformance can be limited by large stress and permeability contrast.
Mitigation of Pig-induced Slugs by Combination of By-pass Pig and Inlet Separator Dual Control Valves
Authors: Park Sangmin , Kim Minseong , Nydal Ole Jørgen , Lee In-Beum
Published: March 2016

For the determination of the design basis of the inlet separator in the offshore oil and gas plant, one of the most crucial factors is the liquid surge volume generated mainly by the transient phenomena such as riser slugging and pig-induced slugging. In particular, pig-induced slugging frequently brings about the most serious slug problems. In the study, a combination of a by-pass pig and an inlet- separator dual control valve scheme is introduced for the application, of which pigging operation is not possible by a conventional method because it causes inlet separator flooding. First, for the purpose of the estimation of the simulation accuracy, the stability map generated from an S-shaped riser experiment is compared with the prediction of OLGA simulation. And then, it is demonstrated that a combination of a by-pass pig and and inlet separator dual control scheme makes it possible to operate stable pigging, even though a conventional pigging is not available due to the excessive pig-induced slugging.
Actively Managing Hydrates Without Compromising on Production and Safety Will Reduce OPEX
Authors: Ahmed S. , Azhar M. A. , Hagag A. M. , Torky A. N.
Published: March 2016

Hydrates have been a constant threat to subsea deepwater operations since pipelines were first used to transport multiphase fluids. Hydrate blockages in pipelines and processing equipment can cause deferment of production and as a result can cause millions of dollars in losses.

The extensiveness and complexities of subsea production systems and deepwater developments such as West Delta Deep Marine (WDDM) in Egypt pose huge challenges in implementing hydrate management strategies. In the past, unplanned strategies were implemented in WDDM due to a lack of Flow Assurance (FA) awareness and understanding, resulting in production deferment caused by hydrate formation or blockages. Operational Expenditures (OPEX) on hydrate inhibitors such as Mono Ethylene Glycol (MEG) and Methanol (MeOH) have been increasing significantly.

Since the implementation of Flow Assurance in WDDM, work has focused on key areas of the development that were hydrate prone, by making use of in-house software and industry good practice. A holistic view of WDDM including equipment and instrumentation was taken, along with the chemistry behind why hydrates form.

To minimise the deferment to production, hydrate monitoring, previously based on a single pressure reading in the flowline, was challenged and changed to the current technique which is based on flowline pressure drop across multiple elements such as flowline, infield line and valves. This has been made possible by implementing a monitoring system based on Pi linked to the control room, allowing engineers throughout the organisation to review a wide range of actual data in real time. As a result of continuous monitoring and optimisation, hydrates are no longer seen as a threat to WDDM production.

Various achievements and lessons learnt in managing hydrates in WDDM over the past 12 years, specifically in hydrate prevention, monitoring, and remediation plan has been compiled. As a result, a "WDDM Hydrate Management Strategy" has been introduced for the operation and future development of WDDM. This paper will share the significant lessons accumulated in WDDM from actual experience of operating the field.
Nanofluids for Enhanced Oil Recovery Processes: Wettability Alteration Using Zirconium Oxide
Authors: Nwidee Lezorgia. N. , Al-Anssari Sarmad , Barifcani Ahmed , Sarmadivaleh Mohammad , Iglauer Stefan
Published: March 2016

Ultimate oil recovery and displacement efficiency at the pore-scale are controlled by the rock wettability thus there is a growing interest in the wetting behaviour of reservoir rocks as production from fractured oil-wet or mixed-wet limestone formations have remained a key challenge. Conventional waterflooding methods are inefficient in such formation due to poor spontaneous imbibition of water into the oil-wet rock capillaries. However, altering the wettability to water-wet could yield recovery of significant amounts of additional oil thus this study investigates the influence of nanoparticles on wettability alteration. The efficiency of various formulated zirconium-oxide (ZrO2) based nanofluids at different nanoparticle concentrations (0-0.05 wt. %) was assessed through contact angle measurements. Results from the experiments showed ZrO2 nanofluid have great potentials in changing oil-wet limestone towards strongly water-wet condition. The best performance was observed at 0.05wt% ZrO2 nanoparticle concentration which changed an originally strongly oil-wet (152°) calcite substrate towards a strongly water-wet (44°) state thus we conclude that ZrO2 is a good agent for enhanced oil recovery.
Sustainability Through the Use of Unmanned Aerial Vehicle for Aerial Plant Inspection
Authors: Kridsada L. , Chatchai La. , Manop C. , Thana S.
Published: March 2016

ROBOTS in Oil & Gas production! No, this is not science-fiction it is a reality. Robots have served in various industries for many years, but now the science of robots, or should we say "Robotics", is developing at such a rapid pace that robots have become far more diverse, infinitely smarter and are being used in ways that we would not have dreamt possible a few years ago, especially in the E&P and Petrochemical industries. In keeping with modern trends, PTTEP engineers have developed a multi-purpose Unmanned Aerial Vehicle (UAV), complete with "Plug and Play" imagery options, to perform a wide range of aerial monitoring and inspection applications. We call it a "Multipurpose Plant Inspection Octocopter" (MPIO). The MPIO project focuses on areas that are considered high-risk for human intervention and subsequently financially high-cost too. The MPIO has been designed and tested to perform various kinds of plant inspection; from offshore riser platform storage tank roofs to cooling tower observations, to name a few. But, in order to put the MPIO to the ultimate challenge and prove its viability, our engineers have been utilizing it to perform live flare-stack inspections, where radiated heat and turbulent air-conditions prevail.

To date, there have been many successful demonstrations providing quality high resolution pictures and proving the techniques applied. However, knowledge gained and ongoing development-effort will ultimately lead to the next step, a "Fully Automated MPIO" that will include; Auto Take-off, Auto Flight Control, Auto Landing, etc.
Vertical Cable Seismic (VCS) Survey for Buried Hydrothermal Sulfide Deposit
Authors: Asakawa Eiichi , Tara Kenji , Murakami Fumitoshi , Tsukaraha Hitoshi , Mizohata Shigeharu
Published: March 2016

In the Seafloor Massive Sulfide (SMS) exploration, the buried sulfide deposits without hydrothermal activity are important for mining development. We had proposed Vertical Cable Seismic (VCS) for exploration of SMS and found out it could reveal the buried deposit through surveys. The conventional VCS data processing gave us the large-scale 3D structure. We re-examined the data processing to focus on the very shallow part so that the detailed structure of the buried sulfide deposit could be recognized.

We adopted the Three-dimensional Pre-Stack Depth Migration (3D-PSDM) method that did not assume a horizontal structure since the hydrothermal area has a complex structure. In order to focus on the shallow part, we used a high-density gridded velocity model to achieve high accurate travel time calculation. Grid spacing is about one-tenth shorter than that of normal oil/gas exploration case. Velocity model is not complex but a two-layer model consisted of the seawater and sub-seafloor. The water velocity is adjusted to match the migrated ocean bottom reflection to ship-born multi-beam bathymetry.

The first VCS survey with GI-gun in 2011 and the second one with high-voltage sparker in 2013 in Izena Hole, Okinawa Trough, gave the high-resolution 3D PSDM volumes of 500m x 200m x 200m and 400m x 200m x 200m respectively. These results successfully delineated the top interfaces of the buried sulfide ore deposit that are consistent with the geological model provided by Japan Oil, Gas and Metals National Corporation (JOGMEC) using the core data of their intensive drilling. In addition, the existence of the high velocity zone was suggested beneath the seafloor by the estimation of velocity structure by Common Reflection Point (CRP) gather analysis. We consider the high velocity anomaly implies the existence of buried sulfide ore deposit.

These results suggest that VCS can reveal the distribution of buried sulfide ore deposits. We are developing a detailed velocity analysis method to reveal the velocity anomaly caused by the buried deposits. Furthermore, it is important to estimate other geophysical properties using EM, magnetic and gravity surveys. To confirm the distribution of the buried deposits represented by the VCS data, it is necessary to compare the VCS results and drilling cores by JOGMEC directly.
Pre-flush Design for Extended Scale Inhibitor Squeeze lifetime in Limestone Reservoir – Laboratory Investigations and Cost Benefit Analysis
Authors: Ghosh Bisweswar , Alklih Mohamad Yousef , Li Xin
Published: March 2016

Scale inhibitor (SI) squeeze treatment is an established practice in offshore fields to prevent inorganic scale deposition in the wellbore and near wellbore formation. Squeeze lifetime is measured by the duration for which the concentration of the chemical is released at a concentration above the required minimum inhibitor concentration (MIC). Hence, maximizing SI adsorption to the pore surfaces may proportionately enhance squeeze lifetime. However, most oil-field squeeze scale inhibitors being aqueous-based, it is unlikely to get optimum adsorption on an oil-wet formation due to unfavorable rock surface condition. This work is targeted towards optimum formation conditioning through an intelligently designed pre-flush treatment; so that the adsorption and lifetime of SI in an oil-wet carbonate reservoir are significantly improved.

Eco-friendly APG surfactants are evaluated with and without alkali and co-surfactants to design the pre-flush composition. A series of coreflood experiments are conducted in simulated reservoir conditions, using data and materials from a high temperature carbonate oil reservoir from the Middle-East. The results are evaluated in light of IFT and phase behavior and changes of rock wettability due to pre-flush treatment.

The results show that SI squeeze lifetime can be enhanced by as much as 240% when compared to conventional treatment and it has a direct correlation with wettability index and IFT. Anionic surfactant may look more attractive than nonionic surfactant due to favorable wettability alteration and highly reduced IFT, however they may not be the right choice for carbonate formation due to higher adsorption and competition with scale inhibitor molecules. Cost benefit analysis evince that introduction of the newly designed pre-flush treatment would results in improved economics through reduced treatment frequency, leading to minimized well intervention and consequent production loss.

Not enough attention is given on the design/optimization of pre-flush and conditioning of the formation to be used as adsorbent/storehouse of the inhibiting chemical in preferentially oil wet carbonate formations. The applicability of surfactant-alkaline has been long established as means of EOR mechanism but they are rarely investigated for near wellbore treatments to maximize chemical storage and placement; which is what this work has studied.
Microbial Controlling Strategy for Upstream Oilfield Process System
Authors: Afizza I. M. , Muhd-Faizul H. A. H. , Mohd-Fadly Y. , Ngau-Uvang J. , Mohd-Hazriq S. I. S.
Published: March 2016

Continuous & effective bio-corrosion monitoring task is highly critical for fast & direct detection of microbial-induce corrosion growth risk pattern within an upstream processing system. This might due to changes in fluid characteristic by time. Failure in detecting such risk changes might trigger for occurrences of serious corrosion-related issue. This study incorporated new detection using AccucountTM energy-based detection kits into monitoring task along with conventional API RB38 SRB test vials & Kitagawa Hydrogen Sulfide gas test. Besides focusing on pipeline microbial growth risk, the monitoring are extended throughout the processing stages to identify the potential & direct microbial risk. The test are carried out at three different sampling time frame; one week after previous treatment, two weeks after treatment & after newly established treatment. The results offer valuable information on the weak point of established treatment program which has previously been overlooked by conventional methods; medium-risk growth in stagnant point, medium risk well-pools & potential solid sedimentation in stagnant point. Time kill test shows high effectiveness of current biocide that been applied into system. Besides, internal corrosion inspection of production separator identified twelve pitting formations. Developing microbial controlling strategy for offshore platform may varies by locations. Accurate and rapid process monitoring leads to correct and well-targeted solutions to potentially detrimental problem. A complete assessment with different set of viewpoints are highly critical in order for a cost effectiveness and further optimize the mitigation method.
Geomechanical Model from Subseismic Resolution Data
Authors: Purnomo Eko Widi , Ghosh Deva Prasad
Published: March 2016

This article demonstrates the extension of subseismic-driven earth elastic model into geomechanic domain. The geomechanical model is becoming uncertain as the impact of subseismic uncertainty. The detail and the uncertainty of the geomechanical model need to be quantitatively defined.

An innovative stochastic partial stacked seismic inversion is proposed to be combined with the geomechanical model built from well to address the problem mentioned. The stochastic inversion uses the energy attribute to control the misfit between the synthetic and true seismic through a Bayesian inference. The prior model of inversion is generated through a geometrical and geophysical perturbation of reflectivity model derived from apparent seismic amplitude. The perturbation is constrained by assigned wavelet, tuning and spectral analysis, and locally varying anisotropy to ensure the adequacy of both vertical and lateral resolution. A geomechanical low frequency model is built by calibrating the low frequency model predicted from the relative geomechanical properties (which is the extension of the relative elastic impedance) inverted from the primary inversion with the geomechanical low frequency model derived from the well log data. The absolute value of the geomechanical property is then estimated based on the frequency content matching between the calibrated relative geomechanical properties and the well log geomechanical model. The related uncertainty of the inverted geomechanical properties is assessed by employing the Markov Chain Monte Carlo (MCMC) sampling methodology.

The proposed method was test to predict the geomechanical model of a fractured volcanic rock basement of Malay Basin. The proposed combination approach between well log geomechanic and stochastic inversion based elastic impedance shows the critical challenge in modeling the geomechanic from subseismic resolution seismic data and promises a good solution. Compared with conventional deterministic inversion, the proposed stochastic inversion provides much better resolution both in lateral and vertical direction, and geologically more consistent. The detail inverted geomechanical properties, inherited by the detail inverted elastic properties, can be used to study the fracture of the potential fractured basement hydrocarbon reservoir.
Design Issues and Modeling Perspectives of Offshore Basin
Authors: Sung Hong Gun , Hong Seok Won , Kim Jin Ha , Yun Sung Hee , Cho Seok Kyu , Nam Bo Woo
Published: March 2016

Recently there are practical concerns for the design of offshore basins since a new large offshore basin named "Deep Ocean Engineering Basin" is under construction by Korea Research Institute of Ships & Ocean Engineering (KRISO). It is known that this would be the world largest one at this time moment. In this paper, we present a number of design issues and modeling perspectives of offshore basin. The main focus is given to basin size and depth together with major facilities for modeling ocean environments such as wave, current, water depth and wind.
Geomechanical Forward Modelling to Optimise Well Trajectories and Avoid Pre-Existing Fractures in a Malay Basin Producing Field, Offshore Malaysia.
Authors: Mohd Nor M. , Abdul Razak M. , Smith S. P.
Published: March 2016

Objectives/Scope: When drilling a micro fractured formation, the fluid differential pressure for wellbore support can be lost and the unsupported formation may fail, causing losses, pack-off and instability. This may be minimized or resolved if the zones of pre-existing fractures are known and the trajectory is optimized to avoid them.

In the Malay Basin, one structure of interest has undergone several periods of stress and faulting, at times, strike-slip in nature. Wrench faults in the area are causing compression and extension. This strain causes micro fractures and voids to be generated. The formation has a secondary porosity but seismic resolution does not allow the pre-existing fractures to be seen. By using a technique known as Geomechanical Forward Modelling (GFM), it is possible to determine natural fracture distribution and avoid these zones, thereby decreasing the risk of encountering instability caused by secondary porosity.

The problems of borehole instability encountered in the area are demonstrated in wells, A1, A2 and A3. The most problematic well was A3. It had many incidents of pack off causing side tracks. In each case, the hole condition was better on side-tracks made higher up the well. It was considered that there is a 3 dimensional extent to the presence of micro fractures. The fracture intensity may have a vertical as well as areal extent. Sometimes wells crossing above or below a zone are not as difficult as through it.

On wells that experienced pack off, cavings at the shaker had an abundance of linear breaks oblique to shale bedding surfaces and suggests the probability of pre-existing fractures. Pre-existing fractures were also seen on image logs.

During planning for an appraisal well, zones with lower plastic shear strain were identified to the North and West of the planned well trajectory by applying GFM. The plastic shear strain profile along the planned trajectory suggested that the target depth will intersect a potential fractured zone. By moving the surface location by only 500 meters, the chances of encountering pre-existing fractures was significantly diminished.

By applying Geomechanical Forward Modelling, (GFM), it is possible to determine distribution and possible locations of secondary fractures, too small to be determined from seismic. This allows for the selection of well trajectories to avoid these naturally fractured zones, thereby decreasing the risk of encountering instability from secondary porosity (pre-existing shear fractures).
Optimizing Drilling Parameters by Integrating Formation Collapse Gradient in Well Hydraulic Modelling to Eliminate Wellbore Mechanical Instability Problems
Authors: Benny B. , Usmar R. , Irawan F. , Setiawan A.
Published: March 2016

Formation collapse gradient is an important parameter for well design and drilling mud selection, especially in a field with history of wellbore instability problems. In modern well design, this gradient is easily neglected since its tendency to be lower than pore pressure gradient. However, some field studies in Indonesia showed that the collapse gradient may be higher than the pore pressure gradient which will result in an unstable well if the bottom hole pressure (BHP) is not well addressed.

In the event of formation collapse, the common drilling practice is to increase the mud weight (MW) being used to a level above the collapse gradient which is time consuming and very rigid operation. Meanwhile, Manage Pressure Drilling (MPD) offers a relatively more dynamic wellbore pressure control by adjusting the surface back pressure (SBP) applied to the annulus for a given MW. Instead of shifting the MW or changing drilling parameters, MPD provide adjustment to the required equivalent circulating density (ECD) or equivalent static density (ESD) based on formation collapse gradient. Additionally, in the event of mud losses due to high ECD/ESD, MPD technique simply lowers the SBP to decrease the BHP without the need to lower the MW.

This paper will utilize hydraulic simulation software to model the drilling window, considering not only pore and fracture pressure gradient, but also involving collapse gradient to optimize recommended MPD parameters including MW and SBP when drilling, pipe connection, and completing the well.
Formation of Project Management Institute Leads to Improved Project Delivery
Authors: Tait Alastair , Kadri Ramzi B. , Kamarudin Zainuddin B.
Published: March 2016

PETRONAS Carigali Sdn. Bhd.'s (PCSB) decision to set up its own Project Management Institute was in recognition of the need to achieve the level of project delivery performance, in terms of safety, cost, quality and schedule, to which it aspired. External benchmarking had shown that it was under-performing in relation to its peers. This paper will show how, during the lifetime of the Project Management Institute, the skill-base within the organisation was broadened and deepened, and project performance improved in comparison with other international operators.
The Economic Assessment of McT Multi Column TLP and Jacket Platforms Application in Multiple Marginal Oil Fields
Authors: Tahar A. , Nurtjahyo P. , Suardin J. , Chaniadi F.
Published: March 2016

Recent offshore drilling success in shallow water and marginal fields development has spurred a tremendous growth in new and innovative solutions that are required to reduce costs, shorten development schedules and exploit previously uneconomical fields. For the redevelopment of Brownfields, a cost efficient offshore production and drilling platform has to increase production capacity within existing field infrastructure. For the Greenfield development, the efficient platform has to offer cost and schedule savings for applications where conventional fixed jacket platforms are uneconomical or where site-specific design requirements or constraints need to be met.

In this paper, we will benchmark an emergent, proven and more cost-efficient technology - Multi Column TLP ("McT"), against the typically utilized offshore platform - "Fixed Jacket." McT is a proprietary technology, patented by Petroneering and its unique design is derived from the commercially-proven technologies of TLP (Tension Leg Platform) and Cell Spar, the two preferred solutions for deepwater development around the world. Having combined the inherent mobility of TLP and simplicity of Cell Spar, McT has now been developed to deliver both the operational reliability and production stability and can be re-used and re-located among disparate marginal fields that were not economically viable using the existing Fixed Jacket technology. This minimizes the CAPEX allocation for the oil & gas operator's individual marginal field project.

This paper will also discuss about the overall benefit of McT technology and its economic advantages for various field development plans (i.e.: of drilling & completion, fabrication to abandonment stages; from single to multiple marginal fields). Further assuming a similar OPEX of both technologies, the cost and schedule of each stage will then be examined and rationalized at different price points of oil. The resultant benchmarking metrics include the accumulative net profit increase over the life of the marginal field (at 5 years).
Remotely Operated Barrier Valve Provides Interventionless Solution for Offshore Vietnam Completion Campaign
Authors: McLeod Bruce , Chinh Nghi Nguyen
Published: March 2016

Considering the scope of work necessary to batch-complete six wells within a tight deadline, the initial outline for an offshore Vietnam completion program required multiple slickline well interventions, not only while on the rig critical path but also during simultaneous operations (SIMOPS). This high frequency of well intervention added considerable time, cost, and potential risk to the overall completion campaign, warranting incorporation of an alternative cost-effective interventionless concept.

Remotely operated barrier valves were evaluated and determined to be a low risk but high value-enabling alternative to running conventional plug-and-prong type barriers during the completion installation. The remotely operated valves' multiple open and close capabilities provided further efficiencies that could be achieved as part of the completion running phase, as well as during SIMOPS when the wells were flowed for cleanup and later suspended for four months until topsides were commissioned.

Two remotely operated barrier valves were pre-installed in their respective nipple profiles (one above the production packer and one below) and run in each of the six completions. The upper valve added value by allowing the production tubing, which included gas lift mandrels, to be pressure tested to full working pressure before setting the production packer. The lower valve facilitated circulating the well to underbalance fluid before setting the production packer and then allowed for subsequent setting and testing of the packer from above. It was later used as a deep-set barrier, allowing blowout preventer (BOP) retrieval and christmas tree installation on the rig critical path before performing further operational steps during the planned SIMOPS.

Using the remotely operated valves in the project provided significant rig time savings of 30 hours per well by eliminating 15 well interventions. This also contributed to reduced health, safety, and environmental (HSE) risks and non-productive time (NPT) potential that are historically associated with slickline-related activity.

This paper illustrates, in detail, the completion installation practice adopted and the many benefits and added value the technology provided to the overall project, both on the rig critical path and during SIMOPS.
Finite Element Modeling of Wet Lay-up CFRP Patch Repaired Corroded Offshore Steel Jacket Member
Authors: Setvati Mahdi Razavi , Mustaffa Zahiraniza , Shafiq Nasir , Isnadi Biramarta , Syed Zubair Imam
Published: March 2016

As the development and application of fiber reinforced polymer (FRP) composite materials to different engineering structures are increasing, composite patching techniques are being considered as alternatives to traditional methods of repair to Jacket-type steel structures. The present paper describes a developed finite element model (FEM) of corroded tubular steel member, representative of offshore steel jacket member, and a FEM of wet lay-up CFRP patch repaired corroded tubular steel member using ANSYS software and ANSYS Composite PrepPost (ACP), which is an add-on module to ANSYS software. The numerical study results reveal that the three-ply composite patch reduces the maximum von-Mises stress, maximum stress intensity and maximum shear stress of the corroded tubular steel member by approximately 20.6%, 18.2% and 18.2%, respectively. Moreover, ply-wise stress and strain results indicate that maximum tensile stress and strain was observed in the first ply and maximum compressive stress and strain was noticed in the third ply. Failure analysis demonstrated that under first applied load and moment there is no critical region or critical failure criteria in composite patch, but under increased axial load of 1300 KN, composite patch fails.
Interface Management - Key to Successful Delivery for a Large, Complex and Integrated EPC Offshore Project
Authors: Poddar Tushar , U Sue
Published: March 2016

Integrated Offshore oil and gas EPC project (IOEPC) is increasingly becoming tougher to manage, as project dimensions and definitions are ever expanding, in order to achieve cost effective field development within the stipulated time frame. The outreach of Interface Management (IM) links directly to all prime project elements to achieve project goals in terms of safety, Quality, schedule & budget. Robust project specific IM plan and procedure is the key document. Systematic model-based IM covering both internal & external interfaces helps to achieve excellent results in project performance. Comprehensive well documented milestone driven Interface Register addresses the flow of issue based information between ‘Requestor’ and ‘Responder’ at the appropriate time, is the essence of success in implementing model based IM system.

For a mega project of TIC > 1.0 BUSD, the model needs to be software driven incorporating various value added algorithms. Web-based IM Module application is a preferred solution for managing remotely when stakeholders are in multiple locations. The benefits of implementing effective IM systems are numerous. The key determinant to derive the outstanding benefits of the IM system is to evaluate the impact in Scope-change, safety, QA/QC and associated risk before accepting data/information from the Responder. One can amply be benefitted by comprehending and adopting the systematic model based IM system. It can potentially save in the excess of tens or hundreds of millions of dollars by avoiding rework, delays, and subsequent production loss for managing integrated offshore mega projects. One of the key lessons learned is when IM is implemented, the possibility of the project success increases dramatically.
Improved High-Speed Mud Pulse Telemetry Performance Under Harsh Conditions
Authors: Emmerich W. , Brahim I. Ben , Akimov O. , Greten A.
Published: March 2016

Mud pulse telemetry (MPT) is the main real-time data transmission technology in oilfield drilling. Constant advances in technology have permitted the oil and gas industry to drill complex well paths and deliver valuable real-time formation measurements. New logging-while-drilling technologies have considerably increased the amount of information collected downhole and therefore the demand for real-time transmission bandwidth.

Reliable high-speed MPT with increased data rates is needed when utilizing complex bottomhole assemblies (BHAs) to deliver information without compromising the rate of penetration. When drilling deep wells with high-density and high-viscosity oil-based mud, transmitting data at high rates introduces challenges for MPT because of the higher signal attenuation and signal distortion. This paper describes enhancements to an MPT system. Improved signal processing at the surface and adjusted signal sequences are used to tune adaptive filters on the receiver side, enabling data transmission with physical data rates of 10 bits/sec and higher in these challenging conditions.

These adaptive filters adjust to new drilling conditions and changes in the MPT signal channel. A test sequence is sent regularly during operation of the system to improve adaptive filters. Improved noise cancellation techniques assist with automation of signal search functions. Filter performance is tested and saved into a database, enabling field personnel to optimize decoding quality at the rigsite. Challenging fields in different regions have successfully run this MPT system and improved decoding capabilities and increased performance compared to offset runs. In addition, the system provided overall higher reliability.

The improvements in MPT enable high-speed data rates in a wider variety of environments, as well as higher data rates in standard settings, lowering the overall cost of drilling wells.