bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Temperature on Gel Treatment under Various Reservoir Wettability Conditions
Authors: Shen G.X. , Lee J.H. , Lee K.S.
Published: February 2015

Heterogeneous reservoirs which especially characterize high permeability contrast bring about excessive water production. To avoid disproportionate water production, permeability reduction techniques are proposed and gel treatment is well-known as effective one of them. Previous studies have revealed the gelation of various gel types is sensitive to temperatures. Also, wettability of reservoir determines different performance. To date, most of former researches are carried out only concerning relationships between wettability and gel treatment or between temperature and gel treatment, mainly by experiments. To overcome these limitations, the assessment of non-isothermal gel treatment requires a model as a function of temperature under consideration of wettability of reservoir. Using a reservoir simulator including the model for wettability, extensive numerical studies have been performed to investigate the effect of temperature on the water-oil ratio and cumulative oil recovery. Analyzed target is the layered reservoir which has severe permeability contrast in vertical direction and low vertical communication with an injector under gel treatment followed by water flood. Results from a number of scenarios of different temperatures of reservoir and injection fluid clearly prove the temperature dependency of performance. The model can be used as quantitative tool to evaluate the comparative studies of gel treatment with respect to temperature dependency under different wettability of reservoir. The significant improvement is observed in both water-wet and oil-wet reservoirs as temperature elevates. However, improvement of performance of gel treatment according to temperature in oil-wet reservoir shows different results comparing with that in water-wet reservoir. As reservoir temperature increases, water-oil ratio in water-wet reservoir decreases more rapidly than that in oil-wet reservoir. Increases in oil recovery of oil-wet reservoirs are obtained while slight decreases in water-wet reservoirs. In terms of injection fluid temperature, the higher injection temperature, the more improvement in water-oil ratio is noticed for water-wet reservoir than oil-wet reservoir.
Jack Up Suitability for South China Sea Sites
Authors: Nancy Chan , B Rohani Muhammad Joehan , Bt M Hazizy Rozana , B Abd Rahman Azam , Jalil Azri B A
Published: February 2015

The decision to use a particular type of Jack Up for a particular site is guided by site specific assessment requirements. The offshore oil and gas industry is guided by ISO 19905–1 and also SNAME 5–5A but since the industry is subject to many varied requirements of marine warranty surveyors, competition between rig owners and urgency of rig usage, operators such as Petronas Carigali Sdn Bhd (PCSB) are at times confronted with technical aspects of site specific assessments that are not trivial to rationalize in terms of selecting Jack Ups that are suitable and fit for purpose for any particular site.

Taking into consideration PCSB considerable amount of soil and shallow seismic survey data and accounting for the expected increase in rig utilization in the next five years in the region, PCSB is embarking on a project to provide regional mappings that can provide a tool for assessments of suitability of jack up from a risk mitigation perspective. This paper will present the basis for establishing the need to provide a regional mapping for suitability of Jack Ups by investigating aspects of actual versus predicted leg penetration analyses, jack up structural aspects, geohazard assessments and relating to failure experiences to postulate that jack up rig failures can be mitigated by a risk assessment and mitigation framework.

PCSB involvement in an in house study makes it amongst the first oil and gas operators in the region to benefit from its accumulated jack up related experiences and knowledge of soil data in various South China Sea sites. This paper will outline the benefit of having a regional Jack Up suitability mapping in minimizing potential jack up failures thus optimizing operational costs.
Assessment on Semi-submersible Drilling Unit with Fatigue Cracks
Authors: Wang Xuejun , Cheng Zhiping , Kuang Jinlu , Gu Hai
Published: February 2015

Description of the material:

Semisubmersibles have been widely used in deepwater applications. During their service life, fatigue cracks may be initiated. The presence of such cracks at critical locations can compromise the safety of the whole structure. In such cases, the ultimate strength check alone cannot meet the structural integrity requirement. Therefore, there is a need to further analyze the risk of fracture failure caused by crack extension to prevent potential losses of life or property and damage to the environment. To that end, the Engineering Critical Assessment (ECA) approach has been accepted in several design codes. Based on the principles of fracture mechanics, this method uses the conservative Failure Assessment Diagrams (FADs) to judge the impact on safety of a given flaw under specified loading conditions. However, the method in existing codes is limited to well-defined and standard welded structures. Further study is needed when ECA is applied to semi-submersibles. Accordingly, the development of the FADs specifically for critical components of semisubmersibles and the corresponding assessment procedure would be necessary. In the paper, failure assessment has been conducted on a typical twin pontoon semisubmersible platform with surface cracks at hot spot locations based on the proposed FADs. Global FE analyses were performed under design loading conditions. A very detailed local FE model at the critical locations was established for the fracture crack driving force analysis.

Application:

The proposed procedure can be used to perform failure assessment on semi-submersibles with fatigue cracks at critical locations. The assessment result can be useful in making a rational repair or no-repair decision and improving the inspection strategy.

Results, Observations, and Conclusions:

Failure assessment has been conducted on a typical twin pontoon semisubmersible platform with surface cracks at hot spot locations. The generic level 2A curve in the BS7910 was compared with the constructed FADs to examine whether it is conservative or not.

Significance of Subject Matter:

Since the method in existing codes is limited, further study is needed when ECA is applied to semisubmersibles. The development of the FADs specifically for critical components of semisubmersibles and the corresponding assessment procedure would be necessary.
Improved Soft String Model for Non-Buckling Horizontal Section Drill String Torque Modeling of Changbei Project
Authors: Liu Yongjun , Gao Erhu , Jamshidian Hormoz , Tayalan Subramaniam , Wang Jianping , Lu Zaohua , Luo Lei
Published: February 2015

Drill string torque and drag is one of the major limitations of horizontal wells. Torque and drag modeling is regarded as an invaluable process to assist in well planning and to predict and prevent drilling problems. Soft string model are widely used in the industry, which has good matching result with field data when bit off bottom, but has low matching accuracy in horizontal wells when bit on bottom. In horizontal section the string is in compression when drilling. The compression force is not always in the same direction with well bore axis. The compression force has a component perpendicular to well bore and this force should be considered when modeling the drilling torque in horizontal wells. Off bottom torque and on bottom torque should use different models as the string in horizontal section has different status.

Horizontal section drill string is separately discussed in the paper. By study the off bottom torque, on bottom torque and bit torque, the WOB effect on torque was captured. String status when bit on bottom was analyzed. New model was presented considering the WOB affect along drill string for horizontal section of wells. Model validity was checked by field case at Changbei project.
De-risking Hydrocarbon Prospects by Amplitude Versus Angle (AVA) Modelling and Attribute Analysis
Authors: Rajput Sanjeev , Ring Michael
Published: February 2015

The present study reveals the application and value of Amplitude versus Angle (AVA) modeling and attribute analysis for preparing a de-risking model hydrocarbon prospects. Public domain seismic and well data from the Australian offshore was used and AVA modeling applied together with attribute analyses to study the patterns in the rock properties for de-risking hydrocarbon prospects.

In quantitative applications of seismic data, AVA modelling and attribute analysis are widely used for lithology and fluid analysis. AVA analysis has wide applications in the exploration domain including AVO class identification and discrimination of hydrocarbons in the sediments. As AVA attributes are directly related to elastic-property contrasts associated with rock and fluid properties this approach can be used as an alternative to more sophisticated methods like seismic inversion.

In order to perform the AVA modeling and attribute analysis a series of forward models in association with rock physics models integrated together. Aki-Richards method that relates AVA attributes to contrasts in the three elastic parameters P-wave impedance (Ip), S-wave impedance (Is) and density (RHOB) is used to generate synthetics and the amplitude responses have been measured for different fluid substituted scenarios. For quantitative applications the AVA attributes, AVA intercept and gradient (A & B) were cross plotted and the patterns in rock property studied. The results reveal that synthetic seismic responses together with the AVA analysis show changes for different porosity scenarios and a prospect based trend of decreasing or increasing can be established.

AVA modelling and attribute analysis ultimately leads to a better lateral prediction and discrimination of hydrocarbons. It may be concluded that assessing the effect of fluid-substituted logs for different lithologies and associated AVA seismic response improve the prediction in reservoir characterization.
Challenges in Identifying and Quantifying Hydrocarbons in Thinly Bedded, Laminated, and Low-Resistivity Pay Zones
Authors: Oifoghe Stanley
Published: February 2015

High-resolution formation resistivity borehole images acquired in low-resistivity formations drilled with non-conductive mud systems can help in the analysis of structural dip, fracture systems, depositional environments, borehole stability, and net-pay identification in thinly bedded sequences. The high-resolution net-sand analysis from these resistivity borehole images_in conjunction with results from a multicomponent induction logging service_helps to determine an accurate net-pay, even in thinly bedded intervals.

Laminated formations frequently exhibit electrical anisotropy where resistivity measured perpendicular to the bedding (Rv) is significantly higher than resistivity measured parallel to the bedding (Rh). This occurs when high-resistivity sand layers are interspersed with low-resistivity shale layers. Analysis based on conventional resistivity tools will often bypass pay zones in thinly bedded sand-shale sequences. They measure horizontal (bed-parallel) resistivity, which is dominated by the low-resistivity shale laminae, not by the high-resistivity, hydrocarbon-bearing sand laminae. Average resistivity over these tools' vertical resolution can be misleadingly low and computed water saturation pessimistically high. This is a major cause of "low-resistivity pay" in thinly bedded laminated formations.

In the Niger Delta where a comparison was made between the Water Saturation computed from Conventional Resistivity and that from Multi-Component Resistivity, there was a 30% reduction in the computed Water Saturation, which gave a substantial increase in the computed bulk volume hydrocarbon.

The multicomponent induction logging service is designed to efficiently and economically identify and quantify hydrocarbons in laminated, low-resistivity pay zones. It enables the determination of bed-parallel [RHorizontal (Rh)] and bed-normal [RVertical (Rv)] resistivities. These resistivity measurements, when utilized with the laminated sand-shale analysis and stable tensor petrophysical model, enable the determination of the true formation resistivities and water saturations, and thus lead to accurate identification, and quantification of hydrocarbons-in-place.
Design and Construction Challenges of Lan Do 13Cr Flowline System
Authors: Sam Ming-Tuck
Published: February 2015

The Lan Do gas field was developed to supplement the depleting reserve at existing Lan Tay field. It is a crucial development as 22% of the electricity capacity for Vietnam is dependent on gas supply from Lan Tay production facilities. Gas from Lan Do field contains 1.2% CO2 which required corrosion resistant alloy for the flowline. 13Cr was selected at an early stage to take advantage of preferential procurement agreement with the pipe manufacturer. 13Cr can be a cost effective solution for sweet CO2 service. However, there are special requirements that must be addressed for this material to be successfully deployed.

13Cr is known to be susceptible to hydrogen induced cracking resulting from the high potential generated by normal cathodic protection system. Specific industry guidance on the method to address this risk is still lacking. Current solution has been essentially limited to proprietary developed diode controlled anode system. For this project, a proprietary designed diode controlled aluminium alloy anode system was used. The presence of carbon steel fittings, equipment and structures where normal aluminium anodes were attached, imposed a strict requirement for electrical isolation from the 13Cr flowline. Electrical isolation techniques such as monolithic isolation joints were used for the flowline connections, whereas Teflon coating was introduced to isolate the structures. Specific welding details between 13Cr and CRA clad pipes were made to address differing thicknesses between these materials.

Among the challenges in the installation phase was to land an in-line sled structure on a seabed characterized by mounts and valleys. To achieve a level seabed, remedial measure using grout bags dumping was used. The amount of grout bags dumped was large, requiring about 250 m3 of grout bags at a water depth of 185 m, which was rarely done.

This paper describes the innovative approaches taken to address the challenges in engineering the 13Cr flowline and solutions developed to enable construction and installation of the subsea structures on a very rugged seabed. The flowline was successfully installed and received first gas on 7 October 2012.
Unique Use of Splitter Wellhead Design for Fit for Purpose Casing Design and Offline Work
Authors: Damasena Edwin , Azrynizam Mohd , Kasim Hilmy , Ismail Hamdan , Mos Anuar
Published: February 2015

Berantai field is a Marginal field locatedoffshore East Coast of Peninsula Malaysia. Berantai is the first Risk ServiceContract in Malaysia with gas production commencing ca. 2 years after signingthe RSC. A minimum size unmanned Wellhead Platform was installed in 2011 accommodating18 wells in 9 × 36in. conductors. The Splitter Wellhead system is a 2 (wells) in1 (conductor) system and is selectedto assist in designing minimum size platform deck facilitating surface piping and manifolds for 3types producer (highpressure gas, low pressure gas, and oil wells). As the production ratedemand certain size production tubing be used, unconventional casing designconcentrically inside the 36 in. conductors has been selected in order to allowsuitable size production casing be used. Inconductor sharing wells, it is standard that the 2nd casing string is a guide(sacrificial) casing string terminating at the conductor shoe depth. In Berantai the Operator optedto set this guide string some 600 m deep in up to 60 degrees inclination, believed to be the 1st time this conceptis used. Extensive " offline" work in conjunction with batch drillingand completions allow the Operator to save significant time and cost. Accesories werebuilt andprocedures developed to allow a multitude of tasks, such as cementing casing, installing lower and upper landing ring, Xmas tree, slick line operationsperformed "offline"saving rigtime in the order of 48 hrs per well
A Time Domain Update Method for Reservoir History Matching of Electromagnetic Data
Authors: Katterbauer Klemens , Hoteit Ibrahim , Sun Shuyu
Published: February 2015

The oil & gas industry has been the backbone of the world's economy in the last century and will continue to be in the decades to come. With increasing demand and conventional reservoirs depleting, new oil industry projects have become more complex and expensive, operating in areas that were previously considered impossible and uneconomical. Therefore, good reservoir management is key for the economical success of complex projects requiring the incorporation of reliable uncertainty estimates for reliable production forecasts and optimizing reservoir exploitation. Reservoir history matching has played here a key role incorporating production, seismic, electromagnetic and logging data for forecasting the development of reservoirs and its depletion. With the advances in the last decade, electromagnetic techniques, such as crosswell electromagnetic tomography, have enabled engineers to more precisely map the reservoirs and understand their evolution. Incorporating the large amount of data efficiently and reducing uncertainty in the forecasts has been one of the key challenges for reservoir management. Computing the conductivity distribution for the field for adjusting parameters in the forecasting process via solving the inverse problem has been a challenge, due to the strong ill-posedness of the inversion problem and the extensive manual calibration required, making it impossible to be included into an efficient reservoir history matching forecasting algorithm. In the presented research, we have developed a novel Finite Difference Time Domain (FDTD) based method for incorporating electromagnetic data directly into the reservoir simulator. Based on an extended Archie relationship, EM simulations are performed for both forecasted and Porosity-Saturation retrieved conductivity parameters being incorporated directly into an update step for the reservoir parameters. This novel direct update method has significant advantages such as that it overcomes the expensive and ill-conditioned inversion process, applicable to arbitrary reservoir geometries and enables efficient integration with real field crosswell EM data.
A Step Change in Managing Technical Integrity in the Oil and Gas Industry - A Case Study
Authors: Refsdal Ingbjorn , Ostby Erik
Published: February 2015

Today's business environment is more competitive and technologically complex. From a business perspective, managing risk and ensuring predictable and sustainable operations are vital necessities. Technical integrity plays a key role and the owner needs to have control of all facilities in terms of technical safety and production regularity both in a day-to-day and a lifetime perspective. Measuring and managing technical integrity is a the synthesis of several work processes like production, maintenance and inspection, modifications, safety reviews and technical audits, competence building and knowledge. This complexity makes it challenging to manage technical integrity in a coherent and consistent manner towards common and aligned business goals.

The paper outlines Statoil's risk based approach to an integrated, cross-disciplinary system for management of technical integrity of offshore and onshore production facilities. An initiative was launched in 2010 to develop and implement a new technical integrity management for measuring and follow-up of the technical condition of safety barriers, well-, production- and transportation systems, and load bearing structures. This initiative was named TIMP - Technical Integrity Management Programme.

The TIMP concept consists of:A comprehensive and ambitious competence programmeA standardised work process to follow up and visualise technical integrityA methodology to assess the technical condition at equipment-, system and facility levelAn IT tool to visualise the technical integrity and assist daily work processes.

Details of each element of TIMP are further outlined in the paper, and the challenges and learning from the development and implementation of TIMP on 40 assets are summarized. While TIMP supports the daily work processes for managing the technical integrity of all production systems and safety barriers, a technical verification is carried out for all safety barriers every 5 years at all Statoil operated assets, offshore and onshore. This verification program is named Teknisk Tilstand Sikkerhet - TTS (eng: Technical Condition Safety) and together TIMP and TTS form the core technical integrity management for all assets operated by Statoil.
Should Subsea Pipeline Stability in North West Shelf of Australia be designed Against 10,000-Years Return Period Storms? (Preliminary Insight)
Authors: Ibrahim Malik M.
Published: February 2015

It has been noticed a pick up in the storm level across the world, which have been recorded to induce significant wave heights greater than 100years return period (RP). The events have been partly blamed on the climate change. This is one possible reason which has triggered pipeline designers, nowadays, to consider 10,000years RP storms for subsea pipeline on-bottom stability assessment in North West Shelf (NWS) region. Another possible reason is the remote locations and harsh environment, which would make it difficult or otherwise, costly, to carry out repairs, inspections, and measurements activities of the subsea pipelines in the area. Furthermore, it has been acknowledged that an offshore platform design has applied similar approach, although this is more likely due to the fact that the platform might be manned during its operation. Therefore, one might accept an overly robust design as the solution to the above issues. However, one might question the basis of 10,000years RP storm selection as a solution, since this can necessitate a costly design.

This paper presents some alternatives to the existing 10,000years RP storms requirement. A program was developed to carry out structural reliability analysis (SRA) of pipeline on-bottom stability, while considering the occurrence (RP) of the loadings. The program was validated and calibrated to DNV RP F109 results, and then used for the higher RP storms assessment. Design cases were generated and data were adopted from an existing project within NWS region.

Preliminary SRA results demonstrate that the selection of lower design RP is negotiable. The discussion also touched on cost versus risk analysis (other method of selecting higher RP storm), as well as soil stability during this level of storm.

The amount of infrastructure savings could be significant if a lower design RP can be accepted, while not compromising the design reliability.
Advanced Global Nonlinear Dynamic Simulations of Flexible Riser Systems
Authors: Majed Arya , Cooper Phil
Published: February 2015

Large-scale simulation of flexible riser systems with detailed models has been called an industry "quest". Advanced commercial finite element analysis packages can model the complex geometry and multi-layer interaction of flexible risers; however, the massive computational requirements of these models for spans of just a few meters makes them impractical for larger scales. These models are limited to local analyses; post-processing tensions and curvatures from the usual riser global analysis software where the flexible riser is modeled with line elements. The accuracy of armour stresses from this global/local analysis procedure is impacted by a series of approximations in the global/local procedures including the over-simplified global analysis model, the boundary conditions of the local model, and the computational requirements for the local model preventing a time-consistent treatment of global analysis inputs. The resulting armour stress predictions are often over conservative impacting fatigue life predictions and field deployment.

This paper expands on recent published papers by the authors (2013 OTC and 2013 ISOPE) on applications of nonlinear dynamic substructuring to computationally efficient detailed flexible pipe simulations and presents a large-scale nonlinear dynamic simulation of a flexible riser system. The substructure finite element models are 8-layer shell element detailed models including geometrically nonlinear effects and multi-layer interaction via friction hysteresis. Armour stress time-histories are directly recovered from the large-scale analysis using stress transformation matrices completely by-passing the local analysis.

This advancement allows for a more detailed and realistic large-scale nonlinear simulation of the flexible riser system resulting in the direct recovery of detailed armour stress time-histories without having to resort to a secondary local analysis of a detailed sub-model. The methodology is capable of efficiently incorporating multi-layered pipe models in a fully geometrically nonlinear dynamics setting including armour layer friction hysteresis. This significantly expands the current industry practice of global/local analysis with simplified line model representations. This powerful and computationally efficient method is implemented in a stand-alone computer program.
Geotechnical Design and Installation of Suction Anchors for the Goliat FPSO, Offshore Norway
Authors: Solhjell E. , Blaker O. , Knudsen S. , Rahim A.
Published: February 2015

Goliat is the first oil field to be developed in the Barents Sea, and thus sets the industry standard as activity migrates ever further north. Eni, together with partner Statoil, has chosen to develop the field using Sevan Marine's cylindrical FPSO concept. This FPSO is designed for operations under the challenging conditions encountered in the Barents Sea and is equipped to meet the strict environmental requirements stipulated for operations in the Arctic climate. The FPSO is moored using 14 suction anchors, with 6 anchors in the west cluster, 4 in the north cluster and 4 in the southeast cluster. The soil layers of relevance for the suction anchor design are a surface layer of very soft sandy clay and a soft to firm slightly sandy clay with some gravel to at least 20 m depth. All 14 suction anchors were designed with the same geometry to allow flexibility during the installation phase. The anchor holding capacity was evaluated using Finite Element analyses. The successful installation of the suction anchors was performed in spring 2013 to allow hookup of the FPSO as planned. This paper describes details of the suction anchor design and installation process as a reference for further work in Arctic regions.
Process Stability of Multi-Compander Refrigeration Trains for Floating LNG Application
Authors: Hashim Hasnor Hassaruddin , Muhd Ali Fadzrul Izwan , Rusman Andriny
Published: February 2015

Conventional land based LNG plants utilizes hydrocarbon-based refrigerant systems driven by large compressors. For floating LNG plants, gaseous N2 refrigeration system is preferred due to the compactness of the refrigeration equipment and the less hazardous nature of gaseous N2 when compared with liquid hydrocarbon refrigeration system. Due to the low heat capacity of N2, companders (expander-compressor) are required to maximize the cooling duty instead of JT valves. Multiple compander units are required to handle the pre-cooling, liquefaction and sub-cooling of the natural gas. To provide process flexibility and equipment maintenance window, parallel N2 refrigeration trains are required for floating LNG plant. PETRONAS Floating LNG 1 facility will be the first floating plant in the world, utilizing only gaseous N2 as the refrigerant to produce LNG.

The controllability of the N2 liquefaction is the main concern due to the large number of rotating equipment as well as load balancing the parallel N2 refrigeration trains. Specific analyses need to be conducted on the liquefaction system due to the complexity and highly interactive nature of the process, leading to possible process instability. An integrated dynamic model using PETRONAS's iCON dynamic process simulation software was developed and utilized to conduct several operability studies, focusing on normal start-up and shut-down, refrigeration load switching from single to parallel N2 refrigeration trains, increase and decrease in LNG production, feed disturbance from production wells and equipment malfunction.

Result shows that there is a highly interactive dynamic response between the companders and the heat exchangers due to the tight process integration. Disturbance to one compander may cause cascading effect through the other companders, which can cause compander overspeed or surge condition. This necessitates prudent analysis of the operating scenarios to ensure operability and carefully planned controller design for stable operation. Additionally, being the first such refrigeration configuration in the world, correction of perception that operation will be similar to the conventional hydrocarbon-based refrigeration LNG facilities is an issue to address.
Water Source and Flow Direction Detection in a Heterogeneous Fracture Carbonate Reservoir: Challenge and Solutions_A Case Study in Indonesia
Authors: Sanjaya Sanggum , Quintero Luis , Iyer M.S. , Diametrica Septian , Praveen Florence , Soendaroe Achmad , Harkomoyo Harkomoyo
Published: February 2015

Detecting the source of water production remains a major challenge during evaluation of fractured carbonate reservoirs. In heterogeneous formations, when the horizontal section passes through a fracture or set of fractures, improper drawdown can allow formation water to flow through these conduits, increasing water cut and blocking hydrocarbon production.

On the contrary, in cases of horizontal wells with three phases of fluid flow, the presence of inflow control devices (ICDs), sliding slide doors (SSDs), slotted liners, and swell packers can add to the complexity of the logging environment and exasperate the ability to accurately quantify production using a production logging tool (PLT).

Using horizontal production logging alone can help identify the point of water entry; yet, in cases of slotted liners, it can be difficult to pinpoint the source of water and the direction of flow. The use of oxygen activation can help identify water movement inside or behind liners and confirm the direction of flow. The integration of both techniques helps minimize uncertainty and enhance interpretation.

This paper discusses a case study from Pertamina Hulu Energi-West Madura Offshore (PHE-WMO). The difficulties associated with identifying water sources in horizontal wells drilled in complex carbonate reservoirs completed with ICDs, SSDs, and swell packers are discussed. It documents a well with high water cut, making water point identification more challenging. Also, it discusses the advantages of using a spectral flow log with a horizontal PLT, versus using the latter only.
Floating LNG Development - Challenges and Achievements
Authors: Ahmad Hamzah , Abdul Wahab Iskandariah Roslan , Suaib Mohd Hany
Published: February 2015

The PETRONAS Floating LNG concept was envisaged to monetize stranded gas resources as part of the effort to turn Malaysia's 2% hydrocarbon depletion rate into 3% growth. The two floaters for offshore Sarawak and Sabah will increase the country's LNG production capacity by 8% (2.5 MTPA). The fast track nature of the project present a challenge to both the Gas and upstream Business in meeting the target date. Extensive technology selection exercises we conducted in finalizing the turret and mooring,, gas treating, liquefaction, LNG cargo containment and LNG offloading systems. Designers and licensors have done rigorous design optimization and marinization studies on impact of floater motion and evaluated against an extensive criteria:Proven and established onshore and offshore track records as well as experience or involvement in the delivery of LNG plantsDesign robustness and efficiencyOperating envelop and flexibilityInherent safe design

Main challenge includes optimizing the flexibility of the process to accept the widest range of known and anticipated feed gas quality. Technology and equipment selection for the topside processes required extensive investigation into vendors' readiness to design and supply natural gas receiving, treating, liquefying and LNG storage and offloading equipment for first time utilization in the open sea environment. Processes and equipment design have taken into consideration the design motion envelope, calculated blast loads, acceleration and sloshing effects while keeping within the topsides weight, footprint, environment and regulatory constraints. The nitrogen cycle liquefaction process presented a unique challenge in commissioning attributed to logistics requirement and the extreme complexity of the process and machinery controls.

Success in managing the complexity of the facilities design and construction within the extreme constraints of technology and constructability will be the ultimate triumph for the PETRONAS Floating LNG Project to become a benchmark and model for similar scale Floating LNG projects.
Deepwater Growth in Asia Pacific and Growing Regional Installation and Pipelay Vessels Capability to Meet the Challenges
Authors: Dash Biren Kumar
Published: February 2015

As demand for oil & gas continues to increase, Asia will continue to lead growth in global energy demand. Growing demand will move the industry more into Deepwater as the production from existing shallow water development is depleting at a steady pace. Global deepwater Capex spending is expected to rise from a 38% share in 2012 to a 53% share of global offshore Capex by the year 2017. Although majority of these Capex will be spent in deepwater triangle Brazil, West Africa and Gulf of Mexico, Asia Pacific (APAC) region will be the fastest growing in deepwater development. Malaysia, Indonesia, China, India and Australia together will contribute to 85% of the Deepwater drilling and EPCIC spending in APAC region. Although there are many challenges to meet the growing deepwater offshore construction need in APAC to execute these demanding projects, availability of deepwater installation, pipelay and SURF vessels will be the key to meet timely availability, overall cost competitiveness with lower mobilisation/demobilisation cost, regional offshore execution experience, regulatory requirement as well as managing diverse monsoon weather windows across the region. This paper presents various forthcoming deepwater developments in the region with focus on deepwater pipelay involving steep S-lay/ J-lay requirement and availability of regional offshore installation, deepwater pipe lay and SURF vessels to meet the challenge that will be posed by future deepwater development in the region.
Detection and Removal of Naphthenate Deposit in Oil Well
Authors: Mohamed A.S. , Goyal A. , Mohd Ismail M.D. , Munainni G. , Amar Singh J.K. , Ismail M.Z. , Anwar M.
Published: February 2015

Oil wells which produce high acidic crude especially asphalt-base crudes tend to yield naphthenate (cycloparaffin) as deposits. This is a major flow assurance issue as it reduces the oil production in the wells and also causes napthenate induced emulsion. The objective of this work is to focus on diagnosis of oil producing well which have the tendency on forming napthenate deposits along with inorganic scale/corrosion product. In this paper, two wells from an oilfield offshore of East Malaysia were used as a case study to detect the presence of naphthenate. Analytical testing was conducted to detect napthenes deposit in these wells. Tests such as total acid number (TAN) analysis, cationic and anionic analysis on water, pH of crude and also x-ray diffraction (XRD) on deposit were conducted to understand the occurrence of the napthenate solid. A speciality micro-emulsion formulation was designed to improve the productivity of the well by injecting into the tubing/around wellbore to dissolve/disperse these napthenate deposits embedded with inorganics. One of the well of the case study, Well A is diagnosed to be impaired by napthenate deposition. Well A was observed to have production drop from 1200 bpd to 300 bpd in 7 years. During this period, skin increased from 30 to 65. Formation blockage was identified as the root cause based on the Productivity Index (PI) trending established from several pressure build up surveys (PBU) and flowing gradient surveys. After the treatment, the liquid rate increased to 700 bpd with significant reduction in watercut.

The application of this study is to provide a guideline towards early detection of naphthenate and possible chemical remedial to revive the well productivity. Thus, promotes preventive measures and mitigation plan which can be devised and replicated.
The Future of Electric Controls: Trees and Subsea Processing
Authors: Mahler Carsten , Awo Richard
Published: February 2015

Since2008 the world's first all electric production controls system is operating inthe Dutch sector of the North Sea. Valuable feedback is constantly beingreceived and lessons learnt are being implemented for future generations of all electric technology. A new generation has been developed for the operation ofSubsea Production Systems, ie. X-Mas Trees and Manifolds in particular. But withSubsea Processing systems becoming more and more accepted by the industry, all electric technology could be a key enabler for further enhancement of SubseaProcessing applications. For instance with the subsea factory emerging on thehorizon, a key requirement for complex systems is that control valves be operated in a continuous operation mode, either manually or in a closed loop(PID). For surface applications this generally poses no problem as varioustechnical means are at the industry's disposal ranging from pneumatic, hydraulic or electric actuation control. For subsea this is different, withlonger step-outs and deep water depths having a hydrostatic pressure constraintreaction times). These severe conditions require special equipment capable of handling the increased process control challenges. Controlling valves fasterbecomes increasingly important, and in general demands electric controlcharacteristics. The majority of applications so far have used hydraulic actuators, although there are systems currently in build which will use electricactuation control. This paper will focus on explaining electrical technology, itshistory, and identify its advantages especially when used for long offsets, zero discharge requirements and complicated process controls. The paper willalso provide a vision of the control technology for the future, drawing fromproven Electro-Hydraulic and electric control systems of today and considering current technology developments.
3-D Mapping for Fire and Gas Detection
Authors: Kek Chua Kien , Yang Tan Ping
Published: February 2015

An increasingly competitive environment has put intense pressure on Oil & Gas operators to design and operate facilities in a more cost efficient manner without compromising safety. Fire and gas detection systems play an important role as a safety barrier in process safety management and the adequacy of detection coverage is crucial. PETRONAS has developed 3-D visualization software to accurately quantify detector coverage for correct detector placement.

This software provides a quantitative means of evaluating flame and gas detector coverage which is not available via conventional engineering methods. It also improves accuracy over conventional 2-D methods, evaluating coverage around irregular-shaped equipment at different elevations. PETRONAS' Fire and Gas Mapping software can be used to evaluate detection of various hazards by different detection technologies such as combustible gas (point, open path and ultrasonic), flame (UV, UV/IR, IR3 and CCTV) and toxic gas (point and open path). It has been successfully deployed to 27 downstream and upstream sites and counting, covering both green field and brown field facilities.

With a greater emphasis on safety and economics in Oil & Gas facility design and operations, fire and gas mapping is an invaluable technical solution and will become the benchmark in determining detector placement for the industry.
Solution to Cement Integrity Evaluation in Long Extended Reach Wells: New Record in South China Sea
Authors: Cai Jun , Gao Yongde , Zhang Mingjie , Cui Lei , Guo Hongzhi
Published: February 2015

The development wells in South China Sea today are mostly extended reach wells with a measured depth of about 4000m and a high deviated or horizontal displacement of over 3000m. The accurate assessment of cement bond is given even more attention because of the cementing challenges in such environment: the uncertainty of cement distribution in highly deviated intervals due to uneven mud removal, the difficulty in evaluating two-stage cement job with both light and heavy slurries pumped in one section. Furthermore, rising cost concern of offshore operations requires an efficient manner to acquire comprehensive integrity evaluation data without extending rig time.

The combination of ultrasonic and flexural attenuation measurements was adopted in this project for cement integrity evaluation, conveyed with a wireline tractor. Analysis from the combined measurements discriminates the materials behind casing circumferentially regardless of cement density, and identifies liquid or gas filled channeling in cement sheath. The flexural wave imager reveals the "Third-Interface" information that illustrates annulus shape and casing centralization, from which a three-dimensional cement sheath image can be generated. We conducted the operation rigless by tractoring the tool-string down for over 3300 meters to the target depth, to acquire good quality data in a single run.

In this paper field examples are presented to explain the workflow of getting a more definitive cement integrity answer. We will also discuss how the new method aids to understand why the integrity losses occur in certain sections by analyzing the Third-Interface information uniquely provided by flexural waves, hence to suggest improvement actions in future cementing jobs.

This method gained more explicit cement integrity evaluation result with detailed graphical annulus information comparing with limited outputs from conventional acoustic measurements. Furthermore, this solution was launched for the first time in South China Sea and great efficiency was demonstrated with a new tractoring distance record in China offshore operation, which saved 2 days rig time in comparison with previous jobs conveyed by drill pipe.
Selecting a Safe and Reliable Drilling System for New Deepwater Challenges
Authors: Brandt Havard
Published: February 2015

The Oil & Gas industry continues to explore and develop ever more challenging and difficult hydrocarbon prospects. Also Asia is experiencing a push into deeper water, exploring reservoirs with higher pressure and more difficult and complicated formations, i.e. fractured carbonates. These operating conditions results in an increased interest for more novel drilling systems, i.e. offshore managed pressure drilling. But how safe and reliable are these new systems?

A general perception is that new technology introduces more risks, and there are a number of examples of new technology not meeting expectations with respect to reliability and performance. What would be the consequence of a failure in these new drilling systems? To further complicate the situation, the recent Macondo and Montara blowout has put a increased pressure on the drilling industry to demonstrate safe and reliable drilling operations; there is no tolerance for failure.

One of the challenges with this risk adverse perception on new technology is that conventional systems are typically only evaluated on the basis of their past track record, with little or no considerations to the more complicated and challenging operating environments. Consequently, the drilling contractors experience more drilling problems when operating in these new environments, i.e. stuck pipe and lost circulation. These issues result in high operating costs due to loss of drilling mud and non-productive time (NPT), but they also represent a potential safety risk as these drilling events may trigger a well control incidents.

To provide a more realistic risk picture and have a better basis to compare alternative drilling systems, DNV has together with the industry developed a methodology to assess and quantify the risk of blowouts related to a specific well operation. This risk based assessment is based on a systematic assessment of the drilling rig, drilling equipment, operating conditions, sub-surface conditions and drilling and casing program. In this paper the methodology is outlined, and a case example related to a specific drilling operation in a fractured carbonate reservoir of the Eastern coast of Sulawesi, Indonesia, is used to demonstrate the methodology.
Influence of CO2 Nucleation Rate Towards Cryogenic Separation Technologies in Bulk CO2 Separation from Natural Gas
Authors: Md Jalil A.A. , Rostani K. , Ahmad Samawe R. , Othman N.A. , Esa M.A.
Published: February 2015

Marginal gas fields containing large concentrations of CO2 is a technical challenge to develop due to the low CO2 concentration requirement in the sales gas. One of the CO2 - Natural Gas separation methods being studied to develop the field is to use phase separation method in separating CO2 with natural gas. The principle of these gas separations units lies in the cryogenic sciences in the separation unit, causing condensation (and crystallization) of CO2 out of the mixture. Therefore, it is important to understand the concept of nucleation of CO2 to properly design the gas separation units.

An adiabatic expansion experiments is performed in pulse expansion wave tube (PEWT) (1, 2 &3). In this experimental set-up, CO2 nucleation is induced in a high-pressure expansion wave tube, where rapid controlled pressure and temperature decrease is induced. The nucleation is measured by means of laser scattering and extinction signals. Moreover, the onset of crystallization can be measured if the expansion is sufficiently deep for the liquid droplets to evoke liquid-solid transition. Similarly, a new parallel experimental set-up was commissioned to allow for more experimental runs per day. Gas mixture in Expansion Chamber (PEC) is brought into nucleation by subjecting it to a sudden change in temperature and pressure. When temperature continues to decrease, the solid-liquid saturation curve in the phase diagram is passed, and crystallization occurs. In this way the experimental setup open the possibility to determine Wilson points, crystallization points, and nucleation rates for multi-component gas mixtures. The onset of nucleation, crystallization, and the measurement of droplet growth is measured by means of laser light transmission and scattering.

In both set-ups temperatures below -100°C is reached. Experiments in both setups for CO2 in NG mixture confirmed theoretical temperature predictions. The results are comparable to the nucleation theory which predicts the onset of nucleation and nucleation delay. These parameters are then used to design CO2 - Natural Gas Separation devices.