bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improving Production in a Brownfield by Optimising the Placement of Horizontal Water Injector in Thin Clastic Reservoir: A Case Study from Malay Basin
Authors: Jamaluddin M.S.R. , Hanalim L. , Suwarlan W. , Permanasari D. , Santoso G.I. , Brahmanto E. , Lwin M.M. , Alang K.A. 
Published: February 2015

Most of the hydrocarbon bearing sands in Angsi, Malay Basin, have been identified as thin sands with average thickness of less than 8-m. Thus, reservoir development has become challenging. One of the effective ways to develop this field is by drilling highly deviated or horizontal wells. Based on the field study, water injection was the chosen technique to manage the reservoir pressure during depletion in the reservoir.
After long production, one of the thin reservoirs in Angsi has become highly depleted and was in critical need of injection. This reservoir is distributed widely in the field, with an average thickness of one meter. Due to the sand thickness, the most efficient way to place an injector well is to drill horizontally in the depleted part of the reservoir. However, placing a horizontal well in this depleted thin sand posed significant challenge for the drilling operation, including to land accurately at the target sand, avoiding premature exit from the target reservoir due to geological uncertainties, and managing the borehole pressure to avoid differential sticking of the BHA. For formation evaluation, the high angle effects such as anisotropy, close vicinity to shoulder beds, and lateral property changes will make the quantitative interpretation more complex.
To address the challenges, a combination of logging-while-drilling measurements namely near-bit gamma ray, average and deep directional resistivity for boundary detection, azimuthal density, neutron porosity, and formation pressure measurements were used to land and optimize the well in the thin sand, executed by a collaborative experts from subsurface, drilling, and geosteering team. High angle well modeling was also conducted to extract the true formation properties and explain the high angle effects to the measurements. As a result, the well was placed optimally in the thin target reservoir for 300-m length as per objective, with improved quantitative petrophysical evaluation.
In this case study, the comprehensive work from pre-drill planning, drilling execution including 24 hours real-time monitoring to steer the well, to post well evaluation and modeling will be discussed. Lessons learnt, best practices, and recommendation of drilling and evaluating similar well will also be shared in this paper.
Housings, Closures, and Connectors for Underwater Instruments
Authors: Williams Albert J. 
Published: February 2015

Underwater sensors require either pressure and water resisting housings or pressure exposed but water isolated packaging. This paper describes types of housings and their characteristics.
Pressure exposed packages are lightweight and inexpensive, relying upon the inherent pressure tolerance of many electronic circuits and discrete components. But most sensors and complete instruments are more conservatively constructed, tested, and calibrated in dry accessible packages that are housed in pressure resisting cases.
Criteria of corrosion resistance, size, weight, cost, and compatibility with associated other housings and cables must be considered. Choices of material include glass, ceramic, aluminum, stainless steel, and titanium. Closures often influence choice of material. Design of closure from vacuum sealed dry lapped glass to O-ring seals offer economy versus user accessibility. Penetrators for electrical connections are easily installed in metal end caps but optical or inductive connections can be made through glass. Corrosion protection and/or isolation from dissimilar metals are essential with metal housings. Plastics, including fiber reinforced plastics, offer some of the advantages of metals with reduced corrosion but bring new concerns including cold flow and water wicking. Metal backed plastic housings obviate some of these concerns at a cost in complexity.
All of these play a role in design and selection of sensor or instrument housings. Experiences with most of these housings are presented with lessons learned and cost to benefit analysis is offered for each. This should serve as a guide for design of instrument housings for various applications
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.
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.