bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Commercially Available Virtual Flow Meters (VFMs)
Authors: Amin A.
Published: April 2015

This report documents a project to improve subsea flow measurements to allow the flowrates of individual wells to be known more accurately. Because production revenues are determined from flowrates, improved flow measurement reduces the financial risk to stakeholders, including producers and the U.S. government. Improved measurement also helps to improve reservoir recovery. In this study, commercially available flow models were evaluated for their suitability as virtual flow meters (VFM).

Virtual flow meters use input from sensors installed at various measurement points (nodes) in the wellbore, on the seabed and in surface facilities. The evaluation of this approach to flowrate metering is particularly meaningful in deepwater subsea applications to complement and backup physical measurements robustly and in a cost effective manner. The soft implementation of this modeling approach leverages already existing information from various measurement devices in the in the wellbore and subsea infrastructure.

The study aimed at assessing the implementation and performance of commercially available VFM software packages using real production data from a subsea well equipped with a subsea multiphase flowmeter (MPFM). The study consisted of three evaluation rounds involving five commercial VFM products. The models were tuned incrementally using the subsea multiphase meter elemental computing parameters consisting of total mass flowrate, gas volume fraction (GVF), and water-liquid ratio (WLR). The results from a series of ‘blind’ tests were compared to actual flowrates with the objective to establish the sensitivity of the models' results to the measurement devices, the parameters used in the tuning, and measurement devices and fluids properties inconsistencies.

Compared to other evaluations, the study is based on existing production data from a live well in which extensive data quality checks were necessary prior to sharing the data with VFM suppliers. Such effort led to consistent and conclusive results from at least three VFM packages that completed all three study rounds. The findings from the study using this data set confirm the robustness of VFM techniques in estimating production flowrates with adequate tuning. It was also established that VFM can be a cost effective and reliable backup measurement instrument to an ailing subsea multiphase meter where partial meter measurement and VFM can restore functionality to the combined flow measurement system.
A Major Offshore Trial of a Free-Standing Mid-Depth BOP Drilling Riser System
Authors: Guo Yongfeng , Ji Shaojun , Tang Changquan , Lim Frank , Zhang Hui , Ching Lishen
Published: April 2015

A major offshore trial of a mid-depth BOP drilling riser system was conducted in 2009 by COSL in 470m water depth of the South China Sea. The objective of the trial was to demonstrate the feasibility of using a shallow water drilling platform to drill in depths which would otherwise be beyond its reach. A free-standing tieback string supported by a buoyancy unit presented an ‘artificial seabed’ and wellhead at an elevation which the platform's existing drilling riser with its subsea BOP could connect to and drill through.

The trial mobilised a 3rd generation semi-submersible drilling platform Nanhai 5, its drilling riser and subsea BOP, a test tieback string, and a fully commissioned buoyancy unit. The full offshore transportation and installation sequences were executed for Nanhai 5 to successfully connect to a mock-up ‘real seabed’ wellhead via the afore-mentioned set-up.

The novel components in the system, particularly the tieback string and buoyancy unit, were instrumented and monitored to study their motion behaviour for correlation against analytical predictions.

In the present day ultra-deepwater drilling world, the interests for such a depth-extending system have revived, in the context of the fleet of modern 3000m-rated drilling platforms wanting to go beyond 3000m water depth. The lessons learnt from the COSL trial bear significant relevance for designing future systems.

This paper describes the trial, its design and planning, certain problems encountered and some recorded system behaviour.
True Downhole Measurement of Differential Pressure
Authors: Hall J.E. , Tiliakos N. , Brown J. , Worst T. , Foster R. B.
Published: April 2015

There is a need to accurately measure the flow rates of well fluids, in both drilling and production operations. While pairs of absolute pressure sensors could be used, a true differential pressure (DP) measurement is required for accurate downhole flow measurement, but has not previously been available. The goal of this work was to design, fabricate and test an HPHT (high-pressure, high temperature) DP sensor at borehole temperatures up to 500 Deg F and pressures up to 10,000 psi. An HPHT absolute P and a DP sensor were developed for subsea flowmeter use in the RPSEA – the Research Partnership to Secure Energy for America – project 07121-1301. However, the diameter of that P-DP sensor cell is too large for downhole applications which require a less than one-inch diameter cell. The 1301 design was modified using solids-modeling software and prototypes were fabricated. Because of the high common-mode pressure, electron-beam welding was required to join the DP cell components together and to the pressure flanges. The completed units were calibrated at ambient conditions and then sent to a certified metrology facility for testing at HPHT conditions.

Calibration of the DP cell showed perfect linearity and good overall accuracy. The maximum error at each of the extremes (500 Deg F and at 10,000 psi) was measured as 0.02% of upper-range limit, even without data processing to make this a "smart" DP transmitter. The cell's overpressure protection functioned to prevent damage to the MEMS DP chip at the extreme conditions. Care must be taken in the electron-beam welding step of the fabrication to prevent the sensor chip's temperature from exceeding its maximum rating. The development demonstrated the ability of the design to meet the requirements for a true HPHT DP sensor for downhole applications.

The measurement capability of a small diameter, true HPHT DP sensor will be of benefit in normal production flow measurement, but it could also be valuable in early detection of a well inflow event during drilling. Observing loss of well control as it is happening could mean the difference between a safe operation and one that is not. Additionally, the DP sensors could also be located at a fixed downhole location, at the sea floor, or at intermediate points (e.g. zones) in the well.
Anti-HS Layer for Flexible Pipe: Full Scale Flowline Qualification Tests
Authors: Chirat M. , Epsztein T. , Lefebvre X. , Minter P. Le
Published: April 2015

For more than 40 years, flexible pipes have been used for subsea oil and gas transportation. One of the main benefits of this technology is that, through an unbounded assembly of steel and polymer layers, the load bearing layers of the pipes are not in direct contact with the transported fluid and the corrosive components such as hydrogen sulphide (H2S).

However, over a long period of time, small quantities of gas, including H2S, are able to permeate through the polymer pressure sheath and reach the metallic structural layers. To avoid this, a new polymer layer able to completely prevent H2S from reaching the annulus has been developed. This layer is called the anti-H2S layer.

As part of the qualification program, an H2S exposure full scale test was performed. A flexible pipe structure with an anti-H2S layer was tested in harsh conditions, continuously exposed to gas containing methane mixed with 1.5% H2S and 5% CO2 at 200 bar (2902 psi) and 80°C (176°F) for 600 days. Several successful integrity tests were performed along the qualification program. After the H2S exposure test, the full scale prototype underwent a hydrostatic pressure test. Pipe dissection and laboratory material characterization were then performed to confirm the efficiency of the anti-H2S layer.

The positive result obtained in the long term H2S exposure full scale test and qualification program demonstrate the efficiency of the anti-H2S layer. The use of the anti-H2S layer concept creates new opportunities in terms of flexible pipe design, especially for ultra deep water and very sour fluid transportation.
Chain Out of Plane Bending (OPB) Joint Industry Project (JIP) Summary and Main Results
Authors: Rampi Lucile , Dewi Fata , Vargas Pedro
Published: April 2015

In 2002, several mooring chains of a deepwater offloading buoy failed prematurely within a very small time frame. These chains were designed according to conventional offshore fatigue assessment using API recommendations. With this first deepwater buoy application, a new mooring chain fatigue mechanism was discovered. High pretension levels combined with significant mooring chain motions caused interlink rotations that generated significant Out of Plane Bending (OPB) fatigue loading. Traditionally, interlink rotations are relatively harmless and generates low bending stresses in the chain links. The intimate mating contact that occurs during the proof loading and the high pretension of the more contemporary mooring designs have been identified as aggravating factors for this phenomenon.

A Joint Industry Project (JIP), gathering 28 different companies, was started in 2007 to better understand the OPB mooring chain fatigue mechanism and propose some mooring chain fatigue design recommendations.

This paper summarizes the various test programs that were implemented within the more than 6 years long project, including full scale fatigue tests on chains, a quasi static OPB stiffness measurement campaign, and tests on small samples addressing the environmental parameter influence on fatigue initiation and crack propagation stages.

The main output from the FEA scope of work, performed to support the experimental tests, will also be described.

Finally, the paper will address the major step that has been achieved regarding implementation of a standard practice in offshore industry using a multiaxial fatigue criterion to address OPB hotspots.
Critical HP/HT Flowline Design Challenges Associated With Deepwater Miocene GoM Fields
Authors: Gavem Tor , Kumar Amitabh , Panga Vijaykumar , Stratton Mike , Harry Jason J.
Published: April 2015

High Pressure / High Temperature (HP/HT) design of a flowline system has become a common design challenge as the quest to extract hydrocarbons has pushed the industry to exploit deeper reservoirs. In recent years, industry has classified systems over ~10,000 psi and over ~300°F as XHPHT (Extra HP/HT). As subsea technology continues to develop, it may not be farfetched to be soon considering UHPHT (Ultra HP/HT) flowline designs.

This paper addresses the key features and challenges of the HP/HT design as applied to the production flowlines of a deepwater Miocene GoM (Gulf of Mexico) field. The dual production flowlines are each ~10 miles long with SITP (Shut-In Tubing Pressure) of ~15000-psi and maximum design temperature of ~300°F (classified as XHPHT). HP/HT specific design challenges are associated with large expansion, global buckling, axial creep, and low-cycle fatigue, which are directly influenced by the flowline length. Even though the tie-back distance to the host is relatively long, the definition of "short" and "long" flowline/pipeline loses its significance due to distributed responses (both "Natural" and "Engineered") of system. Additionally, due to field-specific fluid properties, excessive pressure drops across the well perforation and / or the subsea choke can cause Joule-Thomson heating effects, which must be accounted for in design. This paper further discusses optimization of various design components in order to accommodate small variations in the input parameters (soil, operational transients, installation tolerances etc.) that are crucial with respect to global and local responses.

This case study uses mitigation techniques at pre-determined locations to address the design concerns such as large expansions, rogue (uncontrolled) buckles, axial creep ("walking"), and low-cycle fatigue. By exercising careful review of the iterative assessments and subsequent optimization of the system's overall design, a safe and reliable solution is achieved. HP/HT design philosophy for deepwater Miocene GOM fields form an integral part of design / implementation processes in the field development program and have significant influence on the overall subsea architecture, procurement and construction strategy, operating philosophy, and integrity management plan. Finally, the paper shows a comparison of numerical prediction and the data acquired from the field observations. The predicted system response is in good agreement with the field observations, thereby, validating the overall assessment/modeling approach and confirming the robustness of the system's response.
A Methodological Approach to System Design for Reliability for HPHT Environments
Authors: Amanat Asadullah
Published: April 2015

Ensuring the reliability and integrity of downhole completions systems and equipment for cutting-edge technology wells in the extreme environments of ultradeepwater Gulf of Mexico (GoM) is extremely challenging because of the stringent lifetime and high-pressure, high-temperature (HPHT) requirements set by customers. Although the American Petroleum Institute (API) provides specifications and recommended practices for design and qualification testing of various downhole equipment, those guidelines do not directly address design and testing at the system level.

Failure modes of downhole equipment are still not well understood because of limited historical field data and mission profiles. Implementing an effective and robust reliability and qualification program that analyzes completion systems at all phases of well completions can result in considerable financial savings and eliminate nonproductive time.

This paper presents the planning and execution of a robust Design for Reliability (DFR) and qualification program for downhole well completions systems including lower completions, upper completions and intelligent production systems. The program is a multidisciplinary approach that combines deploying state-of-the-art engineering analysis methods using proven mathematical models, validation/verification testing; and well-defined guidelines to minimize various critical failure incidents. During the planning phase, reliability analyses are conducted to understand and define all major risks in design and lifetime reliability during various phases of the well completion, i.e., from design to manufacturing and assembly to operations. Best practices from various product development functions are also implemented, including supply chain, reliability, manufacturing and operations.

The DFR and qualification program effectively optimizes cost and time without sacrificing quality and reliability by using upfront design optimization and analysis techniques, resulting in a system-level reliability and qualification plan that meets or exceeds the customer's quality and reliability requirements.
Automated Decision Support and Expert Collaboration Avoid Stuck Pipe and Improve Drilling Operations in Offshore Brazil Subsalt Well
Authors: Ferreira Ana Paula L. A. , Carvalho Daltro J. L. , Rodrigues Rogério M. , Schnell David M. , Thomson Ian J. , Baptista Rafael C. , Alves Sandro B.
Published: April 2015

Offshore Brazil is a technically challenging drilling environment due to its size, depth, section length and lithology column characteristics. While drilling in this environment, operators often face nonproductive time (NPT) incidents such as stuck pipe, lost circulation, pipe failure, fishing, and plug and sidetrack. In some cases, operators are forced to sidetrack or even abandon wells after experiencing carnallite-related drilling difficulties.

Drilling through carnallite is challenging because its rate of creep is eight times greater than common halite, or rock salt. Information from wells drilled through similar deep salt sections show that the salt closure rate for carnallite can reach 0.0415 in./hr (1.05 cm/hr) compared to 0.0052 in./hr .01 cm/hr) for halite.

Unfortunately, NPT events repeat themselves in the course of developing a field. One of the reasons the events are not solved is that we are drowning in data. The event symptoms become lost or go unrecognized until it is too late. Early identification of symptoms as they occur while drilling in real time is critical to provide actionable information to the drilling team well ahead of the potential incident.

The methods used enable the drilling team to deliver wells on plan and meet budget projections by recognizing potential drilling problems before they occur. The process integrates three key elements; 24/7 real-time surveillance, case-based reasoning software and the knowledge base of the collaboration team. These three elements combine to provide a fast, practical, real-time solution to avoid NPT.

The multidisciplinary drilling optimization group, integrated with the operator's drilling team, used the automated decision support and timely collaboration for informed decisions, avoiding stuck pipe and saving rig days to free the pipe as well as potential time and cost for fishing, lost BHA and sidetrack.

This paper will illustrate an efficient method of preventing drilling problems before they occur with a decision support tool that provides real-time, case-based reasoning and expert collaboration for enhanced risk assessment and hazard mitigation. The paper provides a case history using the approach taken in the drilling of pre-salt well and discusses the lessons learned during the process.
Steel Catenary Risers (SCRs): From Design to Installation of the First Reeled CRA Lined Pipes. Part I - Risers Design
Authors: Gouveia João , Sriskandarajah T. , Karunakaran Daniel , Manso Daniel , Chiodo Mario , Zhou Daowu , Cao Lingjun , Rao Venu , Vargas Tomaz , Escudero Carlos
Published: April 2015

Steel catenary risers (SCR) have been a favored choice for recent ultra-deep waters field developments subjected to harsh environments and large floating production units (FPU) motions. The design of SCRs in such conditions is always a great challenge where the key issues are the fatigue near the hang-off and at the touch down point; clashing between lines, especially on fields with a large number of wells and high payloads on the production unit. This paper describes the solution provided by the Buoy Supporting Risers (BSR) concept which has recently been installed in the Santos basin offshore Brazil.

Subsea7 detailed the original concept of BSR system, from the design to fabrication and installation. The BSR concept combines several benefits to overcome the challenges of installing SCRs on ultra-deep waters, such as: allowing decoupling between installation of risers/flowlines and the platform, reducing payload on the production unit, very small dynamics transmitted from production unit to the risers, resulting in significant less fatigue issues. Also, the BSR concept reduces the risks associated with clashing and interference due to the smaller dynamics when compared to traditional coupled solutions. Fabrication is also addressed to highlight main challenges associated to assembling and welding clad and lined pipelines.

In this paper the key aspects of the design and qualification are presented. Due to sour and CO2 service requirements for the production and water injection risers, it was decided to use corrosion resistant alloy (CRA) mechanically lined pipe for the entire line, with the exception of the top and touch down sections, where metallurgical clad pipe was used. Considering its novelty, a significant amount of qualification and testing was demanded. Among the technological innovations part of the SCR package is the first successful application of a pressurized mechanically lined pipe by reel-lay method. The solution involved an extensive qualification program, including full scale tests on vessel. The methodology and rationale to allow the application of high strain levels during spooling mitigating potential risk of wrinkling within the internal liner, had to be addressed during the detailed design by extensive Finite Element Analysis and validation tests.

The SCR itself, due to de-coupling of motions by the buoy, have negligible dynamic response from vessel motions, thereby behaving almost like a static system with robust fatigue performance. The only meaningful fatigue in SCRs is due to current induced VIV and is mitigated using strakes. There was negligible potential clashing with adjacent SCRs.

This paper provides a summary of design and qualification work carried for SCRs lined pipes installed in the BSR system and a discussion regarding main outcomes.
Real Time Monitoring of Oil Based Mud, Spacer Fluid and Piezoresistive Smart Cement to Verify the Oil Well Drilling and Cementing Operation Using Model Tests
Authors: Vipulanandan C. , Ramanathan P. , Ali K. , Basirat B. , Farzam H. , Head W. J. , Pappas J. M.
Published: April 2015

Well control operations are critical to ensure successful cementing of the oil wells with any losses. With increased drilling depths for production of oil and gas there are greater challenges due changes in the natural geological formations with in situ pressure and temperature conditions. Recent case studies on oil well failures have clearly identified cementing and drilling mud contamination as some of the issues that resulted in various types of delays in the cementing operations. For a successful cementing operation, it is critical to monitor the drilling and cementing operation during the installation so that necessary remediation can be made to minimize the delays and losses of cement. At present there is no technology available to monitor cementing operations without using buried sensors within the cement sheath and also monitor the movement of the drilling mud and spacer fluid to determine the changes real time during the installation of oil or gas wells.

In this study, small well models were designed, built, and used to demonstrate the concept of real time monitoring of the flow of smart drilling mud, space fluid and smart cement and hardening of the cement in place. Also, a new method has been developed to measure the electrical resistivity of the materials using the two probe method. Using the new concept, it has been proven that resistivity dominates the behavior of drilling mud and smart cement. LCR meters (measures the inductance (L), capacitance (C) and resistance (R)) were used at 300 kHz frequency to measure the changes in resistance. Several laboratory scale model tests have been performed using instrumented casing with wires and thermocouples. When the drilling mud was in the model borehole the measured resistance was the highest based on the high resistivity of the drilling mud. Notable reduction in electrical resistance was observed with the flow of spacer fluid and cement. Change in the resistance of hardened cement has been continuously monitored up to about 100 days. Also, a method to predict the changes in electrical resistance of the hardening cement outside the casing (Electrical Resistance Model – ERM) with time has been developed. The ERM predicted the changes in the electrical resistances of the hardening cement outside the cemented casing very well. In addition, the pressure testing showed the piezoresistive response of the hardened smart cement.
Calculation Method of Three-Dimensional Fracture Pressure in Shallow Layers of Deepwater
Authors: Deng Song , Fan Honghai , Ji Rongyi , Zhou Yuyang , Shen Weige , Gao Yuan , Han Fuxin , Dai Rui
Published: April 2015

Fracturing pressure is a key index to characterize the formation characteristics, and it is also a basic factor to determine well structure and safety. Furthermore, accurate calculation of formation fracture pressure is of great significance to determine the safe density window of drilling fluid precisely. Deepwater shallow nature is changeable due to shallow flow, shallow gas and other natural disasters. Despite the accurate calculation of the shale formation fracture pressure through computational model, the existing methods still exists some deficiency such as the lack of pertinence and intuitive of special layers.

This paper proposes a computational method of 3-D fracture pressure. Firstly, it calculates single point of fracture pressure in deepwater shallow layers by lateral pressure coefficient method which is more adaptable to the actual engineering. Then 3-D density data and 3-D velocity data can be worked out reasonably based on logging constrained seismic inversion technique by using the Jason inversion software. Besides, it uses the Kriging interpolation method by combining inversion density data and inversion velocity data to calculate pressure of each stratum. Finally, 3-D fracture pressure can be obtained by applying interpolation technique again. After that, it designs the formation fracture pressure software for display,

This paper presents a case study of Yingqiong basin in South China Sea. First, it uses constrained inversion to get 3-D density data and 3-D velocity data, and then obtains the 3-D fracture pressure through the method based on the 3-D seismic data collected. It can conclude the spatial distribution characteristics of the 3-D fracture pressure of the shallow region. And the value of the region has been compared with the drilled wells fracture pressure gradient measured values sub regionally.

Through the comparison and analysis of the measured value, this method effectively improves the calculation precision of 3D fracture pressure. It can be applied in the engineering design to improve the engineering safety, thus it can be widely promoted.
Steel Catenary Risers (SCRs): From Design to Installation of the First Reel CRA Lined Pipes. Part II: Fabrication and Installation
Authors: Maneschy Ricardo , Romanelli Bruno , Butterworth Christopher , Pedrosa José , Escudero Carlos , Vargas Tomaz
Published: April 2015

As part of the ultra-deepwater field development of the Santos Basin, 300km offshore the Brazilian coast, the Sapinhoá and Lula NE pioneering riser system was successfully installed by Subsea 7, acting as a contractor for Petrobras and partners (BG E&P Brasil and Repsol Sinopec Brasil, in Sapinhoá Field, BG E&P Brasil and Petrogal Brasil, in Lula NE Field). The full Engineering, Procurement, Installation and Commissioning (EPIC) project scope comprises the design, fabrication and installation of 4 buoys of 2800 tons moored 250m subsurface, of which 2 connect to the Floating Production, Storage and Offloading unit (FPSO) Cidade de São Paulo and 2 to the FPSO Cidade de Paraty; 27 Steel Catenary Risers (SCRs) with 3.9km each, 27 Pipeline End Terminations (PLETs) and anchorage suction piles at 2140m water depth.

This Buoy Supporting Risers (BSR) system concept presents several advantages to overcome the challenges of installing SCRs on ultra-deep waters, such as, allowing decoupling between installation of risers and the production unit, reducing payload on the unit, reduced risks associated with clashes and very small dynamics transmitted from production unit to the risers, resulting in significant less fatigue issues.

Due to sour and CO2 service requirements for the production and water injection risers, it was decided to use mechanically lined pipe for the entire line, with the exception of the top and touch down sections, where metallurgical clad (metclad) pipe was used. Consequently, a significant amount of qualification, testing and inspection associated to welding lined and metclad pipes was required.

In order to install Corrosion Resistant Alloys (CRA) lined pipes with a Reel-Lay vessel, a novel methodology for water pressurized spooling and pipelay was developed to mitigate the risk of liner damage during installation. Full-scale pressurized spooling trials were done ahead of the pipelay campaign for testing and validation of this methodology. In addition, analyses were performed to evaluate the BSR system behaviour during SCRs installation and to minimize buoy de-ballasting interventions.

This paper describes the faced challenges and solutions engineered in the steel catenary risers' fabrication and installation scopes.
The Impacts of the Safety Culture in Oil and Gas Operations
Authors: Floris Vinio V.
Published: April 2015

Safety culture is defined as a system comprised of values, norms, competencies, attitudes and patterns of behavior that determines the commitment, style and proficiency of an organization's safety performance. This paper describes the complexity of oil and gas operations, and points that a weak safety culture could produce severe individual or organizational incidents with catastrophic consequences. This paper introduces a Safety Maturity Matrix (with a focus on the oil and gas industry) which explains the path from the pathological stage to the generative (top) level. This model brings together all the elements of a safety culture to achieve and sustain an environment that evolves with ever-changing techniques and challenges.
Well Construction Challenges in the Pre-Salt Development Projects
Authors: Pinheiro R.S. , Santos A.R. , Marques M. , Schnitzler E. , Signorini D. , Tomita R.A.
Published: April 2015

The ambitious plan to develop and produce the prolific Pre-Salt reservoirs in the Brazilian Santos Basin was kicked off by the discovery of the gigantic Lula Field in 2006 (previously known as "Tupi"). For Petrobras, the first decade of this century was therefore marked by the significant challenges imposed by these complex carbonate reservoirs, requiring the accelerated introduction of new technologies and innovative approaches to well construction.

This article describes the history of well construction in the offshore Brazilian Pre Salt area. It summarizes the evolution in well design that resulted from the implementation of innumerable "lessons learned" that were acquired since drilling of the first wildcat well in the Pre-Salt Cluster.

The commulative experience of more than 100 wells drilled and 29 wells completed (to date), has resulted in a progressive reductions of time and CAPEX required for the construction of the development wells in the Santos Basin.
Reservoir Characteristics Interpretation by Using Down-Hole Specific Energy With Down-Hole Torque and Drag
Authors: Laosripaiboon Lertsak , Saiwan Chintana , Prurapark Ruktai
Published: April 2015

The cost reduction has become the most challenge in oil and gas exploration. Many technologies have been developed to optimize the drilling and completion operation. One of the solutions is to reduce the cost of perforation. Although, well logging, neutron porosity, resistivity and gamma ray, can indicate the suitable zone for perforation, there still have some perforated zones which cannot be the production zones due to insufficient pressure of reservoir for the production. Thus, the more accurate decision chosen for the perforated zone will reduce well completion cost.

Specific energy is referred to work input to drill a volume of rock and also used to determine the drilling efficiency by comparing with confined compressive strength (CCS). For the perfect drilling operation, down-hole specific energy should be equal to CCS. One of the parameters, which lead the fluctuation in down-hole specific energy is inlet pressure from reservoir. The zone which has higher down-hole specific energy than other zones at the same lithology will have a drilling problem. Thus, the zone which can be the reservoir from well logging data with drilling problems is possible a potential production zone.

The combination of results from the down-hole specific energy and the well logging data can bring more accurate decision in choosing the perforated zone by avoiding the low potential zone. However, a down-hole specific energy calculation needs down-hole torque (DTOR) and weight on bit (DWOB) data, which requires additional budget for measurement using the commercial sensor, thus the friction calculation is preferred to save the budget. In this research, the friction analysis will base on Aadnoy et al [1] and Hareland et al [4] models was used to calculate DWOB.

The assumption of down-hole specific energy was verified using data from two wells in Thailand to calculate the potential zone. The results showed the zone which have been chosen from both of logging and down-hole specific energy can be the production zone and the zone which only chosen from logging data may be a non-potential zone.
Integrated Geohazards Assessments offshore Azerbaijan, Caspian Sea
Authors: Unterseh S. , Contet J.
Published: April 2015

The aim of this paper is to present the methodology implemented to assess the geohazards potentially affecting a subsea development offshore Azerbaijan and the main findings. The site investigated is located on the continental slope of the Caspian Sea in water depths ranging from 50m to 600m.

A preliminary geohazards assessment has been made from the available 3D exploration seismic and revealed large scale geological features, including a giant mud volcano, regional scale Mass Transport Complexes (MTC) and a large slope failure scar at seabed. Nevertheless, the resolution of the 3D dataset was of insufficient quality to address the drilling hazards with enough confidence and a serie of high resolution geophysical site investigations has been recommended. They include a dense 2D high resolution seismic survey and a high resolution Autonomous Underwater Vehicle (AUV) survey, aiming at characterizing seabed and near-seabed geohazards. These geophysical site investigations have been complemented by a dedicated geotechnical survey in order to provide preliminary geo-mechanical parameters and to build a proper geological model. All these surveys have been achieved very early in the development project in order to have sufficient flexibility to adapt the intended subsea field layout and to minimize the exposure to geohazards.

The high resolution dataset revealed an unsuspected complexity in the recent shallow geological history of the site, resulting from the close interaction of tectonics, mud volcanism, high sedimentation rates, mass transport deposits and gaseous fluid upward migration. The gaseous fluid migration is currently active and is at the origin of many geohazards, with gas accumulation at shallow depths, seepages at seabed along faults, mud volcano and pockmarks, and with occurrence of methane derived authigenic carbonates (MDAC). The gaseous fluid migration and accumulation may also be related to the occurrence of slope failures observed at shallow depths within the soil.
Sand Production in Sand Controlled Completions and Topside Wall Loss Assessment
Authors: Huebner Ben , Redpath Wendy , Riley Sean , Joshi Nikhil
Published: April 2015

The most frequent completion method used in deepwater Gulf of Mexico is the use of gravel pack with sand screens. These are used to minimize and possibly avoid any sand production in the production system. Sand production from subsea wells tied back to a host can be a significant detriment to the integrity of the subsea infrastructure as well as the processing facilities at the host location. Hence, it is important to have effective sand control measures as well as reliable methods to measure sand, if produced.

This paper discusses three case studies where sand production occurred even with sand control measures in place. The discussion is focused on the challenges associated with detection and quantification of produced sand as well as its impact on the subsea and topside infrastructure. The cases are for a dry gas well, a gas condensate well, and a black oil well. All three cases are subsea tie-backs to different host facilities.

In these cases, the sand detection methods used are intrusive and acoustic type sand detectors, as well as centrifuge measurements of the produced fluids. The challenges associated with these methods are discussed in this paper. It is concluded that, at least in one instance, the acoustic device is reliable in identification of sand production but unreliable for quantification of the sand volume.

In addition to produced sand measurements, inspection measurements which indicate wall loss of piping at the arrival of the fluids to the host facility are discussed. An attempt has been made to correlate the wall loss from inspection with erosional model predictions. It is concluded that the uncertainty in measured data is significant and, to pursue such a correlation, improvement in sensor reliability as well as accurate sand production data is required.
Examples of Broadband Processing and its Effect on Amplitude Versus Offset (AVO) Products
Authors: Laha Sampad , Casady Mark
Published: April 2015

Presence of ghosts in conventional marine seismic images reduces imaging resolution and bandwidth of the data. Removing these ghosts can increase the resolution of the data and make the data broadband resulting in a better image. We use a broadband processing technique to achieve this. This technique is applicable to marine acquisition, including conventionally acquired datasets. In this paper, we present various broadband examples from different parts of the world to probe the imaging enhancement. Broadband processing has enormous potential for increasing resolution, and thus adding value to seismic data. However, few studies have been performed on AVO analysis of broadband processed data. This paper also examines the AVO aspect to demonstrate the effect of broadband processing on AVO and its attributes.
Dynamic Simulation of Integrated Pipeline and Process Models to Investigate Slug Flow Impact on Subsea Compact Separation
Authors: Garner B. , Petit P. , Unnam J.
Published: April 2015

Dynamic simulation using integrated pipeline and process simulators is implemented to investigate slugging effects on subsea compact separation design and control. The pipeline model includes well geometry and production and export pipelines, while the process model includes subsea separation and topside first-stage separation. The two simulation models interface at multiple locations where pressure and flow data are shared. This allows for continuous dynamic simulation from the bottom of the wellbores to topside separation. This coupled simulation model is used to study production over multiple operating scenarios in order to investigate potential slugs and their impact on subsea compact separator design and control.

Accurate prediction of slugs is critical for the safe and efficient design of subsea compact separators. Integration of the pipeline and process models allows for accurate slug prediction by the pipeline model and control system response by the process model. Operating scenarios can be studied to optimize compact separator design, controller tuning parameters and operating philosophy under slug flow conditions.
CFD Applications in Offshore Engineering
Authors: Darvishzadeh Tohid , Sari Ali
Published: April 2015

Offshore engineering applications generally require interactions between offshore structures and fluids in the form of oceanic flows or blast waves. A correct estimation of the forces caused by these flows is crucial in designing highly reliable structures to be used in offshore environment. Computational Fluid Dynamics (CFD) has been used to analyze the fluid behavior and its influence on offshore structures by solving the equations of fluid motion. However, resolution of all spatial and temporal scales of the flow requires very time-consuming and complicated CFD simulations. This paper demonstrates various applications of simplified CFD methods in solving problems associated with offshore technologies. We present results of shock wave interaction with modular buildings and large pipes using Fluid-Solid Interaction (FSI) method and comment on their structural behavior and damage levels. Moreover, the impact of a drop object on a subsea pipeline protection structure is investigated using FSI and structural analysis. Furthermore, the air temperature increase inside a modular building is estimated using computational analysis of free convection coupled with heat transfer analysis of the modular building. Lastly, we will report CFD results of velocity enhancement of offshore columns and the hydrodynamic interact ion amongst groups of cylinders. Star-CCM+ is used for most of the CFD computations and is coupled with Abaqus for solving FSI problems. The results demonstrate how critical parameters such as fluid forces could be computed using simplified CFD approaches while often coupled with detailed structural analysis using finite element method to reduce their conservatism.
The Integration of 3D Seismic With the Ultrahigh Resolution Data From the Marine Survey: Recognizing and Quantifying Several Challenging Features for Subsea Production Installations in Complex Environment Offshore Brazil
Authors: Martin Federico D. , Batalla Luis F. , De Oliveira Pinheiro Rafaela L. , Escalona Luis G. , El Mistikawi Seif , Tiffany Justin , Pryne Daniel E. , Haneberg William C. , Campbell Kerry J.
Published: April 2015

A large integrated marine site investigation was conducted from 2013 to 2014 offshore Brazil in water depths ranging from 100 m to 2,900 m. High-resolution geophysical survey, geotechnical, and geologic data were collected using a variety of tools designed for deepwater applications. Approximately 4630 line-km of autonomous underwater vehicle (AUV) data, piston cores, jumbo piston cores, and cone-penetrometer test data were collected. Results will be used for siting, routing, foundation design, and installation of development and production facilities. Interpretation of existing 3D exploration seismic volumes provided a regional geologic setting from the discovery wells in deepwater to the outer edge of the continental shelf shoreward and outside of the concession block. Analysis of the AUV and core data provided detailed qualitative and quantitative information to characterize and assess potential geohazards that could affect the large area where future facilities are planned. Potential geohazards identified during the integrated study include: rugged and steep topography; scarps, seafloor grooves, and mass-transport deposits associated with past seafloor failures, and potential for future failures; faults with seafloor expression; seafloor channels; and sediment waves.
Practical Solutions for HTHP Offshore Reservoir Surveillance
Authors: Kamble Prakash D. , Thombare Akshay A. , Dakwale Pratik V. , Botre Rutuja P.
Published: April 2015

Chasing new plays often make operators reach to complex and non-traditional reservoirs. Especially, at offshore hydrocarbon discoveries it becomes critically important to characterize the fluid, assess pressure profile and understand the flow behavior. This work is a case history of successfully implemented reservoir surveillance techniques at HTHP offshore green field.

The key challenges included presence of high pressure pockets/ panic zones, high cost of well testing with additional slickline & logistics, uncertainties of fluid phase and flow behavior at really tough HTHP conditions. These challenges were addressed by utilizing a flexible mix of modern day technologies. This successful case on reservoir surveillance is elaborated in the present abstract. Heavy duty dual packer Modular Dynamic testing: The dual packer formation evaluation tester could withstand 400F and 13500 psi formation pressures; while keeping drawdown in ultra low permeability sandy siltstone.HTHP sour gas Permanent Down-hole Gauges (PDG): The presence of CO2 (nearly 10%) and H2S (110 ppm) with steam fractions was fatal for the wellbore integrity. Use of sour-proof Permanent downhole gauges to actively monitor the BHP & BHT as close to perforations.Extreme performer Production Logging Techniques (Extreme PLT) for >400F zones: At high temperature he fluid phase behaviour, pay-zone resistivity and thin transition zone is hardly predictable. To overcome the uncertainties of fluid type, hold and thief zones the extreme PLT tools played the judging role.

This paper shows insights of learning and how it was utilized as a solution. Huge saving was achieved on accounts of i. Fluid characterization and facility selection, ii. Recognized panic/ pressure inversion zones for future drilling campaign, iii. Saved cost of repeated slick-line operations for well testing by real-time well performance monitoring with PDG.

The learning phase was relatively longer but the learned decision added significant value to the project. Use of tools and tailor made combinations made Reservoir Surveillance much easier, cost effective and ultimately reduced the uncertainties. The field has been put on production within relatively shorter timeframe.
Single-Component 3D Deghosting and Crossline Interpolation
Authors: Wang Ping , Ray Suryadeep , Nimsaila Kawin
Published: April 2015

For marine towed-streamer seismic data, the sparse crossline sampling imposes a Nyquist limitation for many processing steps that require either f – k (frequency-wavenumber) or f – p (frequency-slowness) transforms in the crossline direction. For this reason, 3D deghosting and crossline interpolation have been considered extremely difficult to perform using only single-component towed-streamer seismic data. We present a progressive sparse t – px – py inversion scheme to perform 3D deghosting and crossline interpolation using single-component seismic data. Using field data examples, we demonstrate that our 3D deghosting algorithm effectively attenuates the ghost and works better than the GWE (Ghost Wavefield Elimination) method for full-azimuth data with strong 3D effects. We also demonstrate that by using our algorithm, it is possible to perform single-component joint 3D deghosting and crossline interpolation in the presence of strong spatial aliasing in the crossline direction. We show that the interpolation of the high-frequency events may be sub-optimal in deep time windows when the signal-to-noise ratio of high-frequency events is low.
Vision 2020- Delivering Great Process Safety Globally
Authors: Grounds Cheryl , Berger Scott , McCavit Jack
Published: April 2015

Vision 20/20, developed by the Center for Chemical Process Safety (CCPS), looks into the not-too-distant future to describe how great process safety is delivered when it is collectively and fervently supported by industry, regulators, academia, and the community worldwide.