scholarly journals COBRA Riser Concept for Ultra Deepwater Condition

2013 ◽  
Author(s):  
Tomy Nurwanto ◽  
Daniel Karunakaran ◽  
Ricardo Franciss
Keyword(s):  
Water Depth ◽  
Oil And Gas ◽  
Sudden Change ◽  
Cost Effective ◽  
Mooring Lines ◽  
Strength Performance ◽  
Design Performance ◽  
Cluster Region ◽  
Sea Bed ◽  
Flexible Jumper

Offshore ultra deepwater field is being promising as the future of oil and gas reserves. However, the development of ultra deepwater field posed many challenges, in particular, on the selection of the riser concept. Long suspended length of riser will significantly increase the vessel payload. High external hydrostatic pressure on the riser will increase the probability of collapse failure. Large dynamic motions of the vessel and large vessel offset yields potential buckling issues at the touch-down-point (TDP). In addition, potential fatigue problems due to vessel motions and soil-riser interactions also present at TDP area. Large current speed in deepwater field might also lead to vortex induced vibration (VIV) which eventually will contribute to significant fatigue damage for particular riser sections. By looking into these challenges, it is very important to select the most appropriate riser concept for the ultra deepwater field. Catenary Offset Buoyant Riser Assembly (COBRA) as newly developed hybrid riser concept offers a solution to overcome the challenges in ultra deepwater field. In general, COBRA consists of a catenary riser section with a long-slender sub-surface buoyancy module on top which is tethered down to sea bed via two mooring lines. The catenary section from top of the sub-surface buoy is connected to the floater by a flexible jumper. This flexible jumper can effectively absorb the floater motions, which give significant improvements for both strength and fatigue performance on the overall system. As a hybrid riser concept, this concept offers cost effective solution by avoiding all the expensive bottom assemblies that normally needed for a hybrid riser concept. This paper focuses on COBRA riser concept specifically for Santos Basin Central Cluster region at 2200 m water depth. It is observed that there is common sudden change phenomenon on the current direction in Santos Basin area. The effect of bidirectional current is analyzed, and the comparison with unidirectional current is discussed thoroughly. The analyses are focused on the global strength design performance under extreme environmental load and global fatigue design performance of the riser due to wave induced and VIV induced. The results clearly indicate that COBRA riser concept has a robust design and it is feasible for 2200 m water depth, in particular for Santos Basin Cluster Region area. It is also shows that COBRA riser has sufficient strength performance even for extreme bidirectional current.

Tension-Based Tension Leg Platform: Technologies for Ultra Deepwater Applications

2010 ◽  
Author(s):  
Nagan Srinivasan
Keyword(s):  
Water Depth ◽  
Oil And Gas ◽  
Cost Effective ◽  
Gas Production ◽  
Harsh Environment ◽  
Tension Leg Platform ◽  
Oil And Gas Production ◽  
Sea Bed ◽  
Horizontal Wave ◽  
Vibration Problems

This paper is about technology of the Tension Leg Platform (TLP) for use in ultra deepwater to support dry-tree in oil and gas production. New TLP concept for ultra deepwater development is introduced in this paper. A technically feasible and cost-effective artificial sea-bed is used to ease the tendon design practical at such deep water in harsh environment. The truss-pontoon is utilized to reduce the vertical and horizontal wave loadings. A simple and slim hull easy to design, fabricate, transport and install is obtained. Installation method is illustrated. Optional riser-support tower is proposed to make production risers feasible in 8000 ft of water depth with no riser pre-tension to the hull and with no vortex induced vibration problems. The paper enhances the TLP capability in deepwater.

Wet Tree Semi-Submersible With SCRs for 4,000 ft Water Depth in the Gulf of Mexico

2011 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao ◽  
Sherry Xiang
Keyword(s):  
Gulf Of Mexico ◽  
Water Depth ◽  
Cost Effective ◽  
Integrated System ◽  
Fatigue Performance ◽  
Strength Performance ◽  
Field Development ◽  
Vessel Motion ◽  
Optimum Solution ◽  
Mitigation Methods

This paper presents a design of a deep draft wet tree semi-submersible with steel catenary risers (SCRs) for 4,000 ft water depth in the Gulf of Mexico (GoM). The integrated system of hull, mooring, and SCRs is discussed. The design challenges of SCRs are highlighted and results of SCR strength and fatigue performance are presented. A comparison study on strength performance of various types of risers under the GoM environment criteria is performed. The assessment of extreme strength responses from various riser and hull configurations provide guidelines for the best hull selection. Sour service requirement creates challenges in the fatigue design of the production riser system at such water depth. Integrated mooring and riser design provides an optimum solution. It’s found that the majority of riser fatigue damage at touch down zone is generated by wave loading & resultant vessel motion and vortex induced vessel motion (VIM). Several fatigue mitigation methods are suggested to improve the riser fatigue performance, such as planned vessel repositioning. The conclusion of this study is that deep draft wet tree semi-submersible with SCRs can be a cost effective solution for field development at 4,000 ft water depth in the Gulf of Mexico.

Polyester Mooring for Ultra-Deepwater Applications

2002 ◽  
Author(s):  
Shankar S. Bhat ◽  
Christian A. Cermelli ◽  
King Him Lo
Keyword(s):  
Water Depth ◽  
Oil And Gas ◽  
Synthetic Fiber ◽  
Mooring Lines ◽  
Deepwater Drilling ◽  
The Past ◽  
Design Methodologies ◽  
Essential Components ◽  
New Material ◽  
Industry Experience

In the past few years, drilling for oil and gas has been conducted in increasingly greater water depth, with recent records approaching 10,000.0 ft water depth. Ultra-deepwater drilling demands increased performance from mooring systems, such as tight watch circle, enhanced reliability, and ease of deployment. Synthetic fiber mooring lines are essential components to help meet these demands. Because of the lack of industry experience with this new material, advanced studies are required to properly design and optimize polyester-based mooring systems for ultra-deepwater drilling. This paper provides information on the performance of polyester mooring lines, based on coupled and un-coupled analyses and compares various design methodologies.

Steel Lazy Wave Riser Design for Semi-Submersible in Harsh Environment

2014 ◽  
Author(s):  
Jingyun Cheng ◽  
Peimin Cao
Keyword(s):  
Water Depth ◽  
Optimal Solution ◽  
Cost Effective ◽  
Harsh Environment ◽  
Depth Range ◽  
Strength Performance ◽  
Field Development ◽  
Steel Catenary Risers ◽  
Riser Design ◽  
Design Guidance

Deep draft production semi-submersible with steel lazy wave risers (SLWRs) has been studied for the 2,625ft water depth in harsh environment. The design challenges and feasibility of steel catenary risers (SCRs) for semi-submersible at relatively shallow water and harsh environment are discussed. The benefits of using SLWRs to improve riser strength and fatigue performance are presented. Due to the complexity of SLWR geometry, a systematic configuration approach is introduced to achieve the desired riser performance target. A comparison study on fatigue and strength performance of various riser configurations is performed. The assessment provides design guidance for the optimal solution of the integrated hull, mooring and riser system. It concludes that deep draft production semi-submersible with SLWRs can be a feasible and cost effective solution for field development at water depth range from 2,297ft to 3,281ft in harsh environment.

scholarly journals Kicking the OPEC Habit

2000 ◽  
Vol 122 (05) ◽  
pp. 44-51
Author(s):  
Michael Valenti
Keyword(s):  
Oil And Gas ◽  
Oil Prices ◽  
Floating Platform ◽  
Mooring Lines ◽  
Sea Bed ◽  
Floating System ◽  
Heating Oil ◽  
Offshore Oil And Gas ◽  
Offshore Oil ◽  
And Storage

This article highlights that major offshore oil and gas projects may help North America reduce its dependence on the oil cartel. When members of the Organization of Petroleum Exporting Countries (OPEC) cut their production by 4 million barrels per day from March 1999 to March 2000, they tripled oil prices, from $11 to $33 per barrel. The combination of higher gasoline, diesel, and heating oil prices led President Clinton and Congress to pressure the OPEC countries to increase their production. Spar technology has been used for 25 years for loading buoys and storage vessels. The spar is a floating system, basically a cylinder on end that maintains its position with mooring lines sunk into the seabed. Many offshore oilfields are beyond the reach of underwater pipelines. This is an opportunity seized by SOFEC Inc. in Houston. Since 1972, the company, a subsidiary of the FMC Corp., has designed equipment to support floating production storage and offloading systems. These systems consist of a floating platform, basically a moored ship-shaped vessel, equipped to accept oil and gas from a drilling system on the sea bed.

Sand Free Production Success Through Proven Technology Enabler from An Untapped Heterogeneous Reservoir Zone Utilizing Gravel Pack Replacement Methodology

2020 ◽  
Author(s):  
Y. Anggoro
Keyword(s):  
Oil And Gas ◽  
Erosion Resistance ◽  
Cost Effective ◽  
High Rate ◽  
Screen Design ◽  
Sand Control ◽  
Rules Of Thumb ◽  
Production Success ◽  
Control Technologies ◽  
Gravel Pack

The Belida field is an offshore field located in Block B of Indonesia’s South Natuna Sea. This field was discovered in 1989. Both oil and gas bearing reservoirs are present in the Belida field in the Miocene Arang, Udang and Intra Barat Formations. Within the middle Arang Formation, there are three gas pay zones informally referred to as Beta, Gamma and Delta. These sand zones are thin pay zones which need to be carefully planned and economically exploited. Due to the nature of the reservoir, sand production is a challenge and requires downhole sand control. A key challenge for sand control equipment in this application is erosion resistance without inhibiting productivity as high gas rates and associated high flow velocity is expected from the zones, which is known to have caused sand control failure. To help achieve a cost-effective and easily planned deployment solution to produce hydrocarbons, a rigless deployment is the preferred method to deploy downhole sand control. PSD analysis from the reservoir zone suggested from ‘Industry Rules of Thumb’ a conventional gravel pack deployment as a means of downhole sand control. However, based on review of newer globally proven sand control technologies since adoption of these ‘Industry Rules of Thumb’, a cost-effective solution could be considered and implemented utilizing Ceramic Sand Screen technology. This paper will discuss the successful application at Block B, Natuna Sea using Ceramic Sand Screens as a rigless intervention solution addressing the erosion / hot spotting challenges in these high rate production zones. The erosion resistance of the Ceramic Sand Screen design allows a deployment methodology directly adjacent to the perforated interval to resist against premature loss of sand control. The robust ceramic screen design gave the flexibility required to develop a cost-effective lower completion deployment methodology both from a challenging make up in the well due to a restrictive lubricator length to the tractor conveyancing in the well to land out at the desired set depth covering the producing zone. The paper will overview the success of multi-service and product supply co-operation adopting technology enablers to challenge ‘Industry Rules of Thumb’ replaced by rigless reasoning as a standard well intervention downhole sand control solution where Medco E&P Natuna Ltd. (Medco E&P) faces sand control challenges in their high deviation, sidetracked well stock. The paper draws final attention to the hydrocarbon performance gain resulting due to the ability for choke free production to allow drawing down the well at higher rates than initially expected from this zone.

scholarly journals ANN-Based Decision Making in Station Keeping for Geotechnical Drilling Vessel

2021 ◽  
Vol 9 (6) ◽  
pp. 596
Author(s):  
Murugan Ramasamy ◽  
Mohammed Abdul Hannan ◽  
Yaseen Adnan Ahmed ◽  
Arun Kr Dev
Keyword(s):  
Decision Making ◽  
Water Depth ◽  
Business Models ◽  
Cost Benefit ◽  
Cost Effective ◽  
Station Keeping ◽  
Operational Information ◽  
Effective Option ◽  
The Cost ◽  
Cost Factors

Offshore vessels (OVs) often require precise station-keeping and some vessels, for example, vessels involved in geotechnical drilling, generally use Spread Mooring (SM) or Dynamic Positioning (DP) systems. Most of these vessels are equipped with both systems to cover all ranges of water depths. However, determining which system to use for a particular operational scenario depends on many factors and requires significant balancing in terms of cost-benefit. Therefore, this research aims to develop a platform that will determine the cost factors for both the SM and DP station-keeping systems. Operational information and cost data are collected for several field operations, and Artificial Neural Networks (ANN) are trained using those data samples. After that, the trained ANN is used to predict the components of cost for any given environmental situation, fieldwork duration and water depth. Later, the total cost is investigated against water depth for both DP and SM systems to determine the most cost-effective option. The results are validated using two operational scenarios for a specific geotechnical vessel. This decision-making algorithm can be further developed by adding up more operational data for various vessels and can be applied in the development of sustainable decision-making business models for OVs operators.

Qualification and Certification of Polyester Rope for Seabed Contact

2017 ◽  
Author(s):  
Øystein Gabrielsen ◽  
Kjell Larsen
Keyword(s):  
Water Flow ◽  
Water Depth ◽  
Test Method ◽  
Mooring System ◽  
Qualification Test ◽  
Mooring Lines ◽  
Norwegian Sea ◽  
Flow Through ◽  
Full Scale Tests ◽  
Certification Requirements

The Aasta Hansteen spar in the Norwegian Sea is designed to be moored with a taut polyester rope mooring system. The water depth at the field is 1300 meters, and due to the short installation season the most efficient hookup is with pre-installed mooring lines, which require the mooring lines to be laid down on the seabed. DNV certification does not allow seabed contact for polyester ropes unless proven that no soil ingress and damage takes place. To be able to certify the ropes Statoil developed a test method including contact with soil, rope movement and forced water flow through the filter construction. Full scale tests were performed with actual rope and Aasta Hansteen soil, both in laboratory and at site. This paper discusses the certification requirements and presents adequate qualification test together with results from testing.

Pipeline Bundle: A Smart Solution for Infield Transportation—Part 1: Overview and Engineering Design

2009 ◽  
Author(s):  
R. Song ◽  
Z. Kang ◽  
Yuanlong Qin ◽  
Chunrun Li
Keyword(s):  
Engineering Design ◽  
Thermal Performance ◽  
Oil And Gas ◽  
Cost Effective ◽  
Companion Paper ◽  
Transportation Engineering ◽  
Innovative Solution ◽  
Water Pipeline ◽  
Protection Potential ◽  
Offshore Oil And Gas

Pipeline bundle system consisting of carrier pipe, sleeve pipe and internal flowlines offers innovative solution for the infield transportation of oil and gas. Due to its features, pipeline bundle offers a couple of advantages over conventional pipeline in particular for cases where multi-flowlines and high thermal performance are of great interests. The main benefits and advantages of such system include excellent thermal performance to prevent wax formation and hydrates, multiple bundled flowlines, mechanical and corrosion protection, potential reuse, etc. With the developments of offshore oil and gas industries, more and more hydrocarbon resources are being explored and discovered from shallow to deep water. Pipeline bundle system can be a smart solution for certain applications, which can be safe and cost effective solution. The objective of this paper is to overview pipeline bundle technology, outline detailed engineering design issue and procedure. Focus is given to its potential application in offshore for infield transportation. Engineering design principles and procedures for pipeline bundle system has been highlighted. A companion paper addressed the details of the construction and installation of pipeline bundle system. An example is given at the end of this paper to demonstrate the pipeline bundle system concept and its application.

Chemical Deliquification of Unconventional Gas Wells

2014 ◽  
Author(s):  
K.. Francis-LaCroix ◽  
D.. Seetaram
Keyword(s):  
Natural Gas ◽  
Best Practice ◽  
Oil And Gas ◽  
Large Deviation ◽  
Cost Effective ◽  
Gas Production ◽  
Lessons Learned ◽  
Offshore Platforms ◽  
Gas Wells ◽  
Current Production

Abstract Trinidad and Tobago offshore platforms have been producing oil and natural gas for over a century. Current production of over 1500 Bcf of natural gas per year (Administration, 2013) is due to extensive reserves in oil and gas. More than eighteen of these wells are high-producing wells, producing in excess of 150 MMcf per day. Due to their large production rates, these wells utilize unconventionally large tubulars 5- and 7-in. Furthermore, as is inherent with producing gas, there are many challenges with the production. One major challenge occurs when wells become liquid loaded. As gas wells age, they produce more liquids, namely brine and condensate. Depending on flow conditions, the produced liquids can accumulate and induce a hydrostatic head pressure that is too high to be overcome by the flowing gas rates. Applying surfactants that generate foam can facilitate the unloading of these wells and restore gas production. Although the foaming process is very cost effective, its application to high-producing gas wells in Trinidad has always been problematic for the following reasons: Some of these producers are horizontal wells, or wells with large deviation angles.They were completed without pre-installed capillary strings.They are completed with large tubing diameters (5.75 in., 7 in.). Recognizing that the above three factors posed challenges to successful foam applications, major emphasis and research was directed toward this endeavor to realize the buried revenue, i.e., the recovery of the well's potential to produce natural gas. This research can also lead to the application of learnings from the first success to develop treatment for additional wells, which translates to a revenue boost to the client and the Trinidad economy. Successful treatments can also be used as correlations to establish an industry best practice for the treatment of similarly completed wells. This paper will highlight the successes realized from the treatment of three wells. It will also highlight the anomalies encountered during the treatment process, as well as the lessons learned from this treatment.

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