Stand-Alone Development

  1. Subsea
  2. Production Engineering
  3. Production Facilities


Typical Stand-Alone Field Development
Typical Cluster Wells Concept

Stand alone field development needs to construct a new host platform. Installation of new infrastructure in deep water is exceedingly expensive. Using the existing infrastructure is the first consideration for starting a new development. This includes existing production platforms, pipelines and wells. Following issues are the main considerations for a stand-alone field development:

  • Well groupings. Clustering wells or installing well templates;
  • Optimizing flowline configuration;
  • Pigging requirements;
  • Possible needs for subsea production boosting or pumping as part of the initial development or future needs.


Well grouping scenarios and location should be determined according to the reservoir data and drilling engineering. Types of wells and their locations can be determined once the reservoir is mapped and the number of wells is created according to the reservoir model. Wells are typically grouped as follows:

  • Satellite wells: typically used for small filed development requiring few wells, for example, concept of tie-back to the existing structures;
  • Cluster wells; common concept for a stand-alone field development. Normally there are 3 to 8 subsea Xmas trees located in the surrounding of a central production manifold,
  • Template wells; the subsea wells are grouped closely together. This concept usually utilizes a template in which the well guide bases and the manifold are integrated. Subsea Xmas trees are landed and locked on each slots of the template;
  • Combination of the above.

Classification of Stand-Alone Facilities

The stand-alone facility is a host facility that receives the production from a field.

Typical Host Faculties

The host facility could even be a land based facility receiving production from a subsea tieback to beach. The stand-alone facilities used in subsea field development can be divided into two categories: fixed platforms and floating systems. Bottom of the fixed platform is located on the seabed to support the decks to be fixed above the water surface. The floater systems have to be moored in place with tendons or wire ropes to keep connection with the subsea systems below. Floating systems can be used from 300 m to more than 1500 m water depth. Following are the definitions and main features of the host facilities.

  • Fixed platforms: fixed platforms are built on concrete or steel jackets which are directly anchored on the seabed. Various types of platforms, e.g. concrete caisson, and steel jacket are used for this concept. A jack up platform is also used for the production of oil and gas. Fixed platforms are usually installed in the water depth within 500 m;
  • TLP: tension leg platform (TLP) is a vertically moored floating structure. A group of tethers called “leg” is used to moor the each corners of the floating structure. The lateral movement is allowed, but vertical movement is prevented by the legs. The TLP can be used in the water depth from 300 m to 1500 m. Both dry trees and wet trees can be used for the TLP production system;
  • SPAR: the Spar platform utilize a large-diameter, single vertical cylinder buoy floating on the sea water surface to support the decks. Spars can be used in the water depth around 1500 m;
  • Semi-submersible platforms: Semi-submersible platform can be operated for drilling, subsea equipments installation and oil/gas production.
  • FPSO: a floating vessel for the processing and storage of oil and gas. The FPSO is designed to receive the production oil and gas from nearby platform or subsea production systems. The crude oil can be offloaded onto a tanker or transported through pipelines. Comparison of the wave responses of the floaters are as following:
  • FPSO is very responsive because of large water plane, large surface area (beam seas), and softer restoring force;
  • Semi-submersible has a slow natural period due to softer restoring force, vortex-shedding, shallow drafts increase pitch/roll response;
  • SPAR has a slow natural period due to softer restoring force, vortex shedding, deep draft reduces pitch/roll response;
  • TLP has a short natural period due to highly tensioned tendons and limited water plane;

References

[1] C. Claire, L. Frank, Design Challenges of Deepwater Dry Tree Riser Systems for Different Vessel Types, ISOPE Conference, Cupertino, 2003.

[2] M. Faulk, FMC ManTIS (Manifolds & Tie-in Systems), SUT Subsea Awareness Course, Houston, 2008.

[3] R. Eriksen, et al., Performance Evaluation of Ormen Lange Subsea Compression Concepts, Offshore, May 2006.

[4] CITEPH, Long Tie-Back Development, Saipem, 2008.

[5] R. Sturgis, Floating Production System Review, SUT Subsea Awareness Course, Houston, 2008.

[6] Y. Tang, R. Blais, Z. Schmidt, Transient Dynamic Characteristics of Gas-lift unloading Process, SPE 38814, 1997.

[7] DEEPSTAR, The State of Art of Subsea Processing, Part A, Stress Engineering Services (2003).

[8] P. Lawson, I. Martinez, K. Shirley, Improving Deepwater Production through Subsea ESP Booster Systems, inDepth, The Baker Hughes Technology Magazine, vol. 13 (No 1) (2004).

[9] G. Mogseth, M. Stinessen, Subsea Processing as Field Development Enabler, FMC, Kongsberg Subsea, Deep Offshore Technology Conference and Exhibition, New Orleans, 2004.

[10] S.L. Scott, D. Devegowda, A.M. Martin, Assessment of Subsea Production & Well Systems, Department of Petroleum Engineering, Texas A&M University, Project 424 of MMS, 2004.

[11] International Standards Organization, Petroleum and Natural Gas Industries-Design and Operation of the Subsea Production Systems, Part 1: General Requirements and Recommendations, ISO 13628-1, 2005.

[12] O. Jahnsen, G. Homstvedt, G.I. Olsen, Deepwater Multiphase Pumping System, DOT International Conference & Exhibition, Parc Chanot, France, 2003.


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