ABSTRACT

Hydrate management is a major challenge for offshore oil and gas fields, and in subsea pipelines transporting gas from offshore platforms to the onshore processing facilities. This paper is intended to discuss the various hydrate control methods and strategies that have been evaluated and implemented during the project's design, startup, and operation stages to come up with the most efficient and economical solution for hydrate mitigation.

Methanol, MonoEthylene Glycol (MEG) and kinetic hydrate inhibitors (KHIs), as well as Twister Technology, were evaluated to act as hydrate prevention mechanisms. Based on the CAPEX, OPEX and unmanned operation philosophy, KHI was used for hydrate inhibition in the gas Field-A. This paper will discuss different innovative strategies to eliminate hydrates during steady-state and transient operations. It will also consider cold startup, maximum flow and minimum temperature, planned and unplanned shutdowns, depressurization, and purge and pilot gas scenarios.

The optimum hydrate management control for Field-A offshore platforms and subsea pipelines was a combination of different strategies. For the Field-A, KHI and MEG injection were utilized in combination or independently depending on the scenario.

The challenges experienced during the commissioning, startup and operation of the first Saudi Aramco offshore facilities resulted in many potential innovations and patents as follows:

  • Development and installation of the PMS resulted in reducing the operating cost.

  • Development of variable speed pipeline pig technology.

The challenges and lessons learned associated with hydrate management will be discussed in addition to the advantages and disadvantages of the used chemicals.

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