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Overview of Oil & Gas SectorThe following slides are not a tutorial but merely an overview of the various phases involved in an oil & gas development. The major phases are:• Exploration (Survey)• Drilling (Exploration – Development)• Construction (EPIC)• Production (Onshore Refinery)• *De-commissioning

1*Note: This presentation discusses decommissioning of offshore facilities only.

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EXPLORATION – SEISMIC SURVEY

EXPLORATION DRILLING / APPRAISAL DRILLING

CONCEPT - FEED

CONSTRUCTION PHASE - Detailed Design, Procurement, Fabrication

CONSTRUCTION PHASE – Transportation, Installation, Hook-up and Commissioning.

PRODUCTION/PROCESSING/ EXPORTING PHASE

Decommissioning of offshore Facility:Basic steps include: - Engineering and Planning; - Permits and Regulatory Compliance; - Platform Preparation; - Well Plugging and Abandonment; - Conductor Removal; - Mobilization of Decommissiong Vessel; - Topsides Removal; - Jacket Removal;- Pipeline and Umbilicals Decommissioning; - Materials Disposal; - Site Clearance and Restoration.

CONSTRUCTION PHASE -Subsea Pipeline to Onshore Refinery

THE PHASES

WHEN THE RESERVOIR IS DEPLETED, THE FACILITIES MUST BE DECOMMISSIONED.

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EXPLORATION – SEISMIC SURVEYS

The Purpose of Seismic Surveys: Seismic surveys are conducted for a variety of reasons. One of the most common uses of seismic data is in connection with the exploration, development, and production of oil & gas reserves to map potential and known hydrocarbon-bearing formations and the geologic structures that surround them. Oil & gas exploration and production is conducted in many places on the earth’s surface, in both the onshore (land) and offshore (marine) domains. In most marine work, the sensor is a hydrophone that detects the pressure fluctuations in the water caused by the reflected sound waves. The cable containing the hydrophones, called a streamer, is towed or ‘streamed’ behind a moving vessel.

3Source: International Association of Geophysical Contractors

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DRILLINGExploration wells are drilled:• To find oil or gas;• To find a new reservoir in a known field;• To extend the limit of a known oil or gas reservoir.

Appraisal wells:Appraisal wells* are drilled after the discovery of oil or gas to establish the limits of the reservoir, the productivity of wells in it and the properties of the oil or gas. If promising amounts of oil or gas are confirmed during the exploration phase, field appraisal is used to establish the size and characteristics of the discovery and to provide technical information to determine the optimum method for recovery of the oil and gas.*Also known as ‘development’ wells. 4

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DEVELOPMENT PLANNING

Development PlanningIf appraisal wells show the reservoir to be technically and commercially viable, the Oil Company will produce a development plan which will be submitted to the relevant authorities. This development plan will include an assessment of potential risks and long term environmental impacts. The plan should also detail projected benefits to local communities (e.g. employment and trade opportunities), as well as proposing how other potential impacts will be managed (e.g. transportation of heavy materials and equipment and an incursion of workers from outside the local community).

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FEEDFEED (Front End Engineering Design) is engineering which may be conducted during Appraisal Drilling and after a Client Feasibility Study, this includes:Basic Engineering Package (BEP)• Major design philosophy• Codes / standards • PID development• Equipment spec/layoutFront End Loading (FEL) • Optimum technology• Value engineering• HAZOP (Safety)• Design to purpose• Constructability• Maintainability• Process simplification and reliability (Quality)• Cost Estimating• Cost / Risk methodology• Vendor information

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Source: INTECSEA (UK) Ltd

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Fabrication of an offshore Jacket and Deck (animation).

https://youtu.be/zwlvRA0zfLI Subject: 3D-Technical Animation for fabricating an Offshore Oil Process Platform – 5.08 mins

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DECOMMISIONING AN OFFSHORE TOPSIDES (One concept, other methods to be discussed).

https://youtu.be/hsj-qWCUU4sSubject: Film and animation – 3 mins 15 secs

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