This paper describes a new economical concept in subsea drilling and completion that has allowed the justification and recent installation of a diver-assist wet subsea tree in the Gulf of Mexico from a jack-up rig. This concept reduces costs on subsea completions and now makes profitable the production of innumerable small reservoirs, production of innumerable small reservoirs, either looked at and counted uneconomical by previous parameters, or yet to be discovered small reservoirs in the marine environment. The simplicity of this concept greatly reduces costs and allows the operator to use the concept on every exploratory well drilled from a jack-up rig.


Many known opportunities exist in the marine environment which have been determined uneconomical by previous parameters, yet they exist around or parameters, yet they exist around or near existing structures. The ability to produce these known opportunities near existing structures with a favorable rate of return can now be done and will add to the worlds total recoverable reserves and produce additional revenue and profit dollars.

Mechanical success has been achieved by the industry in many areas of development, such as completion fluids, perforating techniques, sand control and downhole completion equipment.

In some cases, however, the total economics are still slightly less than desirable. The preferred rate of return, established by a company for each investment, governs the magnitude of development dollars, "Y", available for a hydrocarbon accumulation that has a recoverable reserve value of "X" dollars. Economic parameters are affected by either an increase in product value or a decrease in completion and production costs. production costs. The most significant area of cost savings can exist from the mudline up. Hydrocarbon accumulations found in water depths up to 300' and at shallow formation depths (normal pressure) are not always of the magnitude or in a location that can result in an economical development. Cost factors leading to the branding of such developments as uneconomical were found to be:

  • From an existing structure.

    1. Directional plan not feasible due to the wellbore angle and/or configuration resulting in high mechanical risks and thus costs.

    2. Lack of formation competency adding to the mechanical drilling risks and subsequent costs to complete the high angle well.

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