In recent years improvements in drilling techniques have led to increasingly complex wellbores. These complex wellbores are primarily intended to provide savings on total drilling and completion costs. Highly deviated and horizontal wells and multi-lateral completions offer greatly improved formation access whilst minimising the capital investment costs One of the major disadvantages of the complex wellbore designs is the risky and expensive well interventions necessary for the control of the different payzones. In order to overcome the costly intervention tasks and further allow optimisation of the production process, the industry has universally accepted and promoted the concept of the ‘intelligent well’ This paper not only looks at the driving forces for the intelligent well, but reviews the technologies currently being employed, and further, proposes the areas of research and development required for future intelligent wells


Drilling and completing multiple lateral sections from a common borehole is gaining technical acceptance due to the recent gains and successes made by the drilling companies. As a result, more reservoir planning teams are basing their development scenarios on the completion of wells with multiple laterals In effect, multi-lateral wells are set to become a major feature of fields being developed over the next five years in order to optimise production Add to this the fact that horizontal drilling technology has been fully evaluated and accepted by almost all operators and service companies and we begin to set the background to the growing demand for intelligent completions

Most of today's oil production practices with regard to extraction and reservoir management are based on the measurement of pressure and temperature at the wellhead and at a single bottom hole location The data from the bottom hole (or down hole) sensor is crucial to the production engineers since it allows for the assessment of the field production mechanisms, as well as for a determination of the reserves and in-place volumes

1.1 Multilateral and Multiple Zone Wells (see Figures 1 and 2)

For isolation or control of multilateral or multiple zone wells, it has been necessary to install annular isolation sleeves which have to be operated mechanically - i e either via wireline or coiled tubing This has generally been viable for land-based or offshore (platform) wells where work-over costs are limited to a few thousand pounds per intervention However, for subsea wells, due to vessel costs, interventions can run into the hundreds of thousands of pounds For this reason alone, operation of isolation sleeves is generally limited to coincide with other work-over operations As a consequence, mechanical control of sleeves in subsea wells cannot be considered suitable for ‘active’ well management, where the production from any given well is optimised on a regular basis through the use of downhole flow control equipment

1.2 Production from a Multilateral

Currently, lateral selection options are limited - high costs of well intervention and lost production time means, especially for subsea wells, the primary lateral is normally completely depleted before opening others Simultaneously producing all laterals is only possible when they are at equal pressures, or the wells are completed as dual- or triple-string completions High packer and tubing costs normally prevent such complex completions.

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