This paper provides a discussion of the many points which should be considered when planning the engineering aspects of subsea development wells. The multi-discipline Issues In a subsea project are presented together In order to emphasise the requirement for effective project management and close teamwork. Drilling activities Including well design and rig selection are considered along with downhole completion design. This Includes the differing requirements of exploration wells and development wells with respect to subsequent well utilization. The requirements of the subsea completion, installation equipment and subsea facilities and their Impact on other well design Issues are presented. Recent industry efforts on subsea equipment standardization through API 17D and other North Sea initiatives and the potential for further industry standardisation are discussed. The paper should form a useful reference for those Involved In subsea projects by way of highlighting the Issues which must be considered, without always presenting solutions. Information has been drawn from many references reflecting primarily North Sea operations In addition to the author's own experience.
The Issues presented are arranged under the following seven headings; Exploration and development well design Issues, rig selection, downhole completion, subsea completion, subsea facilities, standardisation and project management. Subsea well production technology is the theme for the paper and it is Intended to compliment Reference 1 which concentrates on drilling related subsea development well Issues. The nature of a subsea development implicitly involves many disciplines and it is essential that from the earl lest planning phase the potentially conflicting requirements of all the disciplines are taken Into account. This paper presents these Issues In order that they can be considered by personnel Involved with subsea projects and together can form a coordinated approach to production technology for subsea development wells.
The suitability of a subsea well for completion is dependent on its nature as an exploration or development well and more specifically on the way the well was planned. This section highlights various key points which, lf considered early in the well design, can help to make the well more suitable for re-entry and completion should it be required.
One of the earliest design decisions for any well is the seabed location. In the case of an exploration well the seabed location re often chosen to be vertically above the target. This is usually no problem, unless other wells have been drilled or are planned close by, in which case future operations may be significantly complicated by overlapping mooring patterns or seabed wellhead obstructions. (Reference 1). As wells become more appraisal rn nature then the seabed location becomes more of an Issue. A decision has to be taken on an optimum location or locations to group wells together In order to avoid the problems mentioned above. If this decision is not taken and wells are drilled individually then the potential savings from being able to reuse existing wells for either a subsea development or a platform development are reduced.
