Abstract
Conductor sharing allows two or more wells to be drilled from a single drilling slot, expanding well capacity of a platform at minimal cost. As limited slot availability is one of the driving forces behind the selection of multi-lateral wells, conductor sharing is a possible alternative. Experience with both technologies on the Bongkot field has proved that conductor sharing can offer greater operational flexibility than the multilateral alternatives at equivalent costs.
In multi-lateral wells full isolation of the drains requires expensive equipment and complicated procedures. These complexities increase the cost of well construction and increase the risk of partial or complete failure to reach the objectives. With the multi-lateral on production the costs and risks associated with well servicing operations are also higher.
Drains drilled from shared conductors are operated independently during drilling, completion and production phases. Proven technologies can be used at all stages of the well life, minimizing both equipment costs and the risks of failure. Initial well costs are therefore lower while maximizing production flexibility. Well servicing operations are reduced in both frequency and complexity.
To date on the Bongkot field conductor sharing has been used in seven slots for gas producing wells and horizontal oil wells. A multi-lateral well was previously drilled on the field allowing a direct comparison of the two methods. The cost differential of drilling and completing two horizontal wells from a shared conductor and one multi-lateral well was less than 10%.
As a further benefit, the minor initial investment required to convert a slot to a shared slot at the time of the 1st well installation, will in future eliminate the need for costly and risky slot recoveries, in order to tap unproduced reserves reachable from mature fully drilled Work Platforms, hence increasing the amount of recoverable reserves.
The paper describes the principles of the conductor sharing, the perceived advantages over multi-lateral wells and slot recovery, and presents results from multi-lateral, recovered slot and shared conductor wells drilled to date.
