Casing/cementing/zonal isolation

Wellhead Design Enables Offline Cementing and a Shift in Operational Efficiency

Offline cementing was used to develop a marginal field in Malaysia. The development was made possible through distinctive wellhead technology and good operational planning.

Offline cementing sequence for 9⅝-in. surface casing.
Fig. 1—Offline cementing sequence for 9⅝-in. surface casing.

Traditionally, rigs are positioned over a well from the moment the surface casing is drilled until the installation of the wellhead tree. This results in the loss of precious time as the rig idles during online cementing. However, in mature Field A offshore Terengganu, Malaysia, a new approach eliminated such inefficiency dramatically.

Operational Planning

With oil production in Field A initiated in October 2015, historical data on well lithology, formation pressure, and potential issues during drilling were available and were studied to ensure that wells would not experience lost circulation. This preplanning is crucial to ensure that the offline cementing activity meets the operator’s barrier requirements.

Petronas Procedures and Guidelines for Upstream Activities (PPGUA 4.0) was used for the development of five subject wells in Field A. In this standard, two well barriers are required during all well activities, including for suspended wells, to prevent uncontrolled outflow from the well to the external environment.

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