Fracture Enhanced Chalk Matrix Permeability as a Driver for Completion Strategy. Curlew C Field, Block 29/7, UKCNS

The Curlew C field development is an example of unlocking potential within the fractured Upper Cretaceous chalk through integration across subsurface disciplines and using data from LWD and wireline tools to optimise well completion.

The field is developed by a single sub-horizontal well with a 5,000’ producing section, completed across both Tor and Ekofisk formations. An integrated approach to well planning was applied using seismic QI techniques, regional data, analogues and chalk geology and calibrated by the 29/7–5 exploration well.

The CuCP1 well successfully drilled and logged the horizontal reservoir section, including a high-resolution FMI image log. Detailed log evaluation of the well showed the Tor Formation to comprise both allochthonous and autochthonous chalk units.

Fractures are distributed across the whole reservoir, but mainly in the lower porosity formation.

The high degree of fracturing was considered a risk for water production and the well was subsequently completed across the most porous intervals only, with the fractured zones isolated by Expandable Casing Packers.

The Curlew C development has proved to be a success through an integrated approach to target selection and reservoir characterisation for matrix and fracture interaction driving a completion strategy for long-term oil production and water-mitigation.