Field A is a significant contributor within the Kaombo development project, offshore Angola. The field comprises five stacked sedimentary units (A1 through A5, from top to bottom) requiring openhole gravel packs (OHGP) as the sand control technique, and a commingle strategy was key to reducing well count. Production from reservoir A4 could not be commingled with that from other sedimentary layers due to the risk of asphaltene precipitation, and A3, water bearing in one panel, also required isolation. The openhole mechanical packer (OHMP) with OHGP completion was used in field A to reduce the well count from the originally planned eight oil producers (OP) to six OP; this brought savings in excess of USD 100 million. Well 1 in field A penetrates all five reservoirs; it was successfully completed in December 2016 with two OHMPs isolating reservoir A4. A well in field B was successfully completed in May 2017 with one OHMP to allow future water shutoff (WSO) with potential production acceleration as well as estimated ultimate recovery (EUR) increase of more than one million barrel of oil equivalent (MMboe). Downhole gauge data analysis combined with mass balance indicated that 100% pack efficiency was achieved in both wells with the expected packing sequence in the presence of packers bypassed with shunt tubes.
The OHMP enhances the versatility of OHGP completions with eccentric shunt-tube screen assemblies, which enable applications such as selectivity, zonal isolation, and water shutoff. The robustness of OHGP completions together with the features mentioned earlier will improve the economics for future projects by reducing capital expenditure (capex) and increasing reserves recovery per well. This application was an important contributor to reduce drilling expenditure (drillex) for the Kaombo development project.