True Zonal Isolation in Openhole Alternate Path Gravel Pack Completions

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.

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Water Shut Offs in Two Openhole Gravel Pack Wells, Deepwater Angola

Carragher¹,

Bedouet²,

Talapatra³

et al. 2018

Day 2 Tue, September 25, 2018

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Achieving water shut-off in gravel packed wells is challenging, particularly being able to place a mechanical barrier to flow into a gravel packed annulus. Gravel packed wells, often in deepwater environments, are often high rate wells and interventions can be costly, therefore only techniques with a high probability of success are typically sanctioned. Many gravel pack wells are completed in multiple sands. If there are barriers between the sands that are believed to be laterally extensive, and if water is entering the lower sand, then isolating the lower sand can be a cost-effective intervention. Deepwater wells in Angola were reviewed as to whether a chemical solution or a mechanical solution would be preferred. Providing a suitable mechanical methodology could be developed, it was felt this would provide a preferred solution. Further criteria for applying a mechanical solution were developed, to increase the chances of success. Extensive well modelling was also conducted to identify an optimum set of plugs to be placed in the well. The operator identified a company that had an emerging technology that could offer such a solution. They then worked together to mature the technology through a series of proof-of-concept tests, through trials in Alaska, an early application in a deepwater well in the Gulf of Mexico, followed by a series of qualification tests to be ready for application in Angola. The qualification tests considered not only the mechanical configuration of the wells, but temperature, pressure and wellbore deviation. The application would require placement using a tractor, therefore testing with connecting to the relevant equipment was also incorporated in the plans for the wells. Using a deepwater rig, several plugs were run in each well, including a meltable alloy plug. The latter plug provided a barrier to flow in both the annulus and inside the sand screens. Although not providing a barrier to shunt tubes, extensive modelling work at Cambridge university showed that it was possible to influence gravel movement in the annulus and shunt tubes, so as to maximise the pressure loss. Two wells have had plugging systems run. The first well has reduced water cut from 100% to ca. 40% and shown a significant oil rate benefit. The second well has also shown a reduced water cut (from 70% to 40%).

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True Zonal Isolation in Openhole Alternate Path Gravel Pack Completions

Cited by 9 publications

References 5 publications

Technology Innovation and Integration Enabling More Flexible, Adaptive, and Reliable Sand Control in Openhole Completions

Technology Innovation and Integration Enabling More Flexible, Adaptive, and Reliable Sand Control in Openhole Completions

Openhole Mechanical Packer with Eccentric Shunt-Tube Gravel Pack Assembly Reduces Capex and Accelerates Production in Kaombo Deepwater Development, Angola

Water Shut Offs in Two Openhole Gravel Pack Wells, Deepwater Angola

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