Technical Paper

Ultra-deep and Ultra-safe: Combining Facies Predictions and PPFG Well Planning for the Ultra-Deep water Ayame-1X Exploration Well, Côte d’Ivoire

Written by: Alex Edwards, Par Malmborg, Will Parsons, Andrew Enfield-Kirk, Neil Whitfield, Jeremy Neep, and Kester Waters

This technical paper, entitled: Ultra-deep and Ultra-safe: Combining Facies Predictions and PPFG Well Planning for the Ultra-Deep water Ayame-1X Exploration Well, Côte d’Ivoire” was prepared for the PESGB in 2017.

In May 2017 Ophir Energy announced that the ultra-deep water Ayame-1X exploration well had reached its total depth of 5394m TVDss. The well targeted multiple Cretaceous turbidite channel and fan complexes which were encountered as prognosed. Furthermore, the well drilled and successfully cased the longest riser-less surface section in the region and reached total depth in the subsequent open hole section with a single bit run, again, another basin first. From a pressure perspective the well was drilled safely and the pore pressure and fracture gradient were accurately predicted pre-drill.

Although detailed analysis of the work is still ongoing, we present the workflow that enabled a robust pre-drill pore pressure model to be derived. The pre-drill model utilised lithofacies estimates derived through seismic inversion combined with a thorough assessment of local and regional pressure regimes in order to fully capture and quantify uncertainty. The pre-drill estimates of lithology and pressure were subsequently validated during and after the drilling of the wildcat exploration well.