Abstract

This paper summarises the results of Primeline’s Vicky-1 exploration well (drilled 1997) which tested potentially commercial quantities of hydrocarbons from a new Palaeocene reservoir in the Lishui Sub-basin, East China Sea Basin. This well represents an exploration breakthrough after a sequence of 14 unsuccessful wells drilled by foreign operators on acreage awarded in the First East China Sea Licensing Round in 1993.

The discovery confirmed Primeline’s pre-drilling exploration concept and has established a new hydrocarbon play system which Primeline believes has significant additional exploration potential. The play system is characterised by a sequence of stacked marine sandstone reservoirs which are coincident with mature source rocks and are overlain by good regionally-extensive sealing cap rocks.

Source rocks are interpreted as marine but containing mostly type III kerogen and therefore gas prone. Modelling suggests that the main period of hydrocarbon genesis predates the latest structural phase and therefore points to multiple potential trapping scenarios, both structural and stratigraphic.

The Vicky-1 well tested at a rate of 9.8MMcf/D (0.279×10⁶m³/d) of gas and 117BPD (8.9 m³/d) of hydrocarbon liquids from the topmost part of a reservoir column of several hundred metres gross thickness. “Most Likely” reserves are estimated at 660Bcf (18.7×10⁹m³) with estimated upside including appraisal and nearby-exploration potential of 4.4TCF (125×10⁹m³).

The Marine Palaeocene “play fairway” parallels the coastline’ of China’s most dynamic and energy-hungry provinces and is ideally located to allow commercialisation of even small future reserves additions.