Tight oil play characterisation: the lower–middle Permian Lucaogou Formation in the Jimusar Sag, Junggar Basin, Northwest China. Issue 3 (2nd April 2016) - Hu, T.
ABSTRACT: The lower–middle Permian Lucaogou (P2 l) Formation is a "sandwich-type'' combination of source rocks and reservoirs that is considered to be a potential tight oil reservoir in the Jimusar Sag (JS). We investigated the P2 l Formation using a designated workflow to assess its potential as a viable tight oil reservoir play using geological, petrographical, petrophysical, and geochemical characterisation of core samples. The results showed that the P2 l source rocks have a widespread distribution (up to 1500 km 2 ), a huge thickness (up to 160 m), a relatively high abundance of organic matter (averaging 3.12 wt%), a good sapropelic quality, and a moderate thermal maturity. The reservoir consists mainly of dolomites and siltstones, predominantly characterised by secondary dissolved pores, with medium–high porosity (averaging 9.1%) and relative low permeability (averaging 0.26 mD), high abundance of brittle minerals (averaging 87.1%), and low abundance of clay minerals (averaging 11.2%) with low water sensitivity. The results demonstrate that in the JS area the P2 l Formation has great potential for tight oil production with its considerable hydrocarbon expulsion quantities, good oil storage capability, and reservoir frackability potential and provide a basis for further evaluation of the tight oil potential of the P2 l Formation in the wider Junggar Basin and for identifying similar plays elsewhere.