Abstract:

The sequence stratigraphic framework and classify sedimentary facies of Xishanyao Formation are established by the basic principles and technical methods of sequence stratigraphy in Shanle oilfield. On the basis, the distribution characteristics of sandstone and the rules of hydrocarbon accumulation within the sequence stratigraphic framework are analyzed and the lithologic reservoir’s types and distribution are predicted. The results show that: Xishanyao Formation experienced an integral cycle of transgression-regression, and Xishanyao Formation is a third-order sequence, which contains two fourth-order sequences. The formation consists of delta front deposition in lowstand system tract, delta plain deposition in transgressive system tract and lacustrine fine sediments in highstand system tract. In the study area lithologic updip pinch out traps can be found in the increasing base level cycle, and sand lens lithologic traps can be sought on the descending base level cycle. Respectively, the delta channel sand in the first and second fragments of the Xishanyao Formation can form the updip pinch out reservoirs under the affect of the later tectonic movements; and the lacustrine turbidite sand body in the third and fourth fragments of the Xishanyao Formation can form sand lens lithologic reservoirs.

Key words: sequence stratigraphic framework, petroleum gas, Shanle oilfield, Xishanyao Formation