Download Oil families, oil-source rock correlation and implication for petroleum

Goldschmidt2017 Abstract
Oil families, oil-source rock
correlation and implication for
petroleum systems, Termit Basin,
Niger
BANG LIU1, GUANGYA ZHANG1, FENGJUN MAO1 AND
1
JIGUO LIU
1
Research Institute of Petroleum Exploration and
Development, PetroChina, Beijing, China
(*correspondence: [email protected])
A geochemical study of 65 oil and 597 source rock
samples was conducted to understand the oil families, typles
and distributions of effective source rocks and evaluate the
geographic extent of the petroleum systems in the Termit
Basin. The studied crude oil samples can be group into three
genetic families. Family I contains 97 oil samples from 53
reservoirs covering most part of the basin. The oils in this
family are characterized by relatively low Pr/Ph ratios (0.501.73) and high gammacerane/C30 hopane ratios (0.22-0.58),
indicating the oils are derived from source rocks deposited in
a saline environment with suboxic to anoxic conditions.
Family II consists 6 oil samples from 3 reservoirs in the
northwestern part of the basin. The oils in this family are
characterized by relatively high Pr/Ph ratios (1.75-2.63) and
low gammacerane/C30 hopane ratios (0.11-0.17), indicating
the oils are derived from source rocks deposited in a
freshwater environment with suboxic conditions. Family III
contains 1 oil sample from TKN-1 reservoir in the east side of
the basin. This family of oil display biomarker distribution
similar to family I oils. The oil in this family is characterized
by relatively low Pr/Ph ratios (1.22) and high
gammacerane/C30 hopane ratios (0.50), indicating the oil is
derived from source rocks deposited in a saline environment
with anoxic to suboxic conditions. Oil-source rock
correlation suggests three major source rocks in the Termit
Basin: Upper Cretaceous marine mudstones, Upper
Cretaceous marine-paralic mudstones and Paleogene
lacustrine mudstones. The Upper Cretaceous marine-paralic
source rocks are dominant in the Basin. This work may
provide information on hydrocarbon potential of source rocks,
and correlation of oil families and source rocks, which will be
crucial in understanding the petroleum system of the Termit
Basin and for guiding petroleum resource assessment and
future exploration.