Fluvio-Lacustrine Sandstone Deposition and Implications for Reservoir Development, Daan Field, Songliao Basin, Peoples Republic of China

John S. Sneider¹, Andrew S. Harper², Liu Zhongtian², Wang Chunguo², and Cao Xiuzhi^2
1 Sneider Exploration, Inc, Kemah, TX
² MI Energy Corp,

Since 2001, MI Energy - PetroChina partnership has drilled 150 wells at Daan Field, Songliao Basin, Jilin Province, P. R. China. The main reservoir objective is the Cretaceous FuYang fluvio-lacustrine sandstones. The reservoir has relatively low porosity (10-18%) and low permeability (<1-30mD), and has dramatic changes in reservoir quality over short lateral distances. Accurately predicting reservoir distribution is crucial for successful field development.

During deposition, FUYang sands were deposited in a half-graben bounded by the Daan Fault to the east. FuYang sands accumulated in north- or northeast-trending depocenters, parallel to the Daan Fault. The graben was inverted during the Tertiary along the Daan Fault forming the Daan Anticline which is the trap for the field.

The FuYang reservoir in the Daan Field area is subdivided into approximately 25 stratigraphic intervals which may contain reservoir quality sandstones. Reservoir sandstones are not developed for each interval at every location in the field. The FuYang reservoir is distributed in a series of north- or northeast-trending sand thicks or “Sweet Spots” that measure about 700m by 3000m and have total pay thicknesses of 10m to 35m. Typical “Sweet Spot” wells have 10 sand zones ranging in thickness from 1m to 10m. Sedimentary facies are fluvial (e.g. channel bars, crevasse splays) to marginal lacustrine (e.g. distributary channels, mouth bars).

The top of the FuYang is marked by an abrupt deepening of the Daan Lake, that corresponds to a Songliao Basin maximum drowning event and deposition of the basin's main source rock.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005