Jin Qiang*+, Wang Rui*, Zhu Guangyou*, Zeng Yi*, and Rong Qihong**
* Department of Resources, University of Petroleum, Dongying, Shandong, China 257061.
** Dongxin Oil Co. of Shengli Oilfield, Dongying, Shandong, China, 257260.
+Author for correspondence, email: email@example.com
A lacustrine fan covering an area of about 175sq. km has been identified in the Liangjialou area in the SW of the Dongying Depression, a Tertiary non-marine rift basin in eastern China. Fluvial and deltaic sandstones are established reservoir rocks in the basin, and the deep-water sandstones of the fan succession, which are assigned to Member 3 of the lower Tertiary Shahejie Formation, are also thought to have important reservoir potential.
Available data for this study included some 800m of core from 16 wells, well-log data from 426 wells, and 220 km of 3D surveys together with well-test and other production data. From geomorphological reconstructions of the fan, we distinguish first-order (major) fan channels from second-order branched and more distal tip channels. Crevasse splays and overbank shales occur between channels, and sandstone lobes were deposited at channel mouths. Conglomeratic sandstones deposited in major channels are probably the most promising reservoir facies (average porosity c. 20%; average permeability >1D).
Fan construction took place during a single complete cycle of lake level variation which was composed of several sub-cycles. During initial highstand conditions, the fan was dominated by small-scale branched and tip channels and intervening sandy lobes. Fan size increased rapidly during the following lowstand, and then decreased during the ensuing highstand.
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