Relationships between geology and logging/seismic responses were established for the study of diabase from Eastern Sag in Liaohe Basin based on 3 555 m logging intervals and core

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cuttings of diabase from 41 wells and 560 km

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3D seismic data and observation of 86 thin sections acquired in the area.We investigated the lithology

lithofacies and logging identification features of the diabase

performed well data constraining-seismic mapping

and explored the spatial distribution and hydrocarbon accumulation regularity of the rock.Diabase has wholly crystalline porphyric-like texture with phenocrysts of plagioclase and clinopyroxene.The effective reservoir space in the rocks is mainly secondary dissolved pores and fractures.Diabase can be divided into two sub-facies:centrality and border.High-quality reservoirs are inclined to be distributed in border sub-facies.The rocks display themselves as smooth or slight sawtooth logs with high resistivity and low interval transit time

and seismic reflectance signatures of high amplitude

middle- to low-frequency and fine continuity of events.Vertically

the diabase was shown to be mainly distributed in the first and third members of the Shahejie Formation.The rock shows two kinds of original invasion occurrence

namely layer-parallel and translayer invasion and two types of later transformation

i.e.saucer-shaped and fault-block transformation.Distribution of the diabase was mainly controlled by the main strike-slip fault (Jiazhangsi fault and Jiadong fault) of two intrusive manners associated with faulting of unilateral and bilateral invasion.The invasion distance were measured to be 1 375 m to 5 625 m and averaged at 2 572 m and thickness of the intrusions was 49 m to 165 m (averaged 112 m).Generally

larger volume of diabase means larger thickness of overlying strata.The intrusive age of diabase is dated back to late Dongying period as the result of volcanic-hydrothermal effects.Secondary pores caused by fluid-rock interaction is suggested to be a critical factor for the formation of diabase reservoirs and “interface reservoirs” is proposed to be the main reservoiring pattern of the rock.