Abstract:

The Shiwu oilfield in Songliao basin is a structural lithological hydrocarbon reservoir. There are some kinds of rocks developed in the Yingcheng Formation in Shiwu oilfield, such as sedimentary rock, lava, tuff，sedimentary tuff and tuffaceous sandstone. Each kind of rocks contains a certain amount of volcanic fragments. The content of volcanic material often determines rock type and makes lower reservoir properties.Types of volcanogenic rocks and their identification reflect the characteristics of the source area. Lithologicalidentification with core is accurate, however, the number and distribution of core and drill is limited,which has made it difficult to determine the types of source sedimentary system and its distribution. Lithology identificationusing logging information,especially for volcanic clastic rocks,can make up for the lithological identification restrictions caused by inadequate coring. Lithology identification is carried out by comparison of Potassium logging content of rocks in the different layer, the logging parameter crossplot of Uranium,Thorium of rocks in the same layer,the rose diagram of logging curves of GR, DEN, CNL, AC, R_t,R_MSFL and the crossplot diagram of GR-PE, GR-DEN. Lithology identification of volcano-related rocks has been done effectively and the logging recognition pattern has been established in member Ⅳ-Ⅴof the Yingcheng Formation in Shiwu oilfield.The combination of lithology identification using logging and core has made 5 kinds of rocks types be determined，and the existence and distribution of sediments system are dominated by volcanic provenance，the normal clastic provenance derived from recycled sediments，affected by granite，affected by granite and volcanic rocks together，and mixed provenance in Member Ⅳ-Ⅴ of Yingcheng Formation in Shiwu oilfield.

Key words: Shiwu oilfield, Yingcheng Formation, pyroclastic rock, clastic rock, logging response, identification model, petroleum deposits