Seismic Sedimentology for High-Resolution Hydrocarbon Reservoir Prediction: A Case Study in Cretaceous Qingshankou Formation, Qijia Area, Songliao Basin, China
Zeng, Hongliu¹; Zhu, Xiaomin²; Zhu, Rukai³; Zhang, Qingshi4
¹BEG, University of Texas at Austin, Austin, TX.
²China Univ of Petroleum, Beijing, China.
³RIPED, PetroChina, Beijing, China.
4Daqing Oilfield Company, Daqing, China.
For over four decades Songliao Basin has been the largest oil producer in China. Entering a matured and advanced exploration stage, geoscientists are increasingly focused on targeting thin (1-10m) and stratigraphic traps for reserve growth. Works on these subtle reservoirs using available well and 3D seismic data are challenging. Multiple lithology types (sandstone, calcareous sandstone, shale, and limestone/marl) coexist in the main exploration interval, Qingshankou Formation, and complex and ambiguous seismic geomorphologic patterns are quite different from those that are more familiar in marine sediments.
This study was aimed at integrating seismic lithology and seismic geomorphology for improved reservoir prediction. A new workflow was employed, which includes such key steps as 90° phasing of wavelet, establishing seismic chronostratigraphic framework, data frequency adjustment, petrophysical analysis, attribute analysis, stratal slicing, and seismic sedimentologic mapping by integrating core description, wireline log facies and stratal slices. Two key research issues are (1) how to recognize relevant seismic signal for identifying the best reservoir among different lithology types, and (2) how to optimize seismic attributes and visualization methods to map depositional systems at high resolution and thin-bed level.
We recognized a total of 8 high-order sequences in 300-350 m thick Qingshankou Formation. Each sequence is composed of a LST at bottom and a HST at top, which are basic mapping units for the study. Core and wireline log analysis revealed fluvial-dominated deltaic facies, including distributary channel, mouth bar, delta-front sand sheet, prodelta, and lake. Vertical stack of alternative LSTs and HSTs explains certain lithology/impedance/amplitude associations for different systems tracts. Channel forms, relative impedance, and fine-scale facies boundaries were interpreted from different seismic attribute displays and were superimposed for comprehensive facies interpretation. In the best cases, sandstones as thin as 1-2 m can be predicted.
AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012