AVO Research on Coalbed Methane Reservoirs in East Ordos Basin

Zhang, Tieqiang (BGP/CNPC) | Sun, Pengyuan (BGP/CNPC) | Qian, Zhongping (BGP/CNPC) | Ma, Guangkai (BGP/CNPC)

OnePetro 

Abstract

DESCRIPTION: In east Ordos basin, there are plenty of coalbed methane (CBM) resources. However, the coalbeds are of strong heterogeneity due to laterally variant thickness and gas contents. Consequently, the heterogeneity gives rise to the great challenges for fine reservoir prediction and evaluation in seismic exploration. For the purpose of applying AVO to CBM prediction, in this paper, combining with geological and geophysical characteristics of CBM reservoirs NO. 5 coal seams from drilling, logging and the relationship between elastic parameters and gas contents in the lab, we established a set of thin coalbed models with different thickness and gas contents to model AVO using reflectivity method. Subsequently, AVO responses to gas contents and thickness of CBM reservoir are systematically investigated.

APPLICATIONS: Our researches are theoretical discussion about the relationships between AVO responses and coalbed thickness and gas contents. These relationships can be applied to exploration of CBM reservoirs in practice.