Characteristics of the Ma-5₄¹ carbonate reservoirs in northern Jingbian Gas Field,Ordos basin

The Ma-5₄¹ carbonate reservoirs in northern Jingbian Gas Field,Ordos Basin are explored in detail on the basis of cores,cast sections and physical properties of the carbonate reservoirs.These carbonate reservoirs contain intercrystal pores,solution openings and microcracks,indicating a kind of low-porosity and low-permeability reservoirs.The solution is thought to be decisive of the reservoir development.The Ma-5₄¹ carbonate reservoirs may be classified into four categories,of which Types I and II are assigned to the high-quality reservoirs in the western and northern parts of the study area.