Reservoir Evaluation and Development ›› 2018, Vol. 8 ›› Issue (6): 1-6.

• Reservoir Geology • Previous Articles     Next Articles

Research on determination of effective thickness for oil reservoirs with low permeability: A case of Chang-2 reservoir of Ansai oilfield

Wang Xia1,2,Fu Guomin1,Guo Aihua3,Wang Chao3,Sun Xiao4,Jin Xing2   

  1. 1. School of Earth Science and Resources, Chang'an University, Xi'an, Shaanxi 710064, China
    2. School of Petroleum Engineering and Environmental Engineering, Yan'an University, Yan'an, Shaanxi 716000, China
    3. Xingzichuan Oil Production Plant, Yanchang Oilfield Corporation, Yan'an, Shaanxi 717400, China
    4. Research Institute of Shaanxi Yanchang Petroleum(Group) Co., Ltd., Xi'an, Shaanxi 710000, China)
  • Received:2018-02-07 Online:2018-12-26 Published:2018-12-13


The Chang-2 reservoir of Ansai oilfield has the geological characteristics of low porosity, low permeability, fast change of physical properties and strong vertical and horizontal heterogeneity. Based on the ''four properties'' relation of reservoir, we established the minimum standards of effective thickness by using the core analysis, oil test, production dynamics and logging by the way of histogram method and cross plot method. Then we proposed the different types of interlayer logging quantitative identification chart and the elimination criterion of various interlayer on the basis of the semi-quantification and semi-qualitative analysis by many kinds of logging curves. The minimum values were as follows: the oil-bearing property was to see the grease spots; the lithological property was to see the fine-grained sandstone; the physical property were the porosity was more than or equaled to 11.5 % and the permeability was more than or equaled to 0.63×10 -3μm 2; the electrical property were the resistivity was more than or equaled to 13 Ω·m and the acoustic was more than or equaled to 230 μs/m. The main types of interlayer were calcareous interlayer and muddy interlayer. We could identify and eliminate the interlayer by the quantification of curves of natural gamma, acoustic and microelectrode, and the qualitative analysis of the curves of spontaneous potential, RILD, RILM, microsphere resistivity and micronormal.

Key words: low permeability reservoir, effective thickness, cutoff standards, interlayer elimination, Ansai oilfield

CLC Number: 

  • TE122