1. Determining permeability cut-off values for net pay study of a low-permeability clastic reservoir: A case study of the Dongying Sag, eastern China.
- Author
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Yang, Tian, Cao, Yingchang, Wang, Yanzhong, Liu, Keyu, He, Chen, and Zhang, Shaomin
- Subjects
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SHALE oils , *PERMEABILITY , *RESERVOIRS , *OPERATING costs , *MERCURY analysis , *WAGES - Abstract
Net pay cut-off values are key parameters in the evaluation of both conventional and unconventional reservoirs. However, there is no widely accepted method for determining net pay cut-off values. The low permeability turbidite reservoirs in the middle part of the third member of the Shahejie Formation (Es3z) in the Dongying Sag are taken as an example; the net pay permeability and porosity cut-off values are determined according to detailed core descriptions, thin section analyses, porosity and permeability test, mercury injection analyses, and well test data. Taking economic benefits into consideration, the concept of a net pay permeability cut-off value refers to the minimum permeability of a clastic reservoir that can produce hydrocarbons and meet the minimum economic benefits under the availability of existing technologies. The proposed methodology of this work is based on balancing the cost and income, and considers related parameters such as the cost of well drilling, investment in surface construction, operational cost, oil price, and oil production. The net pay permeability cut-off values of reservoirs with different thicknesses of development intervals are calculated based on the constraint of the oil price at $50/bbl. Then, the net pay porosity cut-off values are calculated following the pore-throat structure analyses. The proposed method and the net pay permeability and porosity cut-off values for the low permeability reservoirs in this article are acceptable since fit for purpose principle and data available principle have been considered. Meanwhile, this method enables the dynamic evaluation of reservoirs at any burial depth. • The concept of net-pay permeability cutoff in low permeability reservoirs. • The determination method of net-pay permeability cutoff values. • The determination method of net-pay porosity cutoff values. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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