Int. J. of Oil, Gas and Coal Technology   »   2016 Vol.13, No.4

 

 

Title: The critical porosity of tight sandstone: electrical property change based on pore structure and minerals

 

Authors: Yili Kang; Mingjun Chen; Lijun You; Haitao Zhang; Yu Che

 

Addresses:
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China
National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields, Xi'an 710018, China
State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu 610500, China

 

Abstract: Porosity, which is an important petrophysical parameter of tight sandstone, is closely related to its electrical property under 100% brine saturation. In this work, core resistivity measurements were conducted under reservoir net confining stress with samples from Upper Permian tight sandstone to investigate its critical porosity. Meanwhile, TS, XRD and CEC analyses were implemented. Experimental results show that the change of electrical property with porosity is not clear unless putting 5% as a cut-off point of porosity. It is found that the contribution of brine to core resistivity is variable for different porosity and 5% is the key cut-off point. Considering that core electrical property is determined by pore structure and minerals, microstructure was studied, indicating that 5% is the demarcation point of porosity. Further, mineralogical composition and clay's extra conductivity were analysed, and the results correspond to the conclusion on the porosity of 5% drawn by core resistivity measurements. [Received: October 7, 2014; Accepted: October 3, 2015[

 

Keywords: tight sandstone; core resistivity; porosity; pore structure; clay minerals; petrophysics; electrical properties; brine saturation; reservoir net confining stress; microstructure; clay conductivity.

 

DOI: 10.1504/IJOGCT.2016.10000753

 

Int. J. of Oil, Gas and Coal Technology, 2016 Vol.13, No.4, pp.321 - 337

 

Available online: 19 Oct 2016

 

 

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