Title: Formation water geochemistry and the petroleum geological significance in Yanchang Formation of Wuqi Oilfield, Ordos Basin, China

Authors: Xia Wang; Guomin Fu

Addresses: Earth Science and Resources College, Chang'an University, Xi'an 710054, China; Petroleum Engineering and Environmental Engineering College, Yan'an University, Yan'an 716000, China ' Earth Science and Resources College, Chang'an University, Xi'an 710054, China

Abstract: Formation water can evaluate the petroleum preservation conditions and thus can be used to identify hydrocarbon reservoirs. This paper analysed the formation water geochemistry and its relationship with the petroleum distribution in Yanchang Formation of Wuqi Oilfield, Ordos Basin. The formation water shows property of weak acid and high salinity. The ion concentrations are dominated by C1^-, Na⁺, K⁺ and Ca²⁺. The CaCl₂-type water is predominant. The chemical properties here indicate good sealing conditions for petroleum preservation. The high TDS value and the low (Na⁺ /C1^-), (100 × SO₄^2-/Cl^- and ((CO₃^2- + HCO₃^-/CA²⁺) ratios indicate better sealing condition for petroleum preservation. The formation water chemical geochemistry can provide predictions of oil-rich reservoirs. [Received: January 24, 2022, Accepted: June 04, 2022]

Keywords: formation water; water type; salinity; total dissolved solids; TDS; chemical properties; Yanchang Formation; sealing condition; Ordos Basin.

DOI: 10.1504/IJOGCT.2023.127353

International Journal of Oil, Gas and Coal Technology, 2023 Vol.32 No.1, pp.93 - 102

Received: 22 Jan 2022
Accepted: 04 Jun 2022
Published online: 30 Nov 2022 *

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