A Two-Dimensional NMR Logging Method for Gas-Water Identification in Dolomite Reservoir of the Western Sichuan Gas Field

doi:10.11938/cjmr20192754

Abstract

Abstract: The dolomite reservoirs in the fourth member of Leikoupo formation of the western Sichuan gas field have good prospects for natural gas exploration and development. However, the conventional and one-dimensional nuclear magnetic resonance (1D NMR) logging data are not sufficient for a definitive classification of the reservoir fluid type, likely because of heterogeneity of the reservoirs. Through geological characteristics analysis, log response analysis and two-dimensional (2D) NMR experiment, the environmental factors and technical parameters leading to the differences between the laboratory results and actual logging data were determined. According to the analysis of T₂-T₁ and T₁/T₂ (R) differences, the distribution range of drilling fluid, bound fluid, movable water and natural gas signals in the 2D NMR spectra was delineated to build a gas-water 2D NMR identification chart. The results obtained using the identification chart were verified with the actual drilling test results. Complementary to conventional and 1D NMR logging, the 2D NMR identification method was proposed, and can be used to determine the fluid properties in the dolomite reservoirs effectively.

Key words: low-field NMR, T₂-T₁ logging, western Sichuan gas field, fourth member of Leikoupo formation, dolomite reservoir, gas-water identification

CLC Number:

O482.53

ZHANG Shi-mao, GE Xiang, WANG Xin, HOU Ke-jun. A Two-Dimensional NMR Logging Method for Gas-Water Identification in Dolomite Reservoir of the Western Sichuan Gas Field[J]. Chinese Journal of Magnetic Resonance, 2020, 37(3): 360-369.

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