Sensitivity Analysis of T2-T1 2D NMR Measurement Parameters in Shale Oil Reservoirs

Abstract

In order to improve the reliability of two-dimensional nuclear magnetic resonance (2D NMR) measurement in shale oil reservoirs, the T2-T1 2D NMR response characteristics and influencing factors of shale oil reservoirs were analyzed in three scenarios: laboratory core analysis, wellsite mobile full-diameter core scanning and logging. For different application scenarios, the optimization method of T2-T1 NMR measurement parameters for shale oil reservoirs were proposed. Laboratory core measurements require attention to the choice of echo interval time (TE) and number of echo groups, in addition to the different magnetic field strengths and measurement sequences. When scanning full-diameter cores at the well site, it is necessary to focus on TE and minimum waiting time (Tw). To ensure the convergence in T1 dimension of quickly relaxed component, the minimum Tw should be set to at least 1 ms. NMR logging is limited by the acquisition conditions. It is necessary to focus on the distribution range and smoothing factor in data processing to interpret and modify data with different signal-to-noise ratios. A poor shale oil reservoir with NMR porosity less than 5% is difficult to ensure the accuracy of NMR results for its low signal-to-noise ratio. The systematic analysis of T2-T1 2D NMR measurement parameters provides a reference for the optimization of 2D NMR detection methods for shale oil reservoirs, which helps to improve the accuracy of NMR measurements and obtain more reliable reservoir information.

Keywords

• 2d nmr
• parameter optimization
• t2-t1
• shale oil