A new down-hole NMR logging tool
- 1. China Oilfield Service Limited, Well-Tech R&D Institutes, Beijing, China
- 2. State Key Laboratory of Petroleum Resource and Prospecting, China University of Petroleum, Beijing, China
We present a new NMR down-hole tool which is named EMRT and specially designed for offshore oil and gas explorations. Static magnetic field with constant gradient and RF pulses with short excitation time are employed to acquire the echo trains with various modified CPMG pulse sequences [1] [2] [3]. The minimal echo spacing is 0.4ms. There are 8 different depths of investigation (DOI) from 5.5cm to 11.5cm, which are determined by 8 different frequencies from 550 kHz to 960 kHz. This apparatus works with the environment of high temperature (170°) and high pressure (140Mpa) in the down-hole environments with thousands of meters from ground surface. The minimal resolution of antenna is 60cm and maximal logging speed is 200 m/h. Different mode have been developed for the measurement of bound water, total porosity, light oil, heavy oil and gas. In addition, we developed a systematical calibration workflow and equipment to ensure that the 1- and 2-dimentional NMR measurements are valid and accurate.
- [1] J.A. Jackson, L.J. Burnett, F. Harmon, (1980), Remote (inside-out) NMR. III. Detection of nuclear magnetic resonance in a remotely produced region of homogeneous magnetic field , Journal of Magnetic Resonance, 411-421
- [2] G. R. Coates, L. Xiao, M. G. Prammer, (1999), NMR logging principles and applications, Gulf Professional Publishing
- [3] L. Xiao, G. Liao, F, Deng, H. Liu, G. Song, M. Li, (2015), Development of an NMR system for down-hole porous rocks, Microporous and Mesoporous Material, 16-20