Abstract:

After hydrocarbon zone is penetrated, one part of the oil and gas keeps in rock samples, and the other part enters into drilling fluid. There are mud logging methods for measuring oil and gas contents in rock samples, and gas content in drilling fluid. But there is no existing method for measuring oil content in drilling fluid. With the deepening of exploration degree and development of drilling technology, cuttings and gas surveying often have no showings or lower showings.  It therefore has becoming increasingly difficult to find and evaluate hydrocarbon zone. Under such circumstance, it is essential to measure the oil content in drilling fluid. In this work, we used NMR T₂ spectrum to measure the contents of light oil and medium oil, and T₂-D spectrum to measure heavy oil content in drilling fluid. These methods provide valuable complements to the existing mud logging series, and can be used to improve oil layer finding ratio and evaluation precision ratio.

Key words: magnetic resonance, drilling fluid, oil content, detection while drilling, quantitative , evaluation