Judging and identifying method of drilling oil layer under condition of oil-emulsion drilling fluids

Abstract

The invention discloses a judging and identifying method of a drilling oil layer under the condition of oil-emulsion drilling fluids. The judging and identifying method comprises the steps of extracting the drilling fluids corresponding to various well depths, conducting T1-T2 two-dimensional nuclear magnetic resonance analysis on the extracted drilling fluids, determining the areas of oil peaks of the drilling fluids corresponding to various well depths, determining the masses of crude oils corresponding to various well depths based on a curve of the relationship between the preset crude oilmass and the oil peak area according to the areas of the oil peaks of the drilling fluids corresponding to various well depths, and judging whether or not an oil layer is encountered during drilling according to the masses of the crude oils corresponding to various well depths. The judging and identifying method adopts T1-T2 two-dimensional nuclear magnetic resonance to judge and identify the oillayer which is encountered during drilling under the condition of the oil-emulsion drilling fluids, no relaxation agents are needed, and the oil layer can be accurately identified through single analysis; defects are overcome that it is difficult to judge and identify the oil layer due to adoption of means such as chromatography, fluorescence and pyrolysis and superposition of various information,and cumbersome of secondary analysis caused by the addition of the relaxation agents during one-dimensional nuclear magnetic resonance is removed; by adopting the judging and identifying method, operation is simple in the implementing process, the cost is low, the labor intensity is low, the quantitative degree is high, and the judging and identifying accuracy is high.

Description

technical field [0001] The invention relates to the technical field of petroleum engineering, in particular to a method for identifying an oil layer encountered under the condition of oil-mixed drilling fluid. Background technique [0002] In the process of oil drilling, PDC drill bits are widely used. The cuttings of the PDC bit are in the form of powder, with a large surface area, and are severely scoured by the drilling fluid. The oil content of the cuttings detected on the surface has been greatly reduced. Therefore, the mud logging method based on the detection of the oil content of the cuttings has lost its material basis. If it becomes invalid, it is necessary to detect the oiliness of the drilling fluid in order to detect and accurately evaluate the oil layer in time. However, detection methods such as chromatography, fluorescence, and pyrolysis are greatly affected by oil-mixed drilling fluids, and it is difficult to distinguish artificially mixed oil from formatio...

AI Technical Summary

Problems solved by technology

However, detection methods such as chromatography, fluorescence, and pyrolysis are greatly affected by oil-contaminated drilling fluids, and it is difficult to distinguish artificially mixed oil from formation-invaded oil, which brings great difficulties to the identification, discovery, and evaluation of oil layers.

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