Annulus comprehensive hydraulic equivalent diameter calculation method for irregular borehole section

Abstract

The invention discloses an annulus comprehensive hydraulic equivalent diameter calculation method for an irregular borehole section. The method comprises the steps of acquiring borehole diameter series data and drilling data; calculating the axial length of the irregular borehole section, the length of the well wall curve section and the ratio thereof; monitoring to obtain the sum of flow pressure drops inside and outside the pipe of the irregular borehole section; presetting an annulus hydraulic equivalent diameter, and calculating the sum of internal and external flow pressure drops of thecorresponding pipe; comparing the calculated and monitored flow pressure drops; and when the difference value is not smaller than the preset minimum difference value, adding or subtracting a preset small value to the preset annulus hydraulic equivalent diameter, enabling the difference value to be smaller than the preset minimum difference value by adopting an iterative calculation method, and taking the annulus hydraulic equivalent diameter when the difference value is smaller than the preset minimum difference value as the solved annulus comprehensive hydraulic equivalent diameter. The annulus comprehensive hydraulic equivalent diameter of the irregular borehole section can be rapidly and conveniently determined, the annulus flowing pressure drop calculation performance and convenience are improved, and then the annulus pressure can be accurately and conveniently calculated.

Description

technical field [0001] The invention relates to the technical field of drilling and production engineering well cementing, in particular to a method for calculating the comprehensive hydraulic equivalent diameter of the annular space of an irregular wellbore section. Background technique [0002] Due to the influence of formation heterogeneity, formations at different depths often have different degrees of diameter expansion, and it is very easy to form irregular wellbores such as "candied haws". This kind of irregular wellbore is not convenient to determine the hydraulic equivalent diameter of the annular space, which directly affects the calculation of the annular flow pressure drop. At present, when calculating the flow pressure drop in the annular space, it is assumed that the annular space is a regular smooth vertical wellbore, which is inconsistent with the actual working conditions, resulting in inaccurate calculation of the annular space pressure. Thereby prior art ...

AI Technical Summary

Problems solved by technology

This kind of irregular wellbore is not convenient to determine the hydraulic equivalent diameter of the annular space, which directly affects the calculation of the flow pressure drop in the annular space

At present, when calculating the flow pressure drop in the annular space, it is assumed that the annular space is a regular smooth borehole, which is inconsistent with the actual working conditions, resulting in inaccurate calculation of the annular space pressure

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