A new method for calculating the minimum sand-carrying velocity in geothermal well production

Abstract

Formation sand production is an important engineering and technical problem that restricts the safe and efficient development of geothermal wells. Accurate prediction of the minimum sand carrying velocity of sand production is the key to effectively controlling the formation sand production of geothermal wells. Compared with conventional vertical well sand production, geothermal wellbore sand carrying has the characteristics of high concentration, high fluid temperature, and easy silting, which makes it more difficult to calculate the minimum sand carrying velocity. In order to derive the formula of sand carrying law suitable for complex geothermal conditions, this paper considers the temperature and concentration conditions, based on the basic sedimentation principle and indoor sand carrying experiment, abandons the single correction coefficient correction of the conventional calculation formula, integrates the influence of temperature and high sand content on debris migration and deposition, and adopts the double correction coefficient of temperature-viscosity and sand content-mixed density, the actual minimum sand carrying velocity calculation formula of geothermal well under different sand content and temperature is obtained, and a new theoretical calculation method of minimum sand carrying velocity of the geothermal wellbore is formed. With the help of indoor experiments, a reasonable experimental group was designed to carry sand law experimental research. The experimental results show that the calculated value is in good agreement with the measured data, and can be used to calculate the minimum sand-carrying velocity of unconsolidated sandstone in the geothermal wellbore, which provides a basis for sand-carrying failure and sand sinking prevention in geothermal wellbore site.