Physical Modeling of Sand Production in Vertical and Horizontal Wells of Underground Gas Storage Facilities Using a True Triaxial Loading Setup

Underground gas storage (UGS) wells are operated in a cyclic mode—bottom hole pressure increase for gas pumping alternate with bottom hole pressure decrease for gas extraction. This can lead to partial destruction of the bottomhole zone of the formation, which is accompanied by sand production. It leads to clogging of filter channels, a decrease in flow rate and wear of underground and surface equipment. The unique facility Triaxial Independent Loading Test System (TILTS) of the Institute for Problems in Mechanics RAS allows to directly simulate the process of pressure reduction at the bottomhole by the so-called scheme “hollow cylinder” on cubic specimens with a 40 mm edge, which made of core material of reservoir. This paper presents the results of an experiments series conducted on the specimens made of core material of the Udmurt UGS. The results of modeling on these specimens on the “hollow cylinder” scheme obtained on the TILTS unit allow us to conclude about the presence of strength anisotropy of reservoir rocks of this UGSF. Modeling of the creation of pressure drawdown in differently oriented wells showed that the destruction of the well walls and sand production in horizontal wells occurs at lower drawdown values and to a greater extent than in vertical wells.