Experimental investigation of multi-phase flow in an annulus using electric resistance tomography

The hole cleaning is considered a key element of drilling operation as it impacts the economics of drilling operations, operational time of operations and the safety of operations. Inadequate hole cleaning can lead to blockages resulting in loss of circulation and premature wear out of the drill pipe. The transport of solids cuttings as a multiphase flow offers a solution to the hole cleaning issue, as it can aid to lower operational cost, reduce operation time, and enhance the quality of overall drilling operations. Electrical resistance tomography (ERT) is a promising technology to visualize the 3D flow conditions involved in the hole cleaning process. ERT system is utilized to study and analyze the multiphase flow behavior and to provide in situ volume fraction distribution quantitatively through the drilling annulus. The motive of this work is to investigate the effect of different eccentricities (0-50 %), inner pipe rotation speed (0-120 RPM) and liquid flow rates (160-190 Kg/min) on the secondary phase (solids + air) transport across the annulus using the ERT system. The three-phase flow conditions (water, air, and solids) experiments were conducted in the horizontal flow loop with annulus at Texas A&M University at Qatar (TAMUQ) using ERT system. The flow loop annulus line consists of 6.16 m horizontal/inclined line. The inner diameter of the outer acrylic pipe and the outer diameter of the inner stainless steel pipe were 114.3 mm (4.5 in) and 63.5 mm (2.5 in), respectively. The glass beads (2-3 mm) were injected at a concentration of 5 wt%. The experimental results indicate that the ERT sensors have the capability of providing real-time quantitative images of annular multiphase flow regimes and it can be utilized effectively to observe the secondary phase (solids + air) transport across the opaque region of the annulus. It was also observed that the concentration of secondary phase (solids + air) tends to increase with an increase in the eccentricity of the inner pipe and the inner pipe rotation does not have a significant effect on the concentration of secondary phase (solids + air) at selected experimental conditions.