Rock Bit Drilling Performance Laboratory Tests Using Vortexx® Nozzles

Borehole and Mud Cake from Standard Jet	Borehole from Vortexx® Jets

These rock samples were drilled in a drilling laboratory using a roller cone bit. The only difference in this controlled test was the jets. The left borehole was produced using three standard jets; the right borehole was produced using three Vortexx^® jets. Note the cleanliness of the Vortexx® borehole and the clear indentations from the cutters illustrating that the bottom of the hole has been effectively cleaned leaving no re-drilled cuttings. In contrast, notice the cake of re-drilled cuttings, removed from the bottom of the borehole after the test with the standard jets, and placed on the top of the rock sample. This illustrates that the standard jets were unable to fully remove cuttings from the bottom of the hole and were consequently re-drilled and remained on the hole bottom. As shown in the final rock sample, the Vortexx^® jets produced no re-drilled cuttings. The bit ID has been covered in this photograph.

Vortexx^® Jet vs. Standard Jet - Rock Bit Laboratory Rate of Penetration (ROP) Test

A 7-7/8 Smith International Incorporated F15H rock bit was tested at the Amoco Drilling Research Laboratory in Tulsa, Oklahoma. The rotating speed was about 80 rpm, while the flow rate was about 323 gpm. Three standard 12/32, circular nozzles were tested against an alternate geometry Vortexx^® model V12CLBA. The weight on bit (WOB) ranged from about 5 to 46, kips. The experimental results were fitted to cubic curves as shown below.

In that case, the ROP enhancement ranged from about 30% on the low end WOB to about 50% near the maximum WOB. While these early ROP improvements from simply changing the nozzle hydraulics are quite impressive, they do not match those enhancements obtained for the PDC bits. The complex geometry of the rock bit, its moving parts, the increased standoff distance, and other factors make the optimization of the Vortexx^® jet geometry for rock bits a slower process.

The continuing CFD parametric studies of the Vortexx^® nozzles for rock bits suggest that additional ROP increases are obtainable. Even so, this test verifies that existing bit designs can yield significant ROP enhancement simply by the addition of Vortexx^® fluted nozzles. The more recent field test data shows even better performance than these lab tests.