Cuttings Transport Models and Experimental Visualization of Underbalanced Horizontal Drilling

Table 2

Calculation results in different injecting volumes of gas and liquid (immovability).

Liquid injection (l/s)	Gas injection (m^3/h)	Model mixing speed (bottom) (m/s)	Critical mixing speed (bottom) (m/s)	Error between model and real (%)
0.87	90	0.99	1.29	30.2%
1.3	115	1.28	1.59	24.5%
1.86	130	1.46	1.73	18.6%
2.17	150	1.67	1.91	14.4%
2.6	170	1.88	2.11	12.5%
3.25	190	2.09	2.28	9.3%
Average error				18.3%

In Table 2 the critical flow speed refers to the minimum mixing speed when cuttings start to saltate. In the condition attaining to the critical carrying cuttings, comparing the speed calculated by multiphase flow simulation software with the real mixing speed of gas-liquid two-phase flow, the error is concluded and then the current carrying cuttings model is modified.