Hence, T can be calculated by


fn r2

or from Figure 9.8.1, T can be obtained by 2,3Q A log r

2k As

Figure 9.7.2 shows that the drawdown between two points s1 — s2 reaches a constant value after a day or two. Therefore, Equation 9.8(3) can be used to determine T before the flow achieves a steady state.

log r

FIG. 9.8.1 Plot of drawdown s versus distance r.

Once T has been calculated, S can be determined with the transient-flow equations, Equations 9.7(14) and 9.7(20), as


22 4Tt

22 4ks


Since T, Q, and s are known for a given r and t, W(u) can be obtained. With the use of Table 9.7.2, the corresponding value of u can be found. S can be calculated from Equation 9.8(6).

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