Radius of Investigation

By definition:

$$ r = \sqrt{\frac{k t}{\phi \mu c_t}} $$

or in oil field units

$$ r = \sqrt{\frac{k t}{948 \phi \mu c_t}} $$

If \( k = 0.02 \text{mD}\), \( \mu_g = 0.022\text{cP}\), \( c_t = 2 \times 10^{-4} \text{psi}^{-1} \), \( \phi = 0.04 \), then

Setting \( r = 300 \text{m (984.25ft)}\) will give \( t = 8077\text{h}\) or about a year

Setting \( r = 200 \text{m (656.17ft)}\) will give \( t = 3600\text{h}\) or about 0.4 years