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titleDerivation


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For the finite-volume reservoir 

LaTeX Math Inline
body V_{\phi,1} \leq V_{\phi,2} < \infty
 the DTR and CTR are both going through the PSS flow regime at late transient times:


LaTeX Math Block
anchorCase2_PSS_p11
alignmentleft
p_{u,\rm 11}(t \rightarrow \infty) \rightarrow \frac{t}{c_t V_{\phi, 1}}



LaTeX Math Block
anchorCase2_PSS_p21
alignmentleft
p_{u,\rm 21}(t \rightarrow \infty) \rightarrow \frac{t}{c_t V_{\phi,2}}


where

LaTeX Math Inline
bodyc_t

average drain-area  total compressibility of formation within  

LaTeX Math Inline
bodyV_{\phi,1}
 which is jointly drained by  producer W1 and injector W2 

Substituting 

LaTeX Math Block Reference
anchorCase2_PSS_p11
 and 
LaTeX Math Block Reference
anchorCase2_PSS_p21
 in 
LaTeX Math Block Reference
anchorCase2
 one arrives to
LaTeX Math Block Reference
anchorCase2_PSS
.



In case when injector W2 supports only one producer W1 both wells drain the same volume and 

LaTeX Math Inline
bodyV_{\phi, 2} = V_{\phi, 1}
 so that 
LaTeX Math Block Reference
anchorCase2_PSS
 leads to:

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which means that producer W1 with constant BHP and finite-reservoir volume will eventually vary its rate at the same volume as injector W2.

In case injector W2 supports many producers {W1 .. WN } then total injection shares towards producers is going to be unit:

LaTeX Math Block
anchorM1IXB
alignmentleft
\sum_k f_{2k} = 1

unless there is thief injection outside the drain area of all producers. 



If pressure in producer W1 is supported by several injectors 

LaTeX Math Inline
bodyN_{\rm inj} > 1
then over a long period of time one can assume:

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