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Consider a well-reservoir system consisting of:

  • producing well W1 draining the reservoir volume
    LaTeX Math Inline
    bodyV_{\phi, 1}
  • water injecting well W2 supporting pressure in reservoir volume
    LaTeX Math Inline
    bodyV_{\phi, 2}
     which includes the drainage volume 
    LaTeX Math Inline
    bodyV_{\phi, 1}
     of producer W1 and potentially other producers. 

The drainage volume difference

LaTeX Math Inline
body\delta V_{\phi} = V_{\phi, 2} - V_{\phi, 1} >0
 may be related to the fact that water injection W2 is shared between
LaTeX Math Inline
bodyV_{\phi, 1}
 and another reservoir   or with another producer. 

Case #1 –  Constant flowrate production 
LaTeX Math Inline
bodyq_1 = \rm const >0


The pressure response 

LaTeX Math Inline
body\delta p_1
in producer W1 to the flowrate variation 
LaTeX Math Inline
body\delta q_2
 in injector W2:

LaTeX Math Block
anchorDD4HW
alignmentleft
\delta p_1 = - p_{u,\rm 21}(t) \cdot \delta q_2

where

LaTeX Math Inline
bodyt

time since the water injection rate has changed by the 

LaTeX Math Inline
body\delta q_2
value.

LaTeX Math Inline
bodyp_{u,\rm 21}(t)

cross-well pressure transient response in producer W1 to the unit-rate production in injector W2

Case #2 – Constant BHP 
LaTeX Math Inline
bodyp_1 = \rm const


The flowrate response 

LaTeX Math Inline
body\delta q_1
in producer W1 to the flowrate variation 
LaTeX Math Inline
body\delta q_2
 in injector W2:

LaTeX Math Block
anchor1
alignmentleft
\delta q_1 = - \frac{p_{u,\rm 21}(t)}{p_{u,\rm 11}(t)} \cdot \delta q_2

where

LaTeX Math Inline
bodyt

time since the water injection rate has changed by the 

LaTeX Math Inline
body\delta q_2
value.

LaTeX Math Inline
bodyp_{u,\rm 21}(t)

cross-well pressure transient response (CTR) in producer W1 to the unit-rate production in injector W2

LaTeX Math Inline
bodyp_{u,\rm 11}(t)

drawdown pressure transient response (DTR) in producer W1 to the unit-rate production in the same well



Pseudo-steady state flow

LaTeX Math Block
anchorQ7LHO
alignmentleft
\delta q_1 = -\frac{c_{t,2} V_{\phi, 2}}{c_{t,1} V_{\phi, 1}} \cdot \delta q_2


Steady state flow

LaTeX Math Block
anchorDWLRD
alignmentleft
\delta q_1 = -\frac{c_{t,2} V_{\phi, 2}}{c_{t,1} V_{\phi, 1}} \cdot \delta q_2