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LaTeX Math Inline
bodyN_y

yearsassessment period

LaTeX Math Inline
bodyt

days

running time in the form of the number of days past the start of production 

LaTeX Math Inline
bodyt=0

LaTeX Math Inline
bodyy_t

years

number of whole years past the start of production by the current moment 

LaTeX Math Inline
bodyt

LaTeX Math Inline
bodyr

discount rate





LaTeX Math Inline
body--uriencoded--q%5e%7B\uparrow%7D_%7BO, k%7D(t)

volume/day

oil production rate for 

LaTeX Math Inline
bodyk
-th producer

LaTeX Math Inline
body--uriencoded--C%5e%7B\uparrow%7D_%7BO,k%7D(t)

cash/volume

cost of produced oil treatment and transportation from 

LaTeX Math Inline
bodyk
-th wellhead to CMS CTM

LaTeX Math Inline
bodyR_O(t)

cash/volumeoil selling price

LaTeX Math Inline
body--uriencoded--q%5e%7B\uparrow%7D_%7BG, k%7D(t)

volume/day

gas production rate for 

LaTeX Math Inline
bodyk
-th producer

LaTeX Math Inline
body--uriencoded--C%5e%7B\uparrow%7D_%7BG,k%7D(t)

cash/volume

cost of produced gas treatment and transportation from 

LaTeX Math Inline
bodyk
-th wellhead to CMS to CTM

LaTeX Math Inline
bodyR_G(t)

cash/volumegas selling price

LaTeX Math Inline
body--uriencoded--q%5e%7B\uparrow%7D_%7BW, k%7D(t)

volume/day

water production rate for 

LaTeX Math Inline
bodyk
-th producer

LaTeX Math Inline
body--uriencoded--C%5e%7B\uparrow%7D_%7BW,k%7D(t)

cash/volume

cost of produced water treatment and transportation from 

LaTeX Math Inline
bodyk
-th wellhead to CMS to CTM

LaTeX Math Inline
body--uriencoded--N%5e%7B\uparrow%7D_P(t)

counts

number of producers at 

LaTeX Math Inline
bodyt

LaTeX Math Inline
body--uriencoded--q%5e%7B\uparrow%7D_%7BL, k%7D(t)

volume/day

liquid production rate for 

LaTeX Math Inline
bodyk
-th producer

LaTeX Math Inline
body--uriencoded--C%5e%7B\uparrow%7D_%7BL, k%7D(t)

cash/volume

cost of fluid lift from reservoir to the 

LaTeX Math Inline
bodyk
-th wellhead, cash/volume




LaTeX Math Inline
body--uriencoded--q_%7BWS%7D(t)

volume/day

water supply/disposal rate

LaTeX Math Inline
body--uriencoded--C%5e%7B\uparrow%7D_%7BWS%7D(t)

cash/volumecost of water supply

LaTeX Math Inline
body--uriencoded--C%5e%7B\downarrow%7D_%7BWS%7D(t)

cash/volumecost of water disposal

LaTeX Math Inline
body--uriencoded--q_%7BGS%7D(t)

volume/daygas supply/disposal rate

LaTeX Math Inline
body--uriencoded--C%5e%7B\uparrow%7D_%7BGS%7D(t)

cash/volumecost of gas supply

LaTeX Math Inline
body--uriencoded--C%5e%7B\downarrow%7D_%7BGS%7D(t)

cash/volumecost of gas disposal

LaTeX Math Inline
body--uriencoded--q%5e%7B\downarrow%7D_%7BW, i%7D(t)

volume/day

water injection rate for 

LaTeX Math Inline
bodyi
-th water injector

LaTeX Math Inline
body--uriencoded--C%5e%7B\downarrow%7D_%7BW,i%7D(t)

cash/volume

cost of water injection, including treatment, transportation and pumping into 

LaTeX Math Inline
bodyi
-th well

LaTeX Math Inline
body--uriencoded--N%5e%7B\downarrow%7D_W(t)

counts

number of water injectors at 

LaTeX Math Inline
bodyt

LaTeX Math Inline
body--uriencoded--q%5e%7B\downarrow%7D_%7BG, i%7D(t)

volume/day

gas injection rate for 

LaTeX Math Inline
bodyi
-th gas injector

LaTeX Math Inline
body--uriencoded--C%5e%7B\downarrow%7D_%7BG,j%7D(t)

cash/volume

cost of gas injection, including purchase, treatment, transportation and pumping into 

LaTeX Math Inline
bodyi
-th well

LaTeX Math Inline
body--uriencoded--N%5e%7B\downarrow%7D_G(t)


counts


number of gas injectors at 

LaTeX Math Inline
bodyt

...

The objective function  

LaTeX Math Block Reference
anchorOF
can be rewritten in terms of Surface flowrates 
LaTeX Math Inline
body\{ q^{\uparrow}_L, q^{\downarrow}_W, q^{\downarrow}_G \}
 and usual subject to enginerring engineering restrictions:


LaTeX Math Block
anchorOF_L
alignmentleft
G_t = \sum_{p=1}^{N^{\uparrow}_P} C^{\uparrow}_{OGW}(t)  \cdot q^{\uparrow}_{L, p}(t)
- \sum_{i=1}^{N^{\downarrow}_W} C^{\downarrow}_{W,i} \cdot q^{\downarrow}_{W, i}(t) 
- \sum_{j=1}^{N^{\downarrow}_G} C^{\downarrow}_{G,j} \cdot q^{\downarrow}_{G, j}(t)
- C_{WS} \cdot q_{WS}(t)
- C_{GS} \cdot q_{GS}(t)



LaTeX Math Block
anchorKPBIE
alignmentleft
C^{\uparrow}_{OGW}(t) = \left[  (R_O(t) -  C^{\uparrow}_{O,p}) + (R_G(t) - C^{\uparrow}_{G,p}) \cdot  Y_{gG,p}(t) \right]  \cdot (1- Y_{wW,p}(t)) 
- C^{\uparrow}_{L,p} - C^{\uparrow}_{W,p} \cdot Y_{wW,p}(t) 



LaTeX Math Block
anchorRateLimit
alignmentleft
0 \leq q^{\uparrow}_{L, p}(t) \leq  q^{\uparrow}_{LMAX, p}(t)



LaTeX Math Block
anchorRateLimit
alignmentleft
0 \leq q^{\downarrow}_{W, i}(t) \leq  q^{\downarrow}_{WMAX, i}(t)



LaTeX Math Block
anchorRateLimit
alignmentleft
0 \leq q^{\downarrow}_{G, j}(t) \leq q^{\downarrow}_{GMAX, j}(t)



LaTeX Math Block
anchorRateLimit
alignmentleft
\sum_{p=1}^{N^{\uparrow}_P} q^{\uparrow}_{L, p}(t) \leq q^{\uparrow}_{LMAX}



LaTeX Math Block
anchorRateLimit
alignmentleft
q^{\downarrow}_{WMIN}(t) \leq 
\sum_{i=1}^{N^{\downarrow}_W} q^{\downarrow}_{W, i}(t) 
\leq q^{\downarrow}_{WMAX}



LaTeX Math Block
anchorRateLimit
alignmentleft
\sum_{j=1}^{N^{\downarrow}_G} q^{\downarrow}_{G, j}(t)
\leq q^{\downarrow}_{GMAX}




LaTeX Math Block
anchorRateLimit
alignmentleft
q^{\downarrow}_{WMIN}(t) = \sum_{p=1}^{N^{\uparrow}_P} q^{\uparrow}_{W, p}(t) 



...

LaTeX Math Inline
body--uriencoded--Y_%7Bw%7BW,k%7D(t) = q_%7BW,k%7D / q_%7BL,k%7D

Watercut in 

LaTeX Math Inline
bodyk
-th well

LaTeX Math Inline
body--uriencoded--Y_%7Bg%7BG,k%7D(t) = q_%7BG,k%7D / q_%7BO,k%7D

Gas-Oil Ratio in 

LaTeX Math Inline
bodyk
-th well

...

Expand
titleSandface Formalism



The objective function  

LaTeX Math Block Reference
anchorOF_L
can be further rewritten in terms of Sandface flowrates 
LaTeX Math Inline
body\{ q^{\uparrow}_t, q^{\downarrow}_w, q^{\downarrow}_g \}
:

LaTeX Math Block
anchorG_sf
alignmentleft
G = \sum_{k=1}^{N^{\uparrow}_P} G^{\uparrow}_{t,k} \cdot q^{\uparrow}_{t, k}
- \sum_{i=1}^{N^{\downarrow}_W} G^{\downarrow}_{w,i}  \cdot 
q^{\downarrow}_{w, i}
- \sum_{j=1}^{N^{\downarrow}_G} G^{\downarrow}_{g,j}  \cdot q^{\downarrow}_{g, j} - 
- C_{WS} \cdot q_{WS}(t)
- C_{GS} \cdot q_{GS}(t)
 \rightarrow \rm max


LaTeX Math Block
anchorGtp
alignmentleft
G^{\uparrow}_{t,k} = \frac{\left[  (R_O -  C^{\uparrow}_{O,k}) + (R_G - C^{\uparrow}_{G,k}) \cdot  Y_{gG,k} \right]  \cdot (1- Y_{wW,k}) 
- C^{\uparrow}_{L,k} - C^{\uparrow}_{W,k} \cdot Y_{wW,k} }
{B_{w,k} Y_{wW,k} + \left[ (B_{o,k} - R_{s,k} B_{g,k}) + (B_{g,k} - R_{v,k} B_{o,k}) \, Y_{gG,k} \right] \cdot (1-Y_{w,k})}


LaTeX Math Block
anchorGw
alignmentleft
G^{\downarrow}_{w,i} = B_{w,i} C^{\downarrow}_{W,i} 


LaTeX Math Block
anchorGg
alignmentleft
G^{\downarrow}_{g,i} = B_{g,i} \cdot C^{\downarrow}_{G,i}


where

LaTeX Math Inline
bodyB_{w,k} = B_w(p_{wf,k}(t))

Water FVF for 

LaTeX Math Inline
bodyk
-th well

LaTeX Math Inline
bodyp_{wf,k}(t)

BHPin 

LaTeX Math Inline
bodyk
-th well

LaTeX Math Inline
bodyB_{o,k} = B_o(p_{wf,k}(t))

Oil FVF for 

LaTeX Math Inline
bodyk
-th well

LaTeX Math Inline
bodyR_{s,k} = R_s(p_{wf,k}(t))

 Solution GOR in 

LaTeX Math Inline
bodyk
-th well

LaTeX Math Inline
bodyB_{g,k} = B_g(p_{wf,k}(t))

Gas FVF for 

LaTeX Math Inline
bodyk
-th well

LaTeX Math Inline
bodyR_{v,k} = R_v(p_{wf,k}(t))

 Vaporized Oil Ratio in 

LaTeX Math Inline
bodyk
-th well




Expand
titleDerivation


Panel
borderColorwheat
bgColormintcream
borderWidth7


LaTeX Math Block
anchor427RB
alignmentleft
G(t) = \sum_{p=1}^{N^{\uparrow}_P} \left[ 
(R_O -  C^{\uparrow}_{O,p}) \cdot q^{\uparrow}_{O, p} + (R_G - C^{\uparrow}_{G,p}) \cdot  q^{\uparrow}_{G, p} 
- C^{\uparrow}_{L,p}  - C^{\uparrow}_{W,p} \cdot q^{\uparrow}_{W, p}
\right]  
- \sum_{i=1}^{N^{\downarrow}_W} C^{\downarrow}_{W,j} \cdot q^{\downarrow}_{W, i} 
- \sum_{j=1}^{N^{\downarrow}_G} C^{\downarrow}_{G,j} \cdot q^{\downarrow}_{G, j}


LaTeX Math Block
anchor427RB
alignmentleft
G(t) = \sum_{p=1}^{N^{\uparrow}_P} \left[ 
\left[  (R_O -  C^{\uparrow}_{O,p}) + (R_G - C^{\uparrow}_{G,p}) \cdot  Y_{gG,p} \right]  \cdot q^{\uparrow}_{O, p} 
- C^{\uparrow}_{L,p}  - C^{\uparrow}_{W,p} \cdot Y_{wW,p} \cdot q^{\uparrow}_{L, p}
\right]  
- \sum_{i=1}^{N^{\downarrow}_W} C^{\downarrow}_{W,j} \cdot q^{\downarrow}_{W, i} 
- \sum_{j=1}^{N^{\downarrow}_G} C^{\downarrow}_{G,j} \cdot q^{\downarrow}_{G, j}


LaTeX Math Block
anchor427RB
alignmentleft
G(t) = \sum_{p=1}^{N^{\uparrow}_P} \left[ 
\left[  (R_O -  C^{\uparrow}_{O,p}) + (R_G - C^{\uparrow}_{G,p}) \cdot  Y_{gG,p} \right]  \cdot (1- Y_{wW,p}) 
- C^{\uparrow}_{L,p} - C^{\uparrow}_{W,p} \cdot Y_{w,p} 
\right]  \cdot q^{\uparrow}_{L, p}
- \sum_{i=1}^{N^{\downarrow}_W} C^{\downarrow}_{W,j} \cdot q^{\downarrow}_{W, i} 
- \sum_{j=1}^{N^{\downarrow}_G} C^{\downarrow}_{G,j} \cdot q^{\downarrow}_{G, j}

Translating 

LaTeX Math Inline
bodyq^{\downarrow}_{W, i}
 and 
LaTeX Math Inline
bodyq^{\downarrow}_{G, j}
 to Sandface flowrates 
LaTeX Math Inline
bodyq^{\downarrow}_{w, i}
 and 
LaTeX Math Inline
bodyq^{\downarrow}_{g, j}
 with formation volume factor and substituting liquid production rate 
LaTeX Math Inline
bodyq^{\uparrow}_{L, p}
 from 
LaTeX Math Block Reference
anchorqL
pageLiquid production rate = qL
 one arrives to:

LaTeX Math Block
anchor427RB
alignmentleft
G(t) = \sum_{p=1}^{N^{\uparrow}_P}  \frac{\left[  (R_O -  C^{\uparrow}_{O,p}) + (R_G - C^{\uparrow}_{G,p}) \cdot  Y_{g,p} \right]  \cdot (1- Y_{w,p}) 
- C^{\uparrow}_{L,p} - C^{\uparrow}_{W,p} \cdot Y_{wW,p} }
{B_w Y_{wW,p} + \left[ (B_o - R_s B_g) + (B_g - R_v B_o) \, Y_{gG,p} \right] \cdot (1-Y_{wW,p})}
 
 \cdot q^{\uparrow}_{t, p}
- \sum_{i=1}^{N^{\downarrow}_W} C^{\downarrow}_{W,j} \cdot B_w \cdot q^{\downarrow}_{w, i} 
- \sum_{j=1}^{N^{\downarrow}_G} C^{\downarrow}_{G,j} \cdot B_g \cdot q^{\downarrow}_{g, j}

which is equivalent to 

LaTeX Math Block Reference
anchorG_sf
.






Depending on Lift mechanism the rates in equation 

LaTeX Math Block Reference
anchorG_sf
 may be set directly or calculated from THP and formation pressure 
LaTeX Math Inline
bodyp_e
(which is a usual case in injection wells):

LaTeX Math Block
anchor3WM13
alignmentleft
q^{\uparrow}_{t, k} = J_{t,k} \cdot ( p_{e,k} - p_{wf,k} )


LaTeX Math Block
anchor9HEU2
alignmentleft
q^{\downarrow}_{w,i} = J_{w,i} \cdot ( p_{wf,i} - p_{e,i} )


LaTeX Math Block
anchorFQ5IH
alignmentleft
q^{\downarrow}_{g,i} = J_{g,i} \cdot ( p_{wf,i} - p_{e,i} )


Producing wells may spontaneously vary between Constant rate production: qL = const and Constant pressure production: pwf = const (see Constant rate production: qL = const for alternation details).


...

Constant rate production: qL = const ] [ Constant pressure production: pwf pwf = const ]