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Production Optimization Using Nodal™ AnalysisProblems

“Production Optimization Using Nodal Analysis”

Problems / Exercises

Problems:1.) Oil Completion Problems Problem Section P012.) Gas Completion Problems Problem Section P02

Table Of Contents For

5-1




Problems / Exercises

Problems:

1) Oil Completion Problems

Section: P01

5-2

Exercise: PO2 - Oil Completion Problems

Flowing SIBHP FieldType Of Oil / Cond Gas Producing Initial Water Wellhead Wellhead Reservoir Reservoir Pressure

Reservoir Gravity Gravity G.O.R. BS&W S.G. Temp Pressure Temp Pressure Gradient(o API) (scf/STB) ( % ) (o F) (psia) (o F) (psia) (psi/ft)

oil

Well WellCompletion Completion O.D. O.D.

Depth Depth Tubing Tubing Casing Casing SCSSSV Flowline Flowline Choke Art LiftTVD MD Installed Installed Installed Installed Installed Installed Length Installed Installed(ft) (ft) (in) (ppf) (in) (ppf)

Drilled Drilled WellboreDepth Depth Pipe HydraulicsTVD MD Roughness Correlation(ft) (ft)

( 1 )

( 2 )

( 3 )

Production Optimization Using Nodal Analysis

Producing Reservoir And Fluid Properties Data

Mechanical Completion Design Data

Systems Analysis Required

Available Well Test, Inflow Performance, And Other Well Data

Oil Completion Problem Set

5-3

Exercise: PO2 - 01Inflow Performance And Completion Selection

- A development well was drilled to 10875 ft and plugged back to 10150 ft. The reservoir mid point is at 10000 ft.- A single well test of the reservoir at 10000 ft was obtained: flowing 1250 STBFD at 2150 psia Pwf.- Production engineering has begun evaluation of the mechanical completion.- A Vogel IPR has been chosen for the design analysis.



oil 38 0.65 700 10 1.02 120 140 190 4550 0.455( Pftp )



10000 10000 3-1/2" 9.3 No No No No


10875 10875 0.0018 HagedornBrown

( 1 ) Evaluate the proposal of installing 3-1/2" completion tubing in the well to operate at a Pftp of 140 psia.

( 2 ) Discuss the shapes of the IPR and IPC curves and the meaning of the curve shapes.

( 3 ) Discuss the meaning of the curves intersection point.






5-4

Exercise: PO2 - 02Flowing Tubing Pressure Sensitivity

- Well data is identical to Problem # 01. - A development well was drilled to 10875 ft and plugged back to 10150 ft. The reservoir mid poin tis at 10000 ft.- A single well test of the reservoir at 10000 ft was obtained: flowing 1250 STBFD at 2150 psia Pwf.- Production engineering has begun evaluation of the mechanical completion.- A Vogel IPR has been chosen for the design analysis.



oil 38 0.65 700 10 1.02 120 140 190 4550 0.455( Pftp )



10000 10000 3-1/2" 9.3 No No No No



( 1 ) Shortly after completion, the field engineers need to evaluate a broad range of well performance over a range of Pftp evaluate from 20 psia to 700 psia Pftp (20, 80, 180, 250, 300, 500, 700).

( 2 ) Discuss the shape of the IPC curve at approximately 750 psia Pftp. What is happening?

( 3 ) Construct a plot of Pftp vs flow rate.






5-5

Exercise: PO2 - 03 & 03 A & 03 BFlowing Tubing Pressure And 2-1/2" Flowline Connected

- A development well was drilled to 10445 ft and plugged back to 10150 ft. The reservoir mid point is at 10000 ft.- A single well test of the reservoir at 10000 ft was obtained: flowing 1410 STBFD at 2440 psia Pwf.- Production engineering has begun evaluation of the mechanical completion.- A Vogel IPR has been chosen for the design analysis.



oil 38 0.65 650 10 1.02 120 147 198 4660 0.466



10000 10000 3-1/2" 9.3 No Yes 1000 No No2-1/2" No Elev

Sch. 80 ChangeDrilled Drilled Wellbore FlowlineDepth Depth Pipe Hydraulics Temp

TVD MD Roughness Correlation 80o

(ft) (ft)

10445 10445 0.0018 Hagedorn FlowlineBrown Pressure

(psia)100

( Pflp )

( 1 ) Evaluate the results of the 3-1/2" tubing well completion only (no flow line connected). Discuss.

( 2 ) Connect a 1000 ft flowline of 2-7/8" O.D. and assume it is on level ground. What is the new well flow rate at Pffl = 100 psia and the Beggs & Brill flowline correlation ?

( 3 ) How much rate loss has occurred due to the back pressure of the flowline connection?

( 4 ) If the Pffl is increased to 225 psia from 100 psia, and the flowline lengthened to 1450 ft to reach facilities located farther away, what will be the new flow rate through the pipeline? Discuss.






5-6

Exercise: PO2 - 04 & 04 A & 04 BFlowing Tubing Pressure And 4" Flowline Connected

- Well data is identical to Prob # 03.- A development well was drilled to 10445 ft and plugged back to 10150 ft. The reservoir mid point is at 10000 ft.- A single well test of the reservoir at 10000 ft was obtained: flowing 1410 STBFD at 2440 psia Pwf.- Production engineering has begun evaluation of the mechanical completion.- A Vogel IPR has been chosen for the design analysis.



oil 38 0.65 650 10 1.02 120 147 198 4660 0.466



10000 10000 3-1/2" 9.3 No Yes 1000 No No4" Sch 80 No Elev

ChangeDrilled Drilled Wellbore FlowlineDepth Depth Pipe Hydraulics Temp


(ft) (ft)


(psia)150

( Pflp )

( 1 ) Problem # 03 evaluated the results of the 3-1/2" tubing well completion only (with no flow line connected).

( 2 ) Connect a 1000 ft flowline of 4" O.D. and assume it is on level ground. What is the new well flow rate at Pffl = 150 psia and the Beggs & Brill flowline correlation ?

( 3 ) How much rate loss has occurred due to the back pressure of the flowline connection?

( 4 ) If the Pffl is increased to 325 psia from 150 psia, and the flowline lengthened to 2550 ft to reach facilities located farther away, what will be the new flow rate through the pipeline? Discuss.






5-7

Exercise: PO2 - 05High Water Cut Well - Add Gas Lift Artificial Lift

- A development well was drilled to 10179 ft and plugged back to 10150 ft. The reservoir mid point is at 10000 ft.- A single well test of the reservoir at 10000 ft was obtained: flowing 1250 STBFD at 2859 psia Pwf and w.c. of 42%.- Production engineering has begun evaluation of the mechanical completion.- A Vogel IPR has been chosen for the design analysis.



oil 38 0.65 400 42 1.02 120 140 190 4550 0.455( Pftp )



10000 10000 3-1/2" 9.3 No No No No



( 1 ) Evaluate the results of the proposed 3-1/2" tubing completion. Discuss.

( 2 ) How will the well perform and what will be the intersection of the IPR and IPC curves at that time? Explain what is happening.

( 3 ) If 700 scf/stb of 0.65 specific gravity gas is employed for a gas lift system with the operating valve at 6550', what will be the new performance of the well?






5-8

Exercise: PO2 - 06 & 06API IPR Inflow Performance And Completion Selection

- An exploration well was drilled to 7955 ft and plugged back to 7650 ft.- The reservoir at 7500 ft is estimated to have a PI = 1.887 B/D/psi.- Production engineering has begun evaluation of the mechanical completion.



oil 34 0.65 650 0 1.02 133 155 182 3338 0.445( Pftp )



7500 7500 2-3/8" 4.7 No No No No



( 1 ) Evaluate the proposal of installing 2-3/8" as the initial tubing completion choice for Pftp = 155 psia.

( 2 ) Construct a wide range of Pftp operating pressures and comment upon the results of this study.

( 3 ) Construct a tubing liquid rate vs. Pthp plot for item (2) using the graph utility of SNAP.

( 4 ) Evaluate tubing sizes of 2-7/8", 3-1/2", and 4" to determine flow rates at 155 psia, 200 psia, and 250 psia Pftp.






5-9

Exercise: PO2 - 07

Darcy Equation IPR Inflow Performance And Completion Selection

- A infill development well was drilled to 7855 ft and plugged back to 7680 ft.- The reservoir at 7500 ft and the following data is available to describe the producing interval "AA" sand.

k (md) = 65 Drain Radius (ft) = 1500 skin = 0h (ft) = 30 Well Radius (ft) = 0.401

- Production engineering has begun evaluation of the mechanical completion.



oil 31 0.65 525 38 1.02 143 188 179 3338 0.445( Pftp )



7500 7500 see (1) see (1) No No No No



( 1 ) Using the Darcy IPR equation to represent the reservoir, evaluate F-25 grade with sizes 2-3/8", 2-7/8", 3-1/2", & 4" at the Pthp = 188 psia.

( 2 ) Determine the expected net oil rates for each tubing size. Why might not the maximum rate choice size tubing be run in the initial completion, noting that the water cut is currently 38% for this infill development well.






5-10

Exercise: PO2 - 08Darcy Equation IPR Inflow Performance With Perf Model

- This well perforation model problem uses the same well as in example problem PO2 - 07.- A infill development well was drilled to 7855 ft and plugged back to 7680 ft.- The reservoir at 7500 ft and the following data is available to describe the producing interval "AA" sand.


- Prod engineering has included the design below for the perforated interval in the evaluation of the mechanical completion. perm zone = 20% thickness = 0.5 in perf intvl = 32 ftcompacted of k res compact zone

perf = 8.00 in shots per = 4 perf diameter = 0.5 inpenetration foot

perf = 0.85efficiency ( constant )



oil 31 0.65 525 38 1.02 143 188 179 3338 0.445( Pftp )



7500 7500 see (1) see (1) No No No No



( 1 ) Again as in problem 07, and using the Darcy IPR equation to represent the reservoir, evaluate 2-3/8", 2-7/8", 3-1/2", & 4" at the Pthp = 188 psia and also including the perforated interval description above.

( 2 ) Determine the new net oil rates for each tubing size. Why again might not the maximum rate choice size tubing be run in the initial completion, noting that the water cut is currently 38% for this infill development well.

( 3 ) What is the loss of rate through the pressure drop at the perforations?

( 4 ) Run the problem again using 65% larger charges sizes with the following characteristics on perf test.

perm zone = 20% thickness = 0.35 in perf intvl = 32 ftcompacted of k res compact zone

perf = 12 in shots per = 4 perf diameter = 0.825penetration foot

( 5 ) What are the new results using the larger charges?

( 6 ) What are the new results using the larger charges at an increased shot density of 8 SPF & 12 SPF (shots per foot)?






5-11

Exercise: PO2 - 09Flowing Tubing Pressure And 2-1/2" Flowline Connected And Choke Installed

- Well data is identical to Prob # 03.- A development well was drilled to 10445 ft and plugged back to 10150 ft. The reservoir mid point is at 10000 ft.- A single well test of the reservoir at 10000 ft was obtained: flowing 1410 STBFD at 2440 psia Pwf.- Production engineering has begun evaluation of the mechanical completion.- A Vogel IPR has been chosen for the design analysis.



oil 38 0.65 650 10 1.02 120 147 198 4660 0.466



10000 10000 3-1/2" 9.3 No Yes 2550 No No2-1/2" No ElevSch 80 Change

Drilled Drilled Wellbore FlowlineDepth Depth Pipe Hydraulics Temp


(ft) (ft)


(psia)325

( Pflp )

( 1 ) With the Pffl increased to 325 psia from 150 psia, and the flowline lengthened to 2550 ft to reach facilities located farther away, what will be the new flow rate through the pipeline at three different choke settings of: 32/64ths (1/2 inch), 48/64ths (3/4 inch), and 64/64ths (1 inch) ?

( 2 ) Lengthen the flowline to 5500 ft due the need to route production to another separator plant. Re-run Problem in #1 above and compare with the results of Problem #1.






5-12

Exercise: PO2 - 10SCSSSV Malfunction Downhole

- An offshore operator completed a well that had been drilled to 10355 ft MD and plugged back to 10200 ft. The reservoir at 10000 ft was initially tested per expectations by the completions department at 5600 BOPD before turning the well over to Production following the drilling and completions exercise. Within several days, production unexpectedly fell back to about 1395 BFPD dry oil. The well's primary cement job was excellent per CBL run and no water (or unexpected gas) was flowing with the diminished rate. Inspection of the emergency shut down well control system led to the discovery that the SCSSSV had failed and that it had possibly been damaged while running in the hole. - Use the Vogel IPR with Vogel data being: Pres = 4552 psia, Test Rate of 3522 BFPD, and Pwf = 2998 psia.



oil 36 0.65 625 0 1.02 118 158 195 4552 0.455( Pftp )



10000 10000 5" 13 Yes No No No4.494" I.D.



( 1 ) Evaluate the flow performance of the well completion with the SCSSSV fully operating.

( 2 ) Evaluate the flow performance of the well completion with the SCSSSV partially failed (mechanical reasons). Use the Ros choke correlation and a tubing obstruction of 0.35" at 660 ft deep in the tubing as the location of the failed SCSSSV.

( 3 ) Remove the obstruction and review the well's performance operating at the Pftp of 125 psia.






5-13

Exercise: PO2 - 11Downhole Tubing Buckled

- An operator completed a well that had been drilled to 10644 ft MD and plugged back to 10285 ft. The reservoir at 10000 ft was tested by the completions department at 2130 BFPD at 10% water cut. - Six months after completion, the rate suddenly dropped off and possible hole mechanical problems were suspected.- A wireline unit was called out and it was determined that the tubing string completion had an obstruction. Subsequent wireline runs with impression block and swedge tools determined that the tubing was buckled at approximatgely 8000 ft.- Use the Vogel IPR with Vogel data being: Pres = 4545 psia, Test Rate of 2498 BFPD, and Pwf = 2888 psia.



oil 33 0.65 600 10 1.02 120 128 197 4545 0.454( Pftp )



10000 10000 4-1//2" 12.75 No No No No3.958" I.D.



( 1 ) Evaluate the flow performance of the well completion with the tubing condition intact and without problems.

( 2 ) Evaluate the flow performance of the well completion with the tubing in buckled condition downhole. Use the Gilbert choke corrrelation and a tubing obstruction of 0.25" at 8000 ft deep in the tubing as the location of the buckled tubing.

( 2 ) Assume that the well is worked over to pull & re-run tubing and review the well's performance operating with repaired tubing at the Pftp of 160 psia.






5-14

Exercise: PO2 - 12Vogel Equation IPR For Layered Reservoir

- A infill development well was drilled to 10565 ft and plugged back to 10200 ft.- The reservoir datum is at 10000 ft is layered per the following data describing the producing intervals "AA", "BB", and "CC".

"AA" k (md) = 10 Drain Radius (ft) = 1500 skin = 0h (ft) = 20 Well Radius (ft) = 0.401 BS&W = 10%

"BB" k (md) = 50 Drain Radius (ft) = 1500 skin = 0h (ft) = 5 Well Radius (ft) = 0.401 BS&W = 0%

"CC" k (md) = 50 Drain Radius (ft) = 1500 skin = 0h (ft) = 10 Well Radius (ft) = 0.401 BS&W = 20%



oil 38 0.65 750 (see above) 1.02 120 140 188 4550 0.455( Pftp ) (initially)

"AA","BB","CC"



10000 10000 3-1/2" 9.3 No No No No



( 1 ) Using the Darcy IPR equation to represent the reservoir, evaluate 3-1/2" tubing at the Pthp = 140 psia.

( 2 ) Evaluate the adjacent well with similar properties plus the added 3 logged sands per below:

"AA" k (md) = 10 Drain Radius (ft) = 1500 skin = 0h (ft) = 20 Well Radius (ft) = 0.401 BS&W = 10%Pres = 4550

"BB" k (md) = 50 Drain Radius (ft) = 1500 skin = 0h (ft) = 5 Well Radius (ft) = 0.401 BS&W = 0%Pres = 4550

"CC" k (md) = 50 Drain Radius (ft) = 1500 skin = 0h (ft) = 10 Well Radius (ft) = 0.401 BS&W = 20%Pres = 4550

"DD" k (md) = 10 Drain Radius (ft) = 1500 skin = 0h (ft) = 10 Well Radius (ft) = 0.401 BS&W = 10%Pres = 4400

"EE" k (md) = 50 Drain Radius (ft) = 1500 skin = 0h (ft) = 25 Well Radius (ft) = 0.401 BS&W = 0%Pres = 4560

"FF" k (md) = 10 Drain Radius (ft) = 1500 skin = 0h (ft) = 15 Well Radius (ft) = 0.401 BS&W = 10%Pres = 4550






5-15

Exercise: PO2 - 13Horizontal Well IPR Babu & Odeh Equation

- A horizontal infill development well was drilled to 11930 ft MD 7855 ft and plugged back with a 2000 ft extended reach.- The well TVD reservoir depth is 8000 ft and the Babu & Odeh model chosen to evaluate the horizontal well completion.

perm k = 50 md drainage area for comp. vertical well: = 275 Acres"x" direction Dist. to drainage end from well heel: y1 = 1000 ft

Horizontal section length: y2 = 2000 ftperm k = 50 md Drainage length along well path: y = 4000 ft

"y" direction Dist. to well axis from closest side : x0 = 1500 ft

Drainage width across well path: x = 3000 ftperm k = 10 md Dist. to well axis from the formation top : z0 = 25 ft

"z" direction formation thickness : h = 50 ftclassic mechanical skin factor : s = 0

wellbore radius = 0.401 ft



oil 27 0.7 600 0 1.02 135 400 214 3200 0.445( Pftp )



7855 7855 5 11.5 No No No No No4.56


8000 11930 0.0018 Ansari

( 1 ) Using the Babu & Odeh IPR model what is the expected production rate from the well assuming a 400 psia Pftp?

( 2 ) What is the expected production rate from the well , if the well is placed 1 foot from the top of the reservoir?

( 3 ) After resetting to base case, what is the expected production rate from the well , if the well heel is placed 1 foot from the edge of drainage?

( 4 ) After resetting to base case, what is the expected production rate from the well , the vertical permeability is reduced to 1 md?

( 5 ) After resetting to base case, what is the expected production rate from the well , if thickness is increased by a factor of 2? Plase well half the distance from the top of the reservoir.






5-16




Problems / Handouts

Problems:

2) Gas Completion Problems

Section: P02

5-17

Exercise: PO2 - Gas Completion Problems



oil




( 1 )

( 2 )

( 3 )






Gas Completion Problem Set

5-18

Exercise: PO2 - 51Gas Well Inflow Performance And Completion Selection

- A gas development well was drilled to 8075 ft and plugged back to 7780 ft.- A four point flow after flow test of the reservoir at 7500 ft was obtained: C and n were calculated at 0.0026 and 0.91.- Production engineering has begun evaluation of the mechanical completion.



gas 55 0.65 0 1.02 152 190 180 3405 0.454wet gas - 10 Bbl / mmscf ( Pftp )



7500 7500 2-7/8" 6.5 No No No No2.441" I.D.


8075 8075 0.0018 Ansari

( 1 ) Evaluate the proposal of installing 2-7/8' completion tubing in the well to operate at a Pftp of 190 psia.

( 2 ) Discuss the shapes of the IPR and IPC curves and the meaning of the curve shapes.

( 3 ) Discuss the meaning of the curves intersection point.






liquid yield

5-19

Exercise: PO2 - 52Gas Well Inflow Performance And Completion Selection, Coefficient "n" Variation Effects

- This problem uses the well data from problem # 51.- A gas development well was drilled to 8075 ft and plugged back to 7780 ft.- A four point flow after flow test of the reservoir at 7500 ft was obtained: C and n were calculated at 0.0026 and 0.91 originally but the data from the field indicated an "n" value range going from 0.76 to 0.96. - Production engineering has begun evaluation of the mechanical completion.



gas 55 0.65 0 1.02 152 190 180 3405 0.454( Pftp )



7500 7500 2-7/8" 6.5 No No No No


8075 8075 0.0018 Ansari

( 1 ) Investigate the effects of "n" ranging as above in the field data.

( 2 ) Discuss the shapes of each IPR curve as "n" varies, the IPC curve intersection, and the meaning of the curve shapes.

( 3 ) What can be done to attempt a quick remedy at "fixing" well performance with low "n" value?






liquid yielddry gas - 10 Bbl / mmscf

5-20

Exercise: PO2 - 53Gas Well Quadratic Equation Inflow Performance

- A gas development well was drilled to 8071 ft and plugged back to 8060 ft.- With available data below, the quadratic IPR model was chosen for completion design purposes.




gas 55 0.65 0 1.02 152 190 194 3584 0.448( Pftp )



8000 8000 3-1/2" 9.3 No No No No2.992" I.D.


8071 8071 0.0018 Ansari

( 1 ) Evaluate the completion by looking at a range of Pthp for 3-1/2" completion tubing. Discuss.

( 2 ) A commercial opportunity has arisen to sell high pressure gas at large volumes. Evaluate 5-1/2" tubing (4.892" I.D.) delivered at 325 psia. Discuss.






dry gas - 10 Bbl / mmscfliquid yield

5-21

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