Pipesim 2006.1 Fundamentals Gaslift

Artificial Lift Design Schlumberger

Gas Lift Design – New Mandrel Spacing

Learning Objectives

This case study will demonstrate the following workflow:

! Perform Well Model / Nodal Analysis to analyze a well’s requirement for artificial lift

! Evaluate the Gas Lift Response

! Perform a Gas Lift Design (using the “IPO Surface Close” method)

PIPESIM 2006.1 Fundamentals 91


Exercise 1 – Well Model / Nodal Analysis

following basic data, Given the construct a well model and perform a Nodal Analysis at bottomhole. Assume no gas lift valves in the well at this stage.

Confirm that the well will not flow naturally assuming a wellhead pressure of 110 psig.

lack Oil PVT Data

Water Cut 55 %

B

GOR 300 scf/stb

Oil Gravity 32 oAPI

Gas Gravity 0.64

Water SG 1.05

Flow Correlation

Select the Hagedorn and Brown vertical flow correlation.

Wellbore Data

MD (ft) TVD (ft)

0 0

7550 7550

mid-perf depth = 7550 ft


Artificial Lift Design SchlumbergerGeothermal Survey

MD (ft) Ambient Temp (F) U Value (Btu/hr/ft2/F)

0 50 2

7550 175 2

Tubing/Casing Dimensions

2 7/8 “ (2.441” ID) tubing from surface to 7500 ft

7 “ (6.184” ID) casing from 7500 ft to 7550ft

Reservoir and Inflow Data

Reservoir Pressure 2800 psig

Reservoir Temperature 175 oF

Productivity Index 2.5 stb/d/psi

Use Vogel below the bubblepoint.

Steps:

1. Construct a Well Model and enter the above data. Place the Nodal Analysis icon at bottomhole.

2. Run Operations > Nodal Analysis.

a. Enter the Given Outlet Pressure (110 psig).

b. Leave “Max Rate” empty (PIPESIM will calculate rates up to the AOFP).

c. Leave “Inflow Sensitivity” and “Outflow Sensitivity” empty.

3. Inspect the plot.



Exercise 2 – Evaluate the Lift Gas Response

e

Steps:

1. Select the Lift Gas Response operation from the Artificial lift > Gas Lift submenu.

2. Enter gas lift rate sensitivity values of 0 to 5 mmscf/d in increments of:

a. 0.1 mmscf/d up to 1.0 mmscf/d

b. 0.5 mmscf/d up to 5.0 mmscf/d

3. Enter sensitivity values of 150 and 250 psi for the Minimum injection gas "P.

4. Use an injection gas surface pressure of 1000 psig and assume an injection gas surface temperature of 80 ºF.

5. Ensure that the gas injection depth is set as Optimum Depth of Injection.

Using the Lift Gas Response operation, determine the gas lift rate that will be used for thdesign.

Note th point at the optimum rate is about 4840 ft. This will be iscusse

at the deepest injection d in a later exercise. d



Exercise 3 – Perform Gas Lift Design (using the “IPO Surface Close” metho

Given the design conditions below, d he following:

. Determine the required Mandrel spacing to unload the well.

2. The test rack pressure of each o

Design

d)

etermine t

1

f the unloading valves.

Conditions

Design Control Parameters

Design Spacing: New Spacing

Design Method: IPO-Surface Close

Top Valve Location: Assume Liquid to Surface

Manufacturer: SLB (Camco)

Type: IPO

Size: 1’’ (Tubing size 2 7/8 < 3 ½)

Series: BK-1

Min Port Diameter: None

Unloading Temperature: Default (Unloading)

Production Pressure Curve: Production Pressure Model

Design Parameters

Kickoff Pressure: 1000 psig

Operating Injection Pressure: 1000 psig

Unloading P rod. Pressure: 110 psig

Operating Prod. Pressure 110 psig

Target Injection Gas Flow rate: 1.25 mmscf/d

Injection gas Surface Temp: 80 °F

Inj Gas Specific Gravity: 0.64

Unloading Gradient: 0.465 psi/ft

Minimum Valve Spacing: Calculated

Minimum Valve Inj DP: 150 psi

Bracketing Options: Not selected

Safety Factors

Surface Close Pressure Drop Between Valves: 15 psi

Locating DP at Valve Location: 50 psi

Transfer Factor: 0

Place Orifice at operating valve location: Yes

Discharge Coefficient for Orifice: 0.865


Artificial Lift Design SchlumbergerSteps:

on Perform Design.

1. Go to Artificial Lift > Gas Lift > Gas Lift Design in the top menu.

2. Enter the Gas Lift Design Data given above.

3. Click

4. Select Graph to plot the gas lift design response.


Artificial Lift Design SchlumbergerGas Lift Design – Current Mandrel Spacing

Learning Objectives

In this case study you will learn how to design a gas lift system with a current

alve system in the tubing

! Perform a ration to find the maximum depth that could be ach j = 1000 psig and Lift gas mscf/d)

! Per esponse operation to prod ate vs. lift gas rate

! Design using the current mandr

mandrel spacing using the following workflow:

! Install a Gas Lift V

Deepest Injection Point opeieved. (Using Pin rate = 1.25 m

form a Gas Lift r uce a graph of oil r

the gas lift system el spacing



Exercise 1 – Install a Gas Lift Valve System, Deepest

study, insert the following Gas lift valve

Injection Point Operation

Using the model created during the previous casesystem into the tubing:

Equipment MD Properties Label

Gas Lift Valve 1500 IPO-1/8 BK-1






Steps:

1. In the Downhole Equipment tab (located in the detailed tubing dialog), select the G/LValve System button and check the “Edit Valve Details” (only used for Gas Lift Diagnostics) box. Specify the spacing shown above in the tubing user form.

2. Select the first row in the user form, click on the Add…[Valve Lookup] button. The Gas Lift Valve Selection user form displays.

3. Select SLB (Camco) as the manufacturer, IPO as the type, 1” as the size and BK-1 as the series. Select Refresh.

4. Click on Add valve to add the required valve.

5. Add the depth of the first valve in the gas lift valve system user form.

6. Repeat the above steps for all the valves.

7. From the Artificial Lift > Gas Lift menu, perform a Deepest Injection Pointoperation as shown below. Use a lift gas rate of 1.25 mmscf/d and an injection pressure or 1000psig. Then click on the Calculate button.




The maximum depth of injection is 4770 ft; therefore, you should be able to inject at the mandrel located at 4700 ft. The corresponding oil rate should be 1882 STBD.

This shows that a gas lift valve cannot be set below the DIP.


Exercise 2 – Generate the Gas Lift Response Curves

Gas Lift Response operation to prPerform a oduce a graph of oil rate vs. lift gas rate

only option is selected and run the operation.

(Use Minimum gas injection Delta P of 150 psi and 250 psi as the sensitivity and lift gas rates ranging from 0 to 5 mmscf/d in increments of 0.5 mmscf/d. Ensure that the Injection at valve depth



Exercise 3 – Design the Gas Lift Valve System using the Current Mandrel Spacing

Given the design conditions (Identical to the previous case study) and the current mandrel spacing, perform the gas lift design. Select current spacing in the design control tab prior to performing the design. Use 1.25 mmscf/d as the lift gas rate.



It is important to note that we are not injecting at the mandrel located at 4700 ft, but at the mandrel located at 4200 ft. The rate is not 1871 stb/d, but 1708 stb/d. This is due to the fact that the Deepest Injection Point operation does not take into account the 15-psi pressure drop in casing pressure for each unloading valve.

It is also important to notice that when designing for a current mandrel spacing, the depth between valves is fixed. It is the transfer pressure that is calculated at each valve. When the transfer pressures lie to the left of the production pressure curve or the equilibrium curve, it may not be possible to transfer to the next valve.


Artificial Lift Design SchlumbergerExercise 4 – Gas Lift Diagnostics

that the system has been in operationAssuming for a while, and that the producing

1. Go to Artificial Lift > Gas Lift > Gas Lift Diagnosis.

2. Enter the current producing conditions and run the diagnostics.

3. Open the Data Sheet to determine which valves are open, closed or throttling, and the gas rates observed across each valve.

conditions have changed. The separator pressure is now 200 psia and the measured gas lift injection rate is 1.5 mmscf/d. Perform a gas lift diagnosis to ensure that the valves are operating under these conditions.

Steps:


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Pipesim 2006.1 Fundamentals Gaslift

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