5. Gas Ligt - Diseño y Analisis

7/28/2019 5. Gas Ligt - Diseo y Analisis

1/39

EX 5 1

Example 5

FloSystem User Course

Gaslift Design and Analysis


2/39

EX 5 2

Gaslift Design

Overview

A Gaslift design for a well that does not flow naturally

Select Data Preparation and check : Reservoir data

Fluid data

Deviation data - Well data

Equipment Data - Well Data


3/39

EX 5 3

Reservoir DataEnter Reservoir Data

Fluid Type is Black Oi l

Entry Model is Manual

PI = 1.3 STB/day/psia

IPR model = Vogel

Reservoir Pressure = 5100 psia

Reservoir Temperature = 230 F

Fluid Parameters for Black Oil

API = 27.5 GOR = 320

Water cut = 20 %

Gas specific gravity = 0.74

Water salinity = 200 kppm


4/39

EX 5 4

Deviation Data


5/39

EX 5 5

Equipment Data


6/39

EX 5 6

Analysis :Operating Point


7/39

EX 5 7

No operating point:Natural flow


8/39

EX 5 8

Gaslift Data

Select Data Preparation - Gaslift Data

Use the following design parameters :

Casing Injection Pressure = 1200 psia

Gas Specific Gravity = 0.65

Differential pressure across the Valve = 100 psia

Lift gas injection rate 1.5 MMscf/day

Deepest point of injection = 40 ft above tubing shoe

These are the minimum data to calculate the

Operat ing Poin tfor the

Deepest Point of Injection


9/39

EX 5 9

Gaslift Design :Deepest Injection Point


10/39

EX 5 10

Gaslift Design Rate2513 STB/day


11/39

EX 5 11

Pressure vs DepthInjection Depth: 8120 ft TVD


12/39

EX 5 12

Gaslift Design

The design parameters used gives : Liquid rate = 2513 STB/day

Oil rate = 2010 STB/day

Water rate = 503 STB/day

Gaslift Valve Depth at 8121 ft. for given Qgi, CHP.

Sensitivity studies can now be made

gaslift injection rate 1.5, 2, 2.5 MMscf/day etc.

water cut increasing to 20, 30, 50, 70 % etc.

At this stage the design parameterscould also be revised (e.g. Casing injectionpressure, wellhead pressure)


13/39

EX 5 13

Sensitivity of lift gasinjection rate

Note PaybackRatio


14/39

EX 5 14

Sensitivity of anincreasing water cut


15/39

EX 5 15

Gaslift Design :Final Parameters

The final parameters for the optimum design willdepend of the actual operating restrictions.

The initial lift gas injection rate, casing injection

pressure and valve differential pressure will be usedfor the Gasl i f t Design

Select Analys is - Gasl i f t Design....

Revise the parameters again and set the top node orChristmas tree pressure and the specific gravity ofthe fluid in the annulus


16/39

EX 5 16

Gasl ift Des ign ....

Design Margins...

Design

Sizing...


17/39

EX 5 17

Gaslift Design....

When click the Designbutton

First:

The temperature profile is calculated using the

model selected

Object ive tubing f lowing gradientis computedtop down

The gas is forced at the specified MD of

injection (Data Preparation -Gasli ft data...)Second:

Space unloading valves and define operatingvalves. Below operating valve space dummy

valves according to minimum spacing


18/39

EX 5 18

Des ign Marg ins ....Casing Controlled Valves + Valve

Number

Casing Controlled Valves and Valve Number

Additionally

The fluid in the annulus is brine of 0.45 psi/ft

Minimum valve spacing below the operating valve =

450 ft. (100 psi)


19/39

EX 519

Gasli f t Design ...Design Marg ins...

Kickoff Pressure

Casing closing

pressure margin

Margin at valve 1

Increment per valve


20/39

EX 520

Gasli f t Des ign ...Gaslift Valves Spacing


21/39

EX 521

Gasli f t Design ...Gaslift Valves Spacing

Operating Valve with all

design margins

Design Operating valve

Minimum valve spacing


22/39

EX 522

Gasli f t Des ign ...Spacing ofDesign Operat ingValve

The position of the Design Operat ing valvedepends ifthe spacing finds the following constraints:

1. Next position less than minimum valve spacing

Last valve is marked as Operating valve and valvespacing below equal to minimum spacing.

The Design Operat ing valveis marked at depth with

enough differential pressure (relative to uncorrectedtubing pressure)


23/39

EX 523

Gasli f t Des ign ...Spacing ofDesign Operat ingValve

2. Pcasing- Ptubing< differential pressure

Move up until it reaches a depth where the

differential pressure is met The new position is the Design operat ingvalveif spacing greater than minimum valvespacing

If the new position is less than minimumvalve spacing the Design Operating valve ismarked at the valve above


24/39

EX 524

Gasli f t Design ...Spacing ofDesign Operat ingValve

3. Next position is below Max MD of in ject io n

The Design Operat ing valvewill be positioned at MaxMdprovided Pcasing-Ptubing> valve differentialpressure

If Pcasing-Ptubing


25/39

EX 525

Gaslift Design Results

Active valves 6 and dummy valves 12

5 unloading valves

1 operating valve : Valve Depth = 7621 ft TVD (8068 ft MD)

Casing Pressure = 1300 psia

Tubing Pressure = 1195 psia

Temperature = 212.4 oF

12 Dummy valves below the operating valve spacedat 450 ft (TVD)


26/39

EX 526

Gaslift Design Results

A new casing injection operating pressure of1131 psia can be selected

However this new injection pressure will give a

liquid rate = 2434 STB/day because If the casing injection pressure is kept at 1200

psi, then the liquid rate = 2491 STB/day(compared with design value of 2513 STB/day)


27/39

EX 527

Sizing.... Facility

1. Port Size calculation using the Thornhill Craverequation.

2. Opening and Closing pressures computation for

each valve3. Dome and Test Rack Opening pressures

computation for each valve

4. Valve type selection :

Gas Charged Spring

Orifice


28/39

EX 528

Sizing....Facility

Gasli f t Design ... results transferred to Sizing...:

Column name

Gaslift rate Qgi Valve depths MD and TVD

Wellbore temperature Temp

Tubing transfer pressure Pt P tubing

Casing pressure Pvo P open valve


29/39

EX 529

Sizing.... Facility

1. Port Size

Valve type and Port Size

Critical Flow Flag

Pt

Pvo

F ilit


30/39

EX 530

Sizing.... Facility

1. Port Size

Thornhill-Craver is solved with:

Pt (downstream pressure)

Pvo (upstream pressure)

Temp

Qgi

Discharge coefficient (Disch Coeffcolumn) default

value is 0.865All these values can be edited independent of the

previous gaslift design results

The column Critshows whether the valve is oncritical flow


31/39

EX 531

Sizing.... Casing controlled

2. Opening and Closingpressures

Two methods to determine Opening and Closingpressures:

A. Use Pvo (from Gaslift Design)

B. Specify a surface closing pressure Psc

(P close sur f, column)

Update ratio R = tubing port area /bellows area

R in the order of 0.1 i.e. most of the bellows feel thecasing pressure


32/39

EX 532



A. Use Pvo by setting NOin Calc by P closespreadsheet column

B. Use P close surf by sett ing YESin Calc by P close

spreadsheet column

Select calculation method


33/39

EX 533



A. Use Pvo:

The Dome pressure is calculated from:

Pd = Pvo(1- R)+Pt(R)

The Valve Closing pressure Pvc is equal to Pd.

Pd & Pc valvecolumn in spreadsheet

The surface Closing pressure Psc follows bycorrecting Pvc for the gas gradient

P close sur fcolumn in spreadsheet

The surface Opening pressure Pso follows bycorrecting Pvo for the gas gradient


34/39

EX 534

PvcPsc



Pt

R

Pvo Pso


35/39

EX 535



B. Use P close surf(Psc)

Enter the Psc in the spreadsheet (e.g. 1300 for thefirst valve)

The Pvc is computed by using the gas gradientand Psc. By definition this is the in-situ domepressure Pd

Pd & Pc valvecolumn in spreadsheet

The valve Opening pressure Pvo is calculated fromPd, R and Pt:

Pvo= (Pd-Pt*R) /(1-R)

P open valvecolumn

P open sur f(Pso) follows by correcting Pvo for the gas

gradient


36/39

EX 536

B. Use P close surf (Psc)



YesPsc


37/39

EX 537


3. Pd and TRO openingpressures

The in-situ (Pvo, Pvc) and surface (Psc, Pso) and thedome pressure (Pd) have been calculated at the valvetemperature

Pd is converted to its value at 60 oF

P dom e at 60oFcolumn

The Test Rack Opening TRO is derived from:

TRO= (Pdome at 60oF- 14.65*R) /(1-R)


38/39

EX 538


3. Pd and TRO

opening pressureP dome at 60F

Pd at valve Temp

TRO


39/39

EX 539

Gaslift DesignSummary

Example of Gaslift design for a well that does notflow naturally

Design Margins

Casing-controlled valves

Fluid-controlled valves

Sizing Facility

Port size

Opening and closing pressures Dome and Test Rack Opening pressure

Valve type selection

5. Gas Ligt - Diseño y Analisis

Documents

Transcript of 5. Gas Ligt - Diseño y Analisis