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DOElET/27141-4

(DE82009120)

Distribution

Category UC66c

GEOTHERMAL

WELL

DESIGN HANDBOOK

February ,

1982

P re pa red f o r

Department o f Energy

D i v i s i o n of Geothermal Energy

Contract DE-AC03-78ET27141

Prepared by

L a b o r a to r i e s f o r A p p l i e d M e c h a n i c s

De n v e r Re s e a r c h I n s t i t u t e

Denver, Colorado

and

Coury and Ass oc i a tes , In c .

Denver , Co lorado

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..

I I

C h a p t e r 1 .

C h a p t e r

1 1

.

C h a p t e r 1 1 1 .

C h a p t e r 1 V .

T A B L E OF C O N T E N T S

Page

1 N T R O D U C T l O N . . . . . . . . . . . . . .

1

D I S C U S S I O N O F H A N DB O OK P R OC E SS . . . . . 3

S A M P L E C A L C U L A T I O N S . . . . . . . . . .

3

P H Y S I C A L P R O P E R T I E S G R A P H S A N D T W O - P H A S E

F L O W W E L L H E A D P R E S S U R E G R A P H S

. . . . .

9

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I I NTRODUCT ON

This handbook provides

a

simplified process for the user, at

a

desk

and using

a handheld calculator, to estimate the performance of geothermal

wells which are produced by natural,

flashing

flows.

the user

must

indicate the well diameter

and

depth,

and

the reservoir con-

ditions. The process presented here then enables the user to determine

To accomplish this,

the total pressure drop

in

a flowing well, and therefore to find the

fluid

pressure, temperature and steam

quality

at the wellhead.

ing the handbook process to several input data sets,the user can compile

By apply-

sufficient information to determine the interdependence of input and out-

put parameters. For example, a g r a p h of flowrate a s a function of well-

/

head pressure

may

be constructed, or the effect of diameter changes on

pressure at the wellhead

m i g h t

be examined.

To make the process of the handbook possible, several

s i m p l i f y i n g

assumptions were made:

0 adiabatic wellbore flow (no heat transfer through the

we1 casing)

0

no dissolved solids

in

the geothermal fluid

0

no dissolved gases

in

the geothermal

fluid

0 single phase flow in the wellbore at producing zone.

These assumptions allow the elimination of several additional variables

from the problem formulation. This simplified formulation lends itself

well to the treatment given in the handbook.

There are 5 (five) input parameters to be specified

by

the user:

0

We1 bore

d

iemeter

Depth of well to the top of the producing zone

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3

I I .

DISCUSSION

OF

THE HANDBOOK

PROCESS

The process used in this handbook to find the pressure drop in a