Experiences on Geothermal Drilling in El Salvador Manuel Monterrosa - - PowerPoint PPT Presentation

Experiences on Geothermal Drilling in El Salvador

Manuel Monterrosa and Herbert Mayorga

Julio de 2007 ReykJavik, ENGINE WP 4

Contents

• History of geothermal drilling in El

Salvador

• Rigs available
• Well targeting
• Casing programme
• Problems during drilling operations
• Well testing

Short history of geothermal drilling

• The well AH-1 was the first well drilled in El Salvador by

Loffland Brothers during 1968

• The discharge test of well AH-1 was the kick off point for the

geothermal development in El Salvador. This well is still connected to the power plant.

• Since AH-1, over 100 wells have been drilled in El Salvador

contributing to the geothermal development Discharge Test AH-1

Rigs avalilable PSB owned

Rig Draw Work Horsepower Static Capacity Ton. Gross Capacity Ton. Structure Capacity Ton. Mass 6000 1200 250 350 300 Mass 4000 1100 250 340 328 Ideco H-525 650 160 250 300

Mass 6000, at Berlin Mass 4000, at Cuyanausul

Services companies available in El Salvador The services companies used in El Salvador are

• Cement services: BJ Services and Dowell

Schlumberger

• Directional Drilling:

Anadrill and Baker Int.

• Well Logging (cementing, MWD, and caliper):

Schlumberger

• Air services

Weatherford

Well targeting

San José

475.26 m

AH33C

000 41300 412500

Falla La Planta F a l l a B u e n a V i s t a Falla San Jose

Conventional Well casing programme

Well known areas, well casing programme

Problems during drilling operations

Loss circulations Loss circulation is happening when unexpected permeable zone is intersected, normally in shallows formations not the target area:

• Use of LCM materials, cement

and concrete plugs. In the medium or close to the reservoir (not in it).

• Cement plugs according to size
• f hole.
• Multiple plugs or changing

consistency and viscosity of it. Cementing casing

• A bad cementing job could cause

casing colapse when the pipe is heating up and the well is discharging, normally it is observed when shallow permeable zone was intersected and the cement did not work satisfactory.

• The cement casing job could

presents several problems, to prevent this, It is possible to use:

• Use of light weight cement.
• Use of tieback casing
• Cementing in loss circulation at the

bottom and cement from the upper part.

After cementing job CET/CBL must be necessary

Problems during drilling operations ..

• Change or large deviation to the target.
• Breaking of drilling pipe for over stress.
• Fishing job could be necessary to recover

the pipe. To prevent pipe stuck

• Improve the use directional drilling system

to prevent dog ledge conditions.

• Improve the mud flowrate and perhaps to

use air to improve the cuttings recovering

• Use additives to lubricate the fluid.
• More frecuently inspection test of the

drilling pipe. Stuck and fish The pipe stuck is happing when unstable formation is instersected and the mud is not working, in directional wells it is could happen if there are large severity or “dog ledge”. This condition, will cause: Blow out Control The blow out condition is happenig when steam are coming from the hole in unexpected way, in this case

• Use BOP is mandatory, BOP must

be in good condition (tested)

• Good emergency procedures and

personal trained for it.

• Survey equipment and drilling

crew alert to those conditions.

Well testing

• During drilling operation

the well testing are:

– Calipers, hole diameters – MWD (Measurement While Drilling) for directional data – CET/CBL cement bond logging – Water level and loss circulation data – Injectivity tests into the target zone – If available geophysical logging

20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 78 80 82 84 86

Bar 4 8 12 16 20 Caudal (Lts/s)

50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 Minutos 5 10 15 20 25

Caudal (lts/s)

45 50 55 60 65 70 75 80 85

Bar

45 50 55 60 65 70 75 80 85

Bar

Presiones 15 y 16 Marzo 07. Sondas,900 metros, Con linner

kpg 3896

KPG (2244) Con linner KPG ( 15 marzo 07) Caudal (15 marzo 07)

PRUEBAS EN POZO SV-2A, SAN VICENTE

i2= 0.87 lts/(bar s), 15 marzo 07, con Linner Orpower 7/ JRR/ 15 y 16Marzo 2007

Well completion

• When the drilling is finish

and the target have been reached, at least the next tests could be done:

– Final injectivity test – Warm up test including water level changes – Discharge test, when the thermodinamic condition indicate flowing conditions

Pressure 78 78.2 78.4 78.6 78.8 79 79.2 79.4 79.6 79.8 80 2000 4000 6000 8000 10000 12000 14000 16000 Pressure

CONGRATULATIONS, YOU HAVE A GOOD WELL