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
Draw Work Static Gross Structure Rigs avalilable Rig Horsepower Capacity Capacity Capacity Ton. Ton. Ton. Mass 6000 1200 250 350 300 PSB owned Mass 4000 1100 250 340 328 Ideco H-525 650 160 250 300 Mass 4000, at Cuyanausul Mass 6000, at Berlin
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 F AH33C a l l a 475.26 m B Falla San Jose u e n 0 a V i s t a Falla La Planta San José 0 000 412500 41300
Conventional Well casing programme
Well known areas, well casing programme
Problems during drilling operations Cementing casing Loss circulations • A bad cementing job could cause casing colapse when the pipe is Loss circulation is happening when heating up and the well is unexpected permeable zone is discharging, normally it is observed intersected, normally in shallows when shallow permeable zone was formations not the target area: intersected and the cement did not work satisfactory. • Use of LCM materials, cement • The cement casing job could and concrete plugs. presents several problems, to prevent this, It is possible to use: In the medium or close to the • Use of light weight cement. reservoir (not in it). • Use of tieback casing • Cementing in loss circulation at the • Cement plugs according to size bottom and cement from the upper of hole. part. • Multiple plugs or changing After cementing job CET/CBL must be necessary consistency and viscosity of it.
Problems during drilling operations .. Blow out Control Stuck and fish The blow out condition is The pipe stuck is happing when unstable happenig when steam are coming formation is instersected and the mud is from the hole in unexpected not working, in directional wells it is could way, in this case happen if there are large severity or “dog • Use BOP is mandatory, BOP must ledge”. This condition, will cause: be in good condition (tested) • Change or large deviation to the target. • Good emergency procedures and personal trained for it. • Breaking of drilling pipe for over stress. • Survey equipment and drilling • Fishing job could be necessary to recover crew alert to those conditions. 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.
PRUEBAS EN POZO SV-2A, SAN VICENTE Well testing 85 Presiones 15 y 16 Marzo 07. 80 Sondas,900 metros, Con linner kpg 3896 75 KPG (2244) 70 • During drilling operation Bar 65 60 the well testing are: 55 – Calipers, hole diameters 50 45 25 85 Con linner – MWD (Measurement While 80 20 KPG ( 15 marzo 07) 75 Caudal (15 marzo 07) Caudal (lts/s) Drilling) for directional data 15 70 Bar 65 – CET/CBL cement bond 10 60 55 5 logging 50 45 0 – Water level and loss 0 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 20 Minutos circulation data i2= 0.87 lts/(bar s), 15 marzo 07, con Linner 16 – Injectivity tests into the Caudal (Lts/s) 12 target zone 8 – If available geophysical 4 logging 0 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 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 Pressure – Warm up test including 80 79.8 water level changes 79.6 – Discharge test, when the 79.4 79.2 thermodinamic condition 79 indicate flowing conditions 78.8 78.6 78.4 78.2 78 0 2000 4000 6000 8000 10000 12000 14000 16000 Pressure
CONGRATULATIONS, YOU HAVE A GOOD WELL
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