INTERFERENCE TEST OF SIBAYAK GEOTHERMAL FIELDNORTH SUMATRA - INDONESIA

摘要

Interference test has been recognized as avaluable technique for evaluating reservoir propertiessuch as permeability thickness and storativity over anarea where active and observation wells are located.Interference test can also provide qualitativeindications of reservoir heterogenities andcommunication between two or more wells. Theavailability of sophisticated pressure recordersencourages providing reliable data and improvedaccuracy. Interference test of Sibayakgeothermal field that has been carried out inDecember 1998 to September 1999 is examined toprove two major fault which are predicted supportingpermeability of this area. The presence of linearboundary can be determined by using a new semi-logtype curve matching (Sageev et al, 1985). Log-logtype curve (Theis Curve) can also be employed todetermine the interwell properties I.e. transmisivityand storativity.The first test that conducted by measuringSBY-8 response to SBY-5 discharge, does not reflectpresenting of either fault F4 or F1. The second test ofwell SBY-7 response to SBY-5 discharge, indicatesshifting of the pressure response to the constantpressure linear boundary curve. It is shown in a loglogplot matching (Theis curve) and more clearly innew semi-log. For Sibayak geothermal field the areabetween SBY-8 and SBY-5, permeability thickness is40.3× 10-12 m3 and storativity is 2.64× 10-8 m/Pa.The area between SBY-7 and SBY-5, permeabilitythickness is 48.3× 10-12 m3 and storativity is 1.63×10-8 m/Pa.