Well Stimulation in Latera Field

Abstract

As part of a general program of geothermal well stimulation set up by ENEL (1), stimulation was performed on wells L1, L6 and L14 in the Latera geothermal field (northern Latium, Italy) with the aim of increasing injectivity. In wells L1 and L6 water was injected at high rats to hydraulically fracture the formation. On these wells acid injection was also carried out. The operations considerably increased short term injectivity (days); for longer period (weeks-months) no significant improvements were observed on wells L1 and L6. A stress analysis model was used to understand better the phenomena induced by hydraulic fracturing with the injection of cold water in a formation with temperatures of 200°C. This made it possible to explain why the artificially created fractures did not close completely at the end of stimulation. On well L14 matrix acidizing was performed with the aim of combating the strong skin effect present. In this case a notable increase in injectivity was achieved.