Technological Developments in Deep Drilling in the Larderello Area

Abstract

The most recent technological developments in the deep drilling of geothermal wells in the Larderello area are described in this paper.
Environmental compliance of the drilling operations has been enhanced by means of noise reduction through soundproofing of the drilling rig and associated equipment; moreover, significant advance was made in the reduction and recycling of the debris produced.
New techniques for plugging absorbing zones have been used, coupled with modified cement slurries, with consequent substantial improvement of the casing cementing works.
Corrosion-resistant casing materials are being used near and up to the wellhead, as well as wellhead coated components, so as to insure an extended life in presence of steam containing acid-chlorides. Steam scrubbing may thus be carried out at wellhead, instead of down hole, even at moderate steam superheating conditions.
Finally, the drilling of multilateral wells with the use of retrievable whipstocks was recently tested with success in highly demanding well conditions. This technique will prove very useful in reducing the cost of drilling in low-permeability reservoirs.