Tremendous savings in drilling investment have been made possible through application of a new drilling concept and directional system. The Straighthole Drilling Device (SDD) has migrated from an experimental system into a mature tool, which is now used to a major economic advantage in different places of the world. At first sight this device's advantage seems to be mainly the ability to drill a borehole into the ground with a vertical trajectory. However soon after the earliest applications in a commercial environment it became obvious, that this new kind of directional tool allows in fact to revolutionize the way of drilling.
Much beyond the mere benefits of a straight and geometrically exact borehole shape, SDD technology actually offers the opportunity to completely re-configure the well trajectory. The final result of this are considerable savings in time and investment to arrive to well production. According to the current knowledge base, the SDD is also be extremely helpful in locations, were the formation has a natural tendency to build up hole inclination.
SDD has been used in several different hole sizes, there providing a higher penetration rate, and a very smooth and precise hole trajectory. This in turn allows to drill wells in a cluster approach, and to apply the lean casing concept. Also curved sections in the lower part of the hole do considerably gain with respect to lower friction in the drill string to borehole wall contact. Finally, a considerable positive environmental impact is associated with this technique, in terms of reduction of waste disposals at about 30% in volume, compared to a standard well profile.
Basically the SDD comprises a positive displacement motor section, a control sub having electronic and hydraulic means, and a bearing assembly equipped with selectively expandable stabilizer pads. The system does autonomously drill a straight, vertical hole, where no surface human interaction is required. Whenever the directional sensors detect any small deviation from the vertical, one or more of the ribs will be activated in a closed loop circuit. Standard mud pulse transmission allows to monitor the down hole operation.
SDD was originally developed for the German Scientific Ultra-Deep Well (KTB), but later on turned out to be of considerable advantage for major oil and gas fields in Italy. SDD has so far seen it's most utilization in South of Italy, which is the center of Italy's onshore oil and gas exploration. Meanwhile additional application has occurred in other places around the Mediterranean Sea. A considerable interest has recently developed within several drilling areas in South America.