New deposit depths have to be developed to scale up gas extraction in Ukraine
“In the past three years our company drilled 13 deep wells ranging from 5.5 to 6.75 thousand meters. Each of these projects was unique in terms of project management, technological solutions, and equipment. If we want to step up the gas production nationwide, the projects of this kind have to be made widespread. For this, investment environment capable of fostering competition between technologies both in terms of scope and cost has to be created in Ukraine,” noted Oleksandr Lazarenko.
Naftogazvydobuvannya representative cited sidetracking operations at well no. 71 of the Semyrenkivske Field performed in cooperation with Weatherford, a global service company, as an example of new technologies and experience. The technological operations aimed at enhancing performance of the well was carried out at the depth of 5,033 meters. As of today, this is the deepest sidetrack in a casing string with a diameter of 245 mm in the world.
The company succeeded in achieving high drilling speed by applying modern drilling bits. For instance, during the construction of well no. 23 at the Semyrenkivske Field, a 3,707-4,991 m interval (1284 m) was driven through with one drilling bit that had average mechanical speed of 5.01 m/hour. Earlier, almost nine drilling bits were required to complete works of similar complexity due to complicated mining and geological conditions, and the average mechanical speed was manyfold lower.
The company reached good-quality penetration of a producing reservoir, which is a prerequisite for an optimal well flow rate, by using biopolymer drilling mud that has unique properties and thermal resistance characteristics. Such mud allows creating high resistance for preventing filtrate invasion at high temperatures of 150°C and higher.
Well design was improved as well. Changes provided an opportunity to minimise a risk of drilling problems. Filters used for well completion improved the performance of wells and prevented the contamination of formation with cement slurry. Also, to increase the service life and reliability of its wells, Naftogazvydobuvannya started using 13 Cr stainless steel production strings.