Perm Journal of Petroleum and Mining Engineering (Sep 2015)
Results of applying acidic hydraulic fracturing with proppant in the Tournaisian-Famennian reserves at the Ozernoe field
Abstract
The paper is devoted to the efficiency of acidic hydraulic fracturing – the most widespread method of well stimulation for the Tournaisian-Famennian carbonate reserves found in the Ozernoe field. All the operations performed may be divided in two groups: acidic hydraulic fracturing performed by the conventional technology when fracture openness is reached by wall profile following the reaction of acid with rock, and acidic hydraulic fracturing with proppant. At the site investigated 12 operations of proppant fracturing were performed. To assess the results, including comparison with the conventional acidic hydraulic fracturing, the well investigation data were obtained under nonsteady flow before and after the treatment. In doing so, pressure build up curves were processed by standard methods and that of Warren-Root to evaluate fracturing level. Two wells were chosen with similar production profile and formation flow characteristics prior to well intervention, which were explored twice afterwards. The reservoir was classified as porous for both wells in accordance with pressure build up curve. Following acidic hydraulic fracturing in both cases reservoir fracturing was observed with average fracture openness from 10 to 30 µm. However, nine months after the intervention no fracture were found in the well subjected to conventional acidic hydraulic fracturing, with the same formation flow and production characteristics as before the intervention. The well processed by proppant acidic hydraulic fracturing demonstrates fracturing immediately after the intervention and almost two years later, which testifies to the technology efficiency. The conclusions made were confirmed by field data.
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