Oil fields development practices indicate permeability degradation of reservoir formations in the bottomhole area at all development stages. Main reasons for this are the rock compaction in the bottomhole area due to hydrodynamic impact during well construction, swelling of argillaceous cement of reservoir formations, etc. To recover permeability to the initial values several methods may be applied, such as various types of acid and heat treatments, hydrofracturing, injection of surfactant and other chemicals.
Formation acid treatment significantly assists operators to maximize production on their fields. Demands in acid treatment technologies applied under high reservoir temperature conditions appear to a greater extend. During wells bottomhole area treatment with acid compounds the reaction and diffusion speed increase with temperature rise. This leads to speeding-up the reactions between acid and rocks what reduces the efficiency of treatment and may provoke other complications. To conduct bottomhole area treatment successfully it is necessary to have solutions on achieving the maximum required depth of penetration.
To resolve such complications in Vietsovpetro JV, in order to improve oil recovery from high temperature production wells, it was proposed the implementation of systems which assist in generating hydrofluoric acid in the formation.
Revealed, that the formation bottomhole area treatment method which assumes implementation of chelate compounds and ammonium biflouride which generate hydrofluoric acid in the formation bottomhole area during interreaction, is the simultaneous resolution of complications related to the high temperature and secondary sedimentation.
The proposed complex compositions for the bottomhole area treatment of high temperature wells allow for generating the hydrofluoric acid in the bottomhole area of the well. Complex consists of main treatment fluid made based on chelate compounds, buffering acid compound which pumped before the main treatment fluid and saline displacement mud.
References
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8. Ty Tkhan' Ngia, Le V'et Khay, M.M. Veliev, Nguen Kuok Zung, Issues related to the high temperature and secondary precipitation formation at the well bottom and ways to resolve it under Vietsovpetro JV conditions (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2015, no. 12, pp. 106–109.
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