WEIGHTED GROUTING GYPSUM MIXTURE Russian patent published in 2012 - IPC C09K8/42 

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas industry, and namely to weighted grouting gypsum mixture used during repair and abandonment of wells under conditions of salt-bearing deposits in presence of hydrogen sulphide. Mixture includes binding agent: calcium sulphate, fluid for pre-mixing in the form of salt solution, additive - hardening agent like fine-grained mineral substance Mikrodur-2611C and adjusting agent of processing properties - nitrilotrimethylenephosphonic acid. Barium sulphate is used as hardening agent, and superplasticising agent C-3 is used in addition as adjusting agent of processing properties at the following component ratio, wt %: calcium sulphate 31.6-48.7; barium sulphate 9.7-31.6; Mikrodur 1.6-6.8; superplasticising agent C-3 0.14-0.45; nitrilotrimethylenephosphonic acid 0.025-0.1; and salt solution is the rest. As salt solution there used is solution of potassium chloride, or calcium chloride, or calcium bromide, or their mixture, with density of 1.0 to 1.7 g/cm³.

EFFECT: improving insulation efficiency; enlarging manufacturing capabilities of mixture; increasing service life of grouting mixture.

2 cl, 1 tbl, 1 ex