CEMENTING METHOD FOR WELL WITH ABNORMALLY LOW RESERVOIR PRESSURE Russian patent published in 2008 - IPC E21B33/14 C09K8/40 C09K8/473 

FIELD: oil and gas well production, particularly to cement surface casing and producing well with abnormally low reservoir pressure.

SUBSTANCE: method involves serially injecting buffer fluid, plugging cement mix, aerated plugging cement mix and displacement fluid in well. Buffer fluid includes neonol-based foam generator in amount of 3-4% by weight, chemical reagent in amount of 2-3% by weight, nitriletrimethylphosphonic acid in amount of 0.2-1.0% by weight, remainder is water. Said buffer fluid is aerated or saturated with inert gas and injected in well. The plugging mix is solution with increased isolating ability having density of 1810-2000 kg/m³. Plugging mix contains (in parts by weight) Portland cement - 100, chemical reagent used in buffer fluid - 0.1-0.5, calcium chloride or aluminum sulfate - 2.0 and water - 48-50. In the case of surface casing cementing the injection is carried out in the following order: solution with increased isolating ability, solution with increased isolating ability saturated with air or inert gas up to density of not more than 1200 kg/m³. In the case of producing string cementing first of all solution with increased isolating ability is injected, then solution with increased isolating ability saturated with air or inert gas up to density of not more than 1300 kg/m³ is fed and finally solution with increased isolating ability is injected. Displacing fluid is supplied at the rate of 15-60 m³/hour.

EFFECT: increased efficiency.

4 ex, 1 tbl