RU2006145527A - METHOD FOR CEMENTING A CASING OF A GAS WELL IN CONDITIONS OF PERENNIAL PERFORMANCE - Google Patents

Claims (2)

1. A method of cementing a casing string of a gas well under permafrost (MMP) conditions, including lowering a casing string equipped with a TsKOD type check valve without a shut-off element below the MMP zone, pumping buffer fluid into the casing, the first portion of cement, removing drilling mud from the annular space by forcing the first portion of the cement mortar with squeezing fluid through the shoe of the column to the wellhead, pumping the second portion of the cement mortar into the annulus the environment from the wellhead to the start of setting the first batch of cement with simultaneous control of the pressure in the casing space at the wellhead, leaving the well waiting for cement to harden, characterized in that aerated cement slurry is pumped into the casing with a degree of aeration at the bottom wells 0.2-0.4 in the following ratio of ingredients of non-aerated cement mortar, wt.%: Grouting Portland cement 68.23-70.62 Superplasticizer S-3 0.34-0.49 Sulfonol 0.57-0.69 Polypropylene fiber 0.04-0.07 Water 28.25-30.70 and as the first portion of the cement mortar, the composition is pumped in the following ratio of ingredients, wt.%: Portland cement type 1-G 69.4-69.9 Polypropylene fiber 0.04-0.07 Water 30.06-30.53, moreover, the first portion of the cement mortar is pumped in the amount necessary to fill the annular space in the interval from the bottom of the well to the roof of stable clay-sandy rocks in the IMF zone, and when the first portion of the cement mortar is squeezed with squeezing fluid, the density of the fluid leaving the well is additionally controlled, and if its density of the cement slurry injected into the well matches, the punching is stopped, the maximum pressure at the wellhead and the volume of injected augmented fluid, then a locking element is thrown into the casing - a ball, after which a second portion of cement mortar is pumped into the annulus from the wellhead in a volume calculated by the formula V = V _{sn RV} -V _k where V _VP - the volume of the second portion of the cement mortar, m ³ ; V _pzh - the volume of pumped squeezing fluid for forcing the first portion of the cement mortar, m ³ ; V _to - the volume of the column space from the wellhead to the top of the cement cup, left in the column, m ³ ; while providing pressure at the wellhead in the casing by throttling that satisfies the condition (1-h / L _o ) P _p <P _y <P _p , where R _p - pressure on the pumps at the time of completion of the forcing of the first portion of the cement mortar, MPa; R _y is the pressure at the wellhead in the casing space when pumping a second portion of cement into the casing space, MPa; h is the installation height in the annular space of the first portion of the cement mortar, m; L _o - the depth of the casing, m stop pumping the second portion of the cement mortar and install a shut-off element - a ball in the check valve of the type TsKOD by pumping squeezing fluid into the column space with an open annular space. 2. The method according to claim 1, characterized in that the composition is used as the second portion of the cement mortar in the following ratio of ingredients, wt.%. Grouting Arctic cement "Arcement" 66.7-68.9 Water 31.1-33.3