The purpose of cementing oil-well Portland cement - isolation from oil bearing strata, and the oil layer from each other. The methods of plugging wells include: direct cementing oil-well Portland cement, Portland cement grouting filling assembly, cementing Portland cement grouting through the fill tube, reverse cementing oil-well Portland cement, Portland cement grouting multi-casting, and others. The greatest distribution has received direct cementing oil-well Portland cement.
The basic requirements for quality Portland cement grouting are as follows. The slurry (slurry) portland cement grouting must have high fluidity to be easily and quickly pumped into the pipe string, and then to push it into the annulus. Portland cement grouting solution should remain mobile at all times while it is being cemented. Well Cement must be strong enough in the first two days after mixing. That is, after injection into the well of Portland cement grouting solution has the shortest time to acquire the necessary strength and keep it up to complete solidification and producing cement stone, which, in turn, must be resistant to aggressive groundwater, have some water-resistance and to be quite ductile that during the commissioning it does not crack formed. For gas wells also becomes relevant is the quality of the cement stone, made of Portland cement-based grouting is gas-tight. In this regard, the recent domestic industry began to develop, and special varieties of Portland cement grouting for oil and gas industry.
In addition to oil-well cements for hot or cold wells currently in production and universal Portland cement grouting and well cements intended for cementing in the special conditions of oil and gas wells (the so-called special Portland cement grouting with a fairly narrow field of application). For example, lightweight backfill Portland cements produced in the same manner as the other Portland cement plugging, but facilitate use of special additives (pumice flask, tripoli). These lightweight backfill Portland cement are produced as well for hot and cold weather.