Published February 2013

Complications in well cementation and their dissolution

D.S. Akhundov

Technological process of well cementation is defined by geological and technological factors. The distance between productive and pressure head water-bearing horizons influence the layers dissociation quality considerably. In the cases, when they are separated by small permeable interlayer, remaining against a crosspiece friable part of a clay crust easily breaks under the influence of pressure difference. Due to this reason, 20 % of wells give watered production. On Chararly, Lokbatan, Puta areas after production casing cementation while measurements via acoustic electro gauge, it was found out that the gearing among the productive series with cement stones is absent. The calculation shows, that the blacklash between productive series with cement stone depends on the well construction and isolation in a well cementation via oil-well portland cement against permeable rocks does not occur. While cement mortar hardens in annulus space, the cement volume decreases and it promotes the product absorption from the permeable series. As a result, the complications in the annulus space occur. In order to prevent these complications, it is necessary to apply expanding oil-well cement in cementation of wells against productive series. Large expanding value provides the pressure on well walls and casing, which furthers effective contact control on well wall, significant increasing of its stability and liquidation of annulus complications.