Published August 2010
Liquidation of complications in drilling wells in clay breeds
G.V. DzabbarovaThe basic part of the cut in drilling of oil and gas wells consists of clay breeds. These breeds consist of a number of various minerals, impurity and differ from other rocks specific properties from which the most important are plasticity, swelling ability, hydrophility, on mineralogical structure, a chemical compound and structure of a crystal lattice. On this in well drilling in clay breeds on areas Jahandar, tarsdallar, Naftalan, Jafarly, Michadkhanly, there was not one characteristic complication. The liquidation of these complications was conducted via different methods. One of the major factors influencing destruction of the well trunk is penetration of free water from a chisel solution between cells of clay particles of 5,5 . 10-8 sm setting down from each other on distance, it renders on them disjoining influence. Hydrated particles, being moved apart, increase system volume, clay bulks up. Coupling between clay particles is thus weakened, its durability decreases. As a result to pressure increase there is a clay swelling in a well trunk that leads to taluses and collapses. It is quite often accompanied with not bringing columns of boring pipes to the well face therefore occurs serious complications, failures. At such complications often in practice create additional back pressure on the showered layer, thus density of a chisel solution increase by 15%. After that in a current of 10-15 days hole sloughing breeds stops, with the expiration of this term intensity hole sloughing breeds increases also complication receive serious character. In clay muck at adsorption by water on their surface there is a hydration. As a result on a clay surface are formed hydrate ions with negative signs which are capable to accept cation. For this purpose in the chisel solution is added limy milk Ca(OH2) to the maintenance of ions of calcium of 300500 mg/l. Calcium ions take root into a crystal lattice of clay particles and on wells are formed calcic clay. This decreases hydrophility, physical and chemical properties change and durability of clay particles raises. The talus and a collapse of the well trunk are as a result prevented. With introduction of calcium ions in the well trunk in the crystal lattice one of the electric layers collapses. As a result of this, despite lone contacts of a column of boring pipes to clay breeds, in the absence of force of sticking does not occur.
