Elimination of sticking of the drilling tool


In the process of drilling, complications associated with sticking of drilling tools occupy a large percentage of the time compared to other accident and require a large amount of time to eliminate them. 
Clamps tool occur for many reasons, the main ones are: 
1. Adhesion of the tool to the borehole walls while leaving him without movement;
2. Torque due to formation of glands and contraction of the wellbore as the result of a buildup of thick crusts;
3. The collapse of unstable rocks;
4. The wedging of the tool during the descent, the drilling or study of a full-size drill bits;
5. Jamming and sticking of the tool in the grooves;
6. The wedging tool as a result of entering into the wellbore obstructions;
7. Stuck pipe caused by the gas-oil-water seepage and acquisitions;
8. Sticking due to deposition of cuttings.

The main interest in the sticking tool (more than 50%) is the adhesion of the tool to the borehole walls while leaving it without movement. To determine the causes of this phenomenon there have been numerous laboratory and field experiments, in which it was determined that this process mainly affected by two factors: the stickiness of the clay crust and the hydrostatic pressure in the area of sticking. 
The adhesion of clay particles to the surface of the pipes can be explained by the formation on the surface in pipes and particles of clay mud of the forces of electrical attraction, depends on the availability at the interface of the free layer and the electric charge of particles. If the surface of the drill pipe will not come into contact with the solution and with the clay crust, the forces of adhesion between the pipe and the cork will be much more than between the pipe and the film mud. This is because the clay particles in the cortex have a thin water shell, more closely located to each other, and therefore, the force of electric attraction between the pipe surface and clay particles with thin shells, manifest themselves more vigorously. At the same time, the more the drilling mud is a colloidal phase, the higher the stickiness of the clay cover. For example, when content in the solution over 10-20% of the colloidal phase, the viscosity of the crust increases several times. By increasing the density of the solution, the stickiness of the crust also increases with increasing solids content. But the increase in mud weight leads to an increase in hydrostatic pressure in the well, which increases downforce, aimed at pressing the drilling tool to the borehole wall. This phenomenon is particularly observed at autopsy permeable strata when the borehole wall is formed thick clay crust and, under the influence of pressure drop in the system well-layer, the sticking of the drilling tool in differential sticking. In this case, at rest, the amount of sticky mud cake can reach 0.5-0.8 kg/cm2 or more. In terms of stickiness, to release the stuck tool must be applied to each 1m2 tack-welded pipe 5-8T load, which in most cases is not possible due to limitations of the carrying capacity of the rig. 


Accordingly, to prevent sticking of drilling tools is necessary to take the following actions: do not leave without movement of the drill string and to use a drilling mud with small solids and colloidal phase having a high antifriction properties. To eliminate the sticking, you need to create a layer between the drill string and mud cake or break the clay crust.
There are different ways of liberation from sticking. Basically, at the beginning of the production of such works, installing oil bath with being tool. In some cases, these works bring a positive result, but not always. If oil fails to penetrate into the space between the clay crust and the drilling tool or the tool is stuck at a significant site, then extract the tool will fail. Also, in some cases there are limits on the density of the bath when the incision is reservoirs with high pressure and there is the probability of obtaining the manifestations.

To solve this problem, we proposed the use of an aqueous solution responsereader reagent PP stamps D.

Technology responisble aimed at the destruction of clay particles. The technology uses an aqueous solution responsereader special composition, which does not affect the metal columns, but effectively destroying the clay particles. The reaction mechanism was the effect on the crystal lattice of the clay particles, while there is a weakening of structural bonds, resulting in the destruction of clay particles, after which the latter is incapable of peptization and seal and easily carried out under the stuck pipe string. 


Experimental work on the elimination of stuck pipe were conducted at the wells, drilling of which carried crews of OOO Leninogorskneft" in the fields of JSC "Tatneft". We have carried out work on three wells where traditional methods (setting of the oil bath) stuck to liquidate failed. 


14 Mar 2011 well No. 701 Berezinsky lifting when lifting the BHA in the range of 440-460m has any sticking of the drilling tool, torque was up to 38тн during unloading of landing to - 0тн. Being the stuck tool with a hook load - 25tn and unloading to - 0тн, flush with the clay solution, technical water and setting the oil bath to no avail. 15марта 2011 at 17.40, made a first fix portion responsereader reagent PP in a quantity of 360кг (V-3. 6m3). After 2 hours, was added a second portion responsereader reagent PP in a quantity of 360кг (V-3. 6m3). When being stuck tool, with hook load - 25tn, with unloading to - 0 t, 22.40 freed tool.

11 Jul 2011 during the drilling of well No. 526Д occurred sticking of the drilling tool in the range of 700-860m. Installation of an oil bath with being the drilling tool gave no results. 12 Jul uploaded 300kg (3,0m3) aqueous solution responsereader reagent PP for 3 hours eliminated the sticking.

21 October 2012, with the elimination of absorption at well No. 4848 Beslanskogo field, there was a sticking of the drilling tool. Washing with the BHA being and attempt rotation of the rotor with a total weight of BHA 27-28тн to 55-60тн the result is not given. Made a fix of commercial oil /=5M3. Parking under a bath of oil, with BHA being the total weight of BHA 27-28тн to 60 65тн the result is not given. October 22, at 15.00 in the well was added a solution of responsereader reagent PP in the amount of 400kg (4,0m3). In the reaction process were being BHA with a total weight of BHA 27-28тн to 60 65тн. Exemption from sticking at 18.10.

Conducted work on the application responsereader reagent RR grade D showed that:

With the use of responsereader reagent RR grade D there is a sharp reduction in the time of the liquidation of such complications as differential sticking.
This technology eliminates the use of oil for the installation of oil baths.
Responsiveui reagent PP is a dry powder with a long shelf life that allows you to create drill emergency reserve and use it as needed like the elimination of stuck pipe, and for development wells.

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