Method for isolating penetrable beds in a well

The invention relates to the construction of oil and gas wells, in particular to the isolation of permeable formations, as in drilling and overhaul.

There is a method of isolation of the permeable formation comprising pumping into the well plugging material based on acrylic polymers and their derivatives [1]. These water-soluble polymers used in water compositions in combination with electrolytes, forming or precipitation (gels)or viscoelastic seal weight, stable in the environment of saline and fresh water.

However, the method has drawbacks. Cross-linked polymer in the process of leveling in the insulated layer passes through the pores streams and takes shape in the cross section, which further does not cause resistance to the interaction of water sources nearby reservoirs. In addition, this method consistently pumped electrolyte, the polymer was then and again the electrolyte. When uneven porosity and permeability of rocks these components are not always fully involved in the reaction. Therefore, the output of the insulation material are low. Hence low efficiency and insulation works.

The closest technical solution chosen by the authors for the prototype is the way to isolate the permeable formation in a well comprising pumping portion swollen acrylic polymer AK-639 extract it in the well and the injection of the second portion of the same polymer.

This method has the following disadvantages.

When isolation of permeable layers of high-power and high pickup swollen polymer even when the concentration of the polymer of 20% goes into the depth of the reservoir and does not isolate the major channels in fractured and porous reservoirs

The objective of the invention is improving the efficiency and insulation works by providing fill fractured rocks, large canals in them grouting composition, limiting deep penetration swollen polymer in permeable reservoir rock.

The problem is solved due to the fact that the method of isolation of the permeable formation in a well comprising pumping portion swollen acrylic polymer AK-639, extract it in the well and the injection of the second portion of the same polymer, before and after injection of the first portion of the swollen polymer shut on fresh water with a concentration of 1-20%, is pumped buffer of fresh water, and before and after injection of the second portion swollen polymer shut on a hydrocarbon liquid with a concentration of 10-20%, they fill the buffer from the hydrocarbon liquid, additionally, the well pumped mentioned 2 portions of the system repeatedly.

Essentially with this method the problem is solved due to the following additional mechanism for the formation.

Swollen polymer satoren the first hydrocarbon fluid, inert. Therefore, it penetrates into large cracks, simultaneously plugging the inlet of small channels.

In large channels swollen polymer at some distance from the wells is mixed with fresh water. The polymer swells and covers a large channel, because it uses all its ability to swell in 100%. While the injection of swollen polymer shut on fresh water, he at the approach to the insulated interval loses up to 50% of its capacity to swell.

Example of commercial application of the method:

For carrying out insulation work in a well drained column tubing (tubing) to the roof of the insulated layer.

The layer presents srednetsenovoj breed.

For isolation of the reservoir in the casing at the closed annulus is pumped buffer of fresh water and is determined by the injectivity of the well.

Then closes the first portion of the swollen polymer in fresh water and pumped into the well. After that pumped buffer of fresh water.

The second portion of the swollen polymer is prepared in the following sequence: injection buffer of the hydrocarbon fluid, the swollen polymer, shut hydrocarbon fluid, a buffer from the hydrocarbon liquid.

In this sequence in the well for Aquatica several 2 portions of insulation systems if you have to isolate the reservoir, presents krupnosemyannye rocks.

In addition, when the insulation layers with high permeability, for example, more than 40 m³/h at a pressure at the wellhead of the order of 60-80 kg/cm²the concentration of swollen polymer in the oil increases due to the reduction of oil viscosity. For this purpose the oil is pre-injected surfactants, such as the brand "Neonol" 6 m³oil 9 l PAVA.

The proposed method differs from the known, which limited the effectiveness of the application in insulation works in permeable rocks, represented by large cracks or channels.

The advantage of the proposed method over the known is to ensure wide use of it in almost all ranges of permeabilities of rocks, as in the isolation of fractured carbonate rocks, and terrigenous. The method is equally applicable in cased and uncased wells.

Known technologically-not suitable for use with the elimination of water flows between reservoirs with different formation pressure, because the grouting mixture razbavlyali will be replaced, whereas the proposed method eliminates this process. A portion of the swollen polymer shut on hydrocarbon liquids when in contact with water will intensively to respond is due to the rapid structure formation to create a jumper with high bridging properties.

1. The method of isolation of the permeable formation in a well comprising pumping portion swollen acrylic polymer AK-639, extract it in the well and the injection of the second portion of the same polymer, characterized in that before and after injection of the first portion of the swollen polymer shut on fresh water with a concentration of 1-20% of the injected buffer of fresh water, and before and after injection of the second portion swollen polymer shut on a hydrocarbon liquid with a concentration of 10-20%, they fill the buffer from the hydrocarbon liquid.

2. The method of isolation of permeable formations in a borehole according to claim 1, characterized in that the well pump 2-batch system repeatedly.