SU640023A1 - Method of heat and chemical treatment of hole bottom area - Google Patents

Description

one

The invention relates to the oil industry, in particular to secondary methods of influencing a formation by treating its bottomhole zone.

There is a method of treatment of the reservoir by exposure to hydrochloric acid 1.

Due to the rapid reaction of the acid with the rock, the method is not effective enough.

The known method of thermochemical treatment of the bottomhole formation zone by pumping metallic magnesium into it, followed by the injection of hydrochloric acid solution 2.

The method is not effective enough due to the low temperature of the warm-up zone.

The aim of the invention is to increase the treatment efficiency by increasing the degree and duration of the warm-up zone of the formation.

This is achieved by the simultaneous injection of ammonium nitrate into the reservoir along with magnesium.

The method is carried out as follows.

Ammonium nitrate is mixed with granulated magnesium or its sawdust in hydrocarbon-based fluids and the mixture is fed into the formation. Hydrochloric acid is then injected into the formation.

Improving the efficiency of thermochemical treatment of the bottomhole formation zone is achieved by obtaining nitric acid directly in the bottomhole formation zone during decomposition of ammonium nitrate. The initiator of the decomposition of ammonium nitrate is the high temperature obtained by the reaction of magnesium with hydrochloric acid. The production of nitric acid is according to the reaction.

4NH4NO3: 3N2 + 2NO2-f 8H2O +

+ 29.5 kcal / mol

2NOj + H, O HNO3-fHNO.,

3HNO2 HNO3 + 2NO + HjO.

In this case, each gram molecule of ammonium nitrate gives 29.5 kcal of heat to 1/3 of the molecule of nitric acid, the concentration of which averages 15.5%. Magnesium, hydrochloric acid, water vapor and oxides of nitrogen serve as catalysts for the decomposition reaction. 1 kg of ammonium nitrate gives about 350 kcal of heat. It is very important that the mixture of nitric and hydrochloric acids transfers into solution all products of the initiating reaction of magnesium with hydrochloric acid, as well as sparingly soluble salts in hydrochloric acid, and thus prevents the formation of filtering products from the surface and provides cleaning them from the deposited salts. A very aggressive mixture of salt and nitric acid, yitrosyl chloride, is obtained by means of it in the bottomhole zone of the reservoir, which prevents destruction of the field and well equipment and its 100% utilization of the bottomhole formation. Obtaining additional heat during the decomposition of ammonium nitrate increases the total amount of heat, and the released nitrogen lengthens the time of separation with the release of teila, which contributes to a better melting of asphalt-resinous substances and paraffin in the near-bottom zone of the reservoir and the zone of penetration of the irio-bottom zone of the formation increases. The resulting nitric oxide reacts with the hydrogen produced by the reaction of magnesium with hydrochloric acid. The combination of equal volumes of hydrogen with nitrogen oxide at those temperatures that occur during the above described reactions in the bottomhole zone results in an explosion with the release of a large amount of heat.

2NO + 2H,., + 2H2O4-159 kcal.

In order to achieve the maximum thermal effect, it is necessary to choose a ratio between the amount of magnesium and the amount of ammonium nitrate so that all the hydrogen produced by the binding of magnesium is combined with the released oxide of nitrogen. Theoretically, the ratio is as follows: there are 6 ammonium nitrate molecules per 1 magnesium molecule. The released free nitrogen slows down the reaction of the acids with the rocks, which allows the more distant zones of the formation to be treated. When a depression is created on the reservoir to call in the inflow after treatment of the well, the bubbles of free nitrogen either widen or then create conditions for partial destruction of the reservoir rocks and detachment from the surfaces of cracks and pores of various sediments and bringing them to the bottom of the well. With an increase in the magnitude of deyressinsa reservoir, this effect increases. In addition, free nitrogen in the process of commissioning a well aerates the fluid and facilitates well development. In the carbonate reservoirs, the processing of the bottomhole zone does not require the injection of coarse sand, since the formation cracks are spread by leaching calcium and magnesium carbonates, increase in volume and usually do not close after the load is removed.

Preliminary studies and calculations show that to treat a single well with a reservoir thickness of 10-15 m, a mixture of the following composition must be pumped into the reservoir: granulated magnesium from 20 to 250 kg, ammonium nitrate from 100 kg to 10 tons or more, hydrochloric acid from calculating at least 20 liters of 15% concentration per 1 kg of magnesium, coarse sand up to 10 tons or more, hydrocarbon-based liquids, such as oil, condensate, etc., up to 10 liters per 1 kg of the mixture.

Claims (2)

1. Authors certificate of the USSR 289194, cl. E 21B 43/27, 1969. 2. USSR author's certificate number 467173, cl. E 21B 43/27, 1973.