RU2095543C1 - Method for treatment of down-hole zone of well - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: this can be used for isolation of water inflows and beyond-string overflows from upper-lying water-bearing beds to lower-lying oil beds. According to method, well is partially filled with sand, but upper perforated holes are left free. Gel-formation composition is injected into down-hole zone of well, brine is pumped through and technological delay is realized during 1-2 days. Magnesium dispersion is prepared with brine. Magnesium dispersion is injected under pressure which is 30-40% higher than injection pressure of gel-formation composition. Second technological delay is realized during 1-2 days. Sand is removed from well and well is started for operation. EFFECT: high efficiency.

Description

 The invention relates to the oil industry and may find application in the isolation of water inflows and casing flows from overlying aquifers to underlying oil layers.

 A known method of fastening the bottomhole formation zone, including the injection of magnesium in the well and pumping of hydrochloric acid (1).

 The known method is not effective enough due to the fact that the fastening is carried out only due to the reaction products of magnesium with hydrochloric acid.

 Closest to the invention in technical essence is a method of attaching a bottomhole formation zone, including the injection of magnesium in a carrier fluid, followed by pumping with hydrochloric acid (2).

 The known method has low efficiency due to the separation at the bottom of magnesium and the carrier fluid and the creation of hardening of rocks at a small distance from the well.

 The invention solves the problem of creating rock fastening reliability along with isolation of water inflows from overlying aquifers into underlying oil strata at a considerable distance from the perforation holes of the well.

 The problem is solved in that in the method for processing the bottom-hole zone of a well, comprising injecting a magnesium dispersion, according to the invention, before injecting a magnesium dispersion, the well is partially filled with sand, leaving the upper perforations free, the gelling composition is pumped into the bottom-hole zone, the formation water is pumped and technological exposure is carried out in for 1 2 days, a magnesium dispersion is prepared on formation water, the magnesium dispersion is injected under a pressure of 30 to 40% higher than the injection pressure of the gelling composition a, carry out technological exposure for 1 to 2 days and remove sand from the well.

 The essential features of the invention are: Filling the well with sand to the upper perforations; injection of a gel-forming composition into the bottomhole zone; formation water pumping; technological exposure for 1 2 days; preparation of a dispersion of magnesium in produced water; magnesium dispersion injection; the injection pressure of the magnesium dispersion is 30 to 40% higher than when the gel-forming composition is injected; the second technological exposure for 1 2 days; sand removal from the well.

 Sign 6 is common with the prototype, signs 1 5 and 7 9 are the essential distinguishing features of the invention.

 SUMMARY OF THE INVENTION During the operation of the well, the adhesion of the cement ring to the rock or casing of the well is broken and channels arise for the passage of water from the aquifers to the perforation interval. In the case of a multilayer reservoir, a part arises when the aquifers are located above the oil ones. The isolation of such aquifers is particularly difficult. The proposed invention solves the problem of isolation of aquifers located above the perforation interval, as well as the fastening of the cement ring and rocks. To solve this problem, the well is filled with sand, leaving the upper perforation openings having hydrodynamic connection with the overlying aquifers uninspected. Filling the bottom perforations, as it were, temporarily isolates them from the impact from the side of the well. When the gel-forming composition is pumped, it enters into the unspoiled upper perforations and is pressed into the channels communicating with the upper aquifer. With a sufficient volume of the composition and when pumping formation water, the gelling composition reaches the aquifer and is structured there, creating tampons. With the subsequent pumping of the magnesium dispersion, the pore channels are filled with magnesium. After the reaction of magnesium with produced water, a dense, durable layer of magnesian cement appears, which prevents the swab from being squeezed into the well. Reliable isolation of water inflows is created. After operations, sand is removed from the well by washing or, if necessary, by drilling and washing. As a result, the water cut of the produced products is reduced.

 Examples of specific performance.

 Example 1. Processed at the bottomhole zone of the well with a depth of 2250 m. The well is filled at 50 m with sand to the upper perforations, the gel-forming composition is injected into the bottomhole zone through the upper perforations, including 0.5 kg of polyacrylamide, 0.15 kg of potassium dichromate, 0, 2 kg of lignosulfonate and 99.15 kg of water. The injection volume is 200 m, the injection pressure at the mouth is 9 10 MPa. Pumped formation water in a volume of 4 m and spend technological exposure for 1 day. A magnesium dispersion with a particle size of up to 1 mm in the produced water is pumped. The dispersion of magnesium contains 35 kg of magnesium per 1 m of water. The injection volume of magnesium dispersion is 15 m, the injection pressure is 13 14 MPa. Spend technological exposure for 1 day. Sand is washed from the well and the well is put into operation.

 Example 2. Perform as example 1. The volume of gel-forming composition of 300 m. The volume of pumped formation water 5 m. Technological exposure 2 days. The dispersion of magnesium contains 50 kg of magnesium per 1 m of water. Dispersion injection volume 40 m. Technological exposure 2 days. Sand in the well is drilled and washed.

 Example 3. Perform as example 1. The injection volume of the gel-forming composition is 100 m. The volume of pumped formation water is 3 m. Technological exposure is 1.5 days. The dispersion of magnesium contains 20 kg of magnesium per 1 m of water. Dispersion injection volume 10 m. Technological exposure 2 days. Sand in the borehole is washed out.

 The application of the proposed method will reliably isolate the overlying aquifers from the underlying oil bearing layers and thereby reduce the water cut of the produced products by 15 30%

Claims (1)

 A method of treating a bottomhole zone of a well, including ejecting a magnesium dispersion, characterized in that before injecting the magnesium dispersion, the well is partially filled with sand, leaving the upper perforation holes free, a gelling composition is pumped into the bottomhole zone, formation water is pumped and technological exposure is carried out for 1 2 days, a magnesium dispersion is prepared on the produced water, the magnesium dispersion is injected at a pressure of 30 to 40% higher than the injection pressure of the gelling composition, and the technological exposure for 1 2 days, remove sand from the well and start the well into operation.