RU2032067C1 - Method of sealing bed from water inflow - Google Patents

Abstract

FIELD: sealing boreholes. SUBSTANCE: protective liquid (PL), isolating material (IM) and cross-link agent (CA) are pumped in a borehole at an optimal pressing through speed under a given pressure and discharge. Each pair PL-CA uses aqueous solutions of alkali, soda-fluosilicic acid or calcium chloride-aluminum sulfate or potassium, sodium, ammonium bichromate-water glass. PL and CA are used in equimolar quantities. Selected PL and CA viscosity is less than viscosity of IM. Aqueous solutions of organic or inorganic gel-forming reagents are used as IM. On pumping CA selected pressing through speed must provide CA break through IM to PL. Further speed reduces up to the point providing PL break through IM layer to CA. EFFECT: enhanced efficiency. 2 cl

Description

 The invention relates to the oil and gas industry, in particular to methods for limiting water inflows in the production and alignment of the injectivity profile in injection wells.

 A known method of isolating the influx of formation water in the well, including the delivery of cementing material in the zone of water inflow and crushing it into the reservoir with a given optimal flow rate [1].

 The disadvantage of this method is that it applies only to homogeneous grouting compositions that cure in time due to formation water.

 A known method of isolating water inflows in an oil reservoir, including the sequential injection of a preservative fluid, an insulating material and a structural agent [2].

 The disadvantage of this method is its complexity in terms of the preparation of a preservative fluid based on oil, as well as the dosing and mixing of the components.

 The purpose of the invention is to simplify the process and improve the conditions for the formation of a water-insulating screen in fractured and permeable reservoirs that are sharply inhomogeneous.

 The goal is achieved in that in a method that includes injecting a preservative fluid, an insulating material and a structuring agent at a predetermined delivery pressure and flow rate, the optimal flow rate of a preservation fluid, insulating material and structuring agent into a formation is preliminarily determined depending on the selling pressure and their flow rate, while as a preservative fluid and structure-forming agent, one-component aqueous solutions are used, taken in an equimolar amount and forming a precipitate or low mobility contact gel, moreover, the viscosity of each of these solutions is chosen lower than the viscosity of the insulating material, and after injection of the structuring agent, the selling speed is set from the condition that breakthrough of the structuring agent through the insulating material to the preservation fluid, followed by a decrease in speed to a value that provides against preservative fluid through a layer of insulating material to the builder.

 At the same time, aqueous solutions of alkali, soda - hydrofluoric acid or calcium chloride-aluminum sulfate, or potassium, sodium, ammonium dichromate - water glass, and aqueous solutions of organic or inorganic gelling reagents are used as a preservative-structure-forming pair. .

 When a preservative fluid, an insulating material, and a structure-forming agent are pressed in the formation at a certain predetermined speed (flow rate), the latter breaks with dagger flows through cracks and highly permeable layers through a more viscous (less mobile) insulating material and reaches the preservation fluid, with which it instantly forms a sediment that inhibits further spread structuring agent, and it begins to penetrate in other directions from cracks, penetrate the insulating agent in the pores of the formation, yn screens on all sides by water inflow channel and along its cross section.

+ Si(OH)

+2H₂O В этой паре предохраняющей жидкости (раствор NaOH) и структурообразователя (H₂SiF₆) их соотношение должно быть как 6:1.To ensure the completeness and maximum rate of formation of inhibitory sediment, it is necessary to observe the equimolecularity of the ratio between preservative and structuring agents, for example
6NaOH + H ₂ SiF ₆ __ → 6NaF

+ Si (OH)

+ 2H ₂ O In this pair of preservation liquid (NaOH solution) and structure-forming agent (H ₂ SiF ₆ ) their ratio should be as 6: 1.

 The method is as follows.

 In a well prepared for isolation, the injectivity is determined at variable flow rates of fluid squeezed into the formation, the optimum feed rate of the material into the formation is found, and at this speed the preservation fluid, the insulating material and the builder are successively crushed.

 After all components have entered the reservoir (according to calculation), the pushing rate is sharply increased to a value that ensures breakthrough of the builder through the insulating material to the preservation fluid. This leads to inhibition of the builder and its distribution in different directions in the mass of insulating material, improving the conditions for their interaction and the formation of an insulating screen in the entire volume of the water inflow channel.

 With the subsequent change in the flow rate by depressurization and selection of the flowing liquid, the protective fluid breaks through the layer of insulating material and a precipitate forms on the other side of the insulating material, further limiting its mobility.

 The repetition of cycles selling - selection of the selling fluid leads to the formation of a tampon strictly in the zone of a highly permeable section of the reservoir.

 Tests of the method under industrial conditions showed an effective change (leveling) of the injectivity and flow profile in the formations using organic substances such as PAA, CMC, hypane, ethyl silicate, lignosulfonates, urea resins, latex, and inorganic, gel-forming compositions: water glass, silicofluorides, sulfates, etc.

 The method is applicable for producing wells while restricting water inflows of various nature and for injection wells when aligning the injection profile.

 In addition to high efficiency, the method is reliably controlled at all stages of the process by changing the injection pressure, which allows you to reasonably adjust the time of work and increase their productivity.

 The method is effective both in complex, heterogeneous reservoirs, and in fractured, carbonate formations with sharply uneven permeability.

Claims (2)

 1. METHOD FOR INSULATING A RESERVOIR FROM WATER DAMAGES, including injecting a preservative fluid, an insulating material and a structuring agent at a given displacement pressure and flow rate, characterized in that it is preliminarily determined the optimal rate of displacement of a preserving fluid, insulating material and structurant into the formation depending on the discharging pressure and their flow rate in this case, as a preservative fluid and structure-forming agent, one-component aqueous solutions taken in an equimolar amount and treated a sludge-forming or inactive gel upon contact with each other, moreover, the viscosity of each of these solutions is chosen to be lower than the viscosity of the insulating material, and after injection of the structure-forming agent, the selling speed is set from the condition that the structure-forming agent breaks through the insulating material to the preservation fluid, and then decreases the rate to providing a breakthrough of the preservative fluid through the layer of insulating material to the builder.  2. The method according to claim 1, characterized in that for each pair of preservation liquids - structure-forming agents use aqueous solutions of alkali, soda - hydrofluoric acid, or calcium chloride - aluminum sulfate, or potassium dichromate, sodium, ammonium - water glass, and in as an insulating material - aqueous solutions of organic or inorganic gelling agents.