RU2167272C2 - Method of supplying reagents into flowing gas-condensate well - Google Patents

Abstract

FIELD: oil producing industry; applicable in supply of corrosion inhibitor into flowing wells for protection of pipes from corrosion. SUBSTANCE: method involves regulation of passage time of reagent through annular space for formation of protective film. Time of passage of reagent is regulated by injection of displacing fluid. Amount of reagent is determined by its total consumption for formation of protective film on internal surface of casing pipes. Total consumption value includes losses for dissolving and mixing of reagent with formation products, with its subsequent withdrawal from well. Time of reagent passage along annular space shall not be less than that required for formation of protective film on internal surface of casing string and on external surface of tubing string. Time of reagent passage through tubing string together with carried from bottom-hole formation shall not be less than that needed for formation of protective film on its internal surfaces. Time of reagent passage through tubing string is regulated by volume of withdrawal of formation products. Density of mixture of formation products and reagent shall not exceed rated value. EFFECT: reduced consumption of reagent, prevented spontaneous killing of well in injection of corrosion inhibitor into flowing gas-condensate well.

Description

 The invention relates to the oil and gas industry and is intended for supplying corrosion inhibitors to flowing gas condensate wells to protect pipes from corrosion.

 There is a method of constant uniform supply of a corrosion inhibitor to a well using a constant flow metering hydrostatic dosing unit [1], consisting of a working tank, a dosing device and a spare tank, the unit is assembled delivered to the well, mounted directly at the wellhead and connected with the annular annulus wells by impulse tubes.

However, this method with a constant supply of reagent has significant disadvantages:
- significant consumption of corrosion inhibitor;
- possible spontaneous killing of the well.

 The aim of the invention is to reduce the consumption of reagents and to prevent spontaneous killing of a well when injecting corrosion inhibitors into flowing gas condensate wells.

где
γ - удельный вес жидкости, кг/дм³;
P_пл - пластовое давление, кгс/см²;
H - расстояние от устья скважины до верхних отверстий интервала перфорации, м.This goal is achieved by the fact that in the method of supplying reagents to the annular (annular) space of the well, the advancement time of the reagent, for example, a corrosion inhibitor, in the annular space should not be less than the formation of a protective film on the inner surface of the casing and on the outer surface of the tubing and the time of advancement of the reagent along the tubing together with the production of the formation carried out from the bottom of the well should not be less than the time of formation of the protective film on their inner overhnosti. The time of advancement of the reagents in the annular space is regulated by pumping the injection fluid, and the time of its advancement through the tubing is regulated by the volume of production of the formation, while the specific gravity of the liquid in the well (mixture of product and reagent) should not exceed

Where
γ is the specific gravity of the liquid, kg / dm ³ ;
P _PL - reservoir pressure, kgf / cm ² ;
H is the distance from the wellhead to the upper holes of the perforation interval, m

 The method is as follows.

 Using a mobile pumping unit, the calculated amount of reagent (corrosion inhibitor) is determined into the annular (annular) space of the operating flowing gas condensate well, which is determined by the total consumption for creating a film on the inner surface of the casing pipes and the inner and outer surfaces of the tubing taking into account dissolution losses and mixing the reagent with the production of the formation with its subsequent removal from the well.

 The injected reagent, having a specific gravity greater than the production of the formation (carbonated oil, gas condensate, etc.), hydrostatically moves along the annular space to the bottom of the well, forming a protective film on the inner surface of the casing pipes and the outer surface of the tubing. Upon reaching the lower end of the tubing, the reagent is picked up by the flow of formation products and carried to the surface, forming a protective film on the inner surface of the tubing and wellhead equipment.

 The time of advancement of the reagent in the annular space should be at least the time of creation of the protective film on the inner surface of the casing pipes and on the outer surface of the tubing. This time can be adjusted by pumping the filling (squeezing) fluid into the annular space of the well.

 The time of advancement of the reagent along the inner cavity of the tubing should be at least the time of formation of the protective film on the inner surface of the latter and is regulated by the volume of production of the formation.

 As is known, during technological operations in flowing production wells with a low specific gravity of reservoir products, their spontaneous killing may occur, i.e. the termination of its flowing due to the filling of the formation with a reagent fluid with a specific gravity significantly exceeding the specific gravity of the well production. If the specific gravities are equal, an unstable equilibrium state is created.

где
γ - удельный вес жидкости, кгс/дм³;
P_пл - пластовое давление, кгс/см²;
H - расстояние от устья скважины до верхних отверстий интервала перфорации, м.Therefore, the specific gravity of the liquid (a mixture of reagent and product) should not exceed the specific gravity that ensures the equilibrium of the system, and is determined by the formula

Where
γ is the specific gravity of the liquid, kgf / dm ³ ;
P _PL - reservoir pressure, kgf / cm ² ;
H is the distance from the wellhead to the upper holes of the perforation interval, m

 Types and forms of preparatory work for cleaning the surface of pipes before carrying out a technological operation for reagent injection, as well as the frequency of injection and reagent consumption, are not considered in the application materials and are determined by regular work plans for a particular well and specific corrosion inhibitors.

 The proposed technical solution has been tested and implemented in oil fields of the Orenburg region.

Sourse of information
(1) 1776297 A3 (UKRAINIAN RESEARCH INSTITUTE OF NATURAL GASES), 11/15/1992.

Claims (1)

A method of supplying reagents to a flowing gas condensate well, including pumping a calculated amount of reagent into its annular annulus and adjusting the time of reagent advancement through the annular annular space by injecting a squeezing fluid to create a protective film, characterized in that the calculated amount of reagent is injected into the annular annular space with taking into account its total consumption for the creation of a protective film on the inner surface of the casing pipes, internal to it and the outer surfaces of tubing, including loss of dissolution and mixing of the reagent with the production of the formation followed by its removal from the well, while the time of advancement of the reagent along the annular annular space should not be less than the time of formation of the protective film on the inner surface of the casing and on the outer the surface of the tubing, and the passage time of the reagent along the tubing together with the formation products taken from the bottom of the well should not be less than about transform of the protective film on their inner surface, with the advance of the reagent of the tubing is adjusted sampling volume reservoir production, and the proportion of mixture formation and reactant product should not exceed values

where γ is the specific gravity of the mixture of formation products and reagent;
P _PL - reservoir pressure;
H is the distance from the wellhead to the upper holes of the perforation interval.