METHOD FOR THE COMBINED APPLICATION OF SCALE REMOVER AND INHIBITOR

Abstract

The invention is related to a joint application process of two treatments, scale removal and inhibitor squeeze injection. Through the simultaneous positioning inside the reservoir, it can be applied in scale removal operations for carbonate formations, such as the pre-salt case. Accordingly, there is a way to improve the efficiency of reservoir management, through an innovation in the scaling management process.

Claims

1- A METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR, characterized in that it comprises the following steps: a) Preparing the scale remover solution; b) Preparing the scale inhibitor squeeze solution; c) Mixing the previously prepared solutions, forming a single solution; d) Injecting the mixture into the reservoir at a temperature of 60° C., using water produced from the well, with a calcium content ranging from 2,080 to 20,000 mg/L, to provide simultaneously the removal of scale followed by the inhibition of the reservoir rock.

2- THE METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR according to claim 1, characterized in that the removal solution is any acids, preferably acetic acid, formic acid and hydrochloric acid.

3- THE METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR according to claim 1, characterized in that the scale inhibitor is one of the types of products that have the same active principle based on compounds derived from phosphonic acids with general formula RP(O) (OH).sub.2, and can present different numbers and types of phosphonic groups, (di, tri, tetra and penta), with different concentrations of active matter.

4- THE METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR according to claim 1, characterized in that the scale inhibitor is in the concentration range between 10 to 20 mg/L.

5- THE METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR according to claim 1, characterized in that the scale inhibitor is at a concentration of 10% v/v diluted in 2% m/v KCl solution.

6- THE METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR according to claim 1, characterized in that the scale inhibitor is at a concentration of 20% v/v diluted in 15% HCl solution or 10% acetic acid.

7- THE METHOD FOR JOINT APPLICATION OF SCALE REMOVER AND INHIBITOR according to claim 1, characterized in that the proposed treatment to combine triple function, reservoir stimulation, scale removal and inhibition, mainly by matrix acidification and consequent distribution of the inhibitor cushion mainly in heterogeneous and reactive reservoirs.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0019] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

[0020] FIG. 1 illustrates a representative view of the stationary production unit, stimulation boat, coflexip line, production line, gas lift line, wet Christmas tree, production string and the reservoir;

[0021] FIG. 2 illustrates a representative view of pumping the acid solution together with the scale inhibitor, from the stimulation boat through the coflexip line to the stationary production unit, and from there through the production line to the wet Christmas tree, and from there through the string to the reservoir;

[0022] FIG. 3 illustrates a representative view of the opening of the well, after the programmed time of contact of the acid with the reservoir, for the removal of spent acid from the reservoir and simultaneously the fixation of the inhibitor in the reservoir rock, the spent acid rises through the string, passes through the wet Christmas tree and goes through the production line to the stationary production unit where it will be processed.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention addresses to a method for the joint application of two treatments, that is, the one for scale removal, and/or reservoir stimulation; and the inhibitor squeeze injection. The removal and/or stimulation of the reservoir can be by the removal solution being any acids, preferably acetic acid, formic acid and hydrochloric acid. With the use of a stimulation boat (2), positioned on the sea level (12) in parallel with the stationary production unit (1), connected to the stationary production unit (1) by a coflexip line (5), to pump the mixture of acid and inhibitor through the stationary production unit (1) following the production line (3) or the gas lift line (4), both are immersed in the water layer (13), up to the wet Christmas tree (6), which is positioned in the mud line (11), where the mixture of acid and inhibitor accesses the well, following the production string (7), for the simultaneous positioning inside the reservoir (8), where the mixture remains for a designed time that was planned based on the tests carried out with plugs of the reservoir rock, for the stimulation of the reservoir, for the removal of damage and for the inhibition of the reservoir (9); after the time programmed for the treatment, the well is open for production to the stationary production unit (1), then the mixture that was residing in the reservoir (9) is produced, leaving the inhibitor adsorbed in the reservoir (10), through the production string (7), passing through the wet Christmas tree (6), and from there to the production line (3) until arriving at the stationary production unit (1), where the mixture and oil will be processed in the production plant. This type of method can be applied in scale removal operations for carbonate formations, such as the case of the pre-salt. This is a way to improve the efficiency of reservoir management, through an innovation in the fouling management process.

Example 1: Dynamic Efficiency Tests with Scale Inhibitors

[0024] Dynamic efficiency tests with scale inhibitors were performed with products that present the same active principle based on compounds derived from phosphonic acids with general formula RP(O) (OH).sub.2, with different concentrations of active matter, were carried out at 62° C., using synthetic produced water with the chemical composition of the produced water from well 7-LL-2D-RJS. These results determined the minimum effective concentrations of 10 and 20 mg/L of the inhibitor based on compounds derived from phosphonic acids with the general formula RP(O) (OH).sub.2, with different concentrations of active matter respectively.

Example 2: Flow Tests in Porous Media

[0025] Previous tests of flow in porous media, in which there were used formulations with 10% v/v of the inhibitor based on compounds derived from phosphonic acids with general formula RP(O) (OH).sub.2, diluted in a 2% m/v KCl solution, showed that the inhibitor is adsorbed on the reservoir rock and subsequently desorbed, without causing damage to its permeability. These tests simulated in the laboratory the treatment of scale inhibitor squeeze and allowed to obtain the adsorption isotherms, which can be used for the dimensioning of treatments in producing wells and assessment of the lifetime of these treatments.

Example 3: Flow Test in Porous Media

[0026] In this flow test in porous media, two formulations were used: one 20% v/v formulation of the inhibitor based on compounds derived from phosphonic acids with general formula RP(O) (OH).sub.2, in 15% HCl, and another of the commercial inhibitor as supplied. Tests performed at 60° C. showed that the inhibitor does not negatively impact acidification efficiency. The inhibitor is fixed in the reservoir rock and later released (10), without causing additional damage to its permeability. The inhibitor based on compounds derived from phosphonic acids, with general formula RP(O) (OH).sub.2, was shown to be compatible with: synthetic produced water (calcium content ranging between 2080 and 20000 mg/L), 15% HCl solution and 10% acetic acid solution.

[0027] In this innovation, the scale remover solutions and the scale inhibitor squeeze solutions are mixed and thus form a single solution, which will be injected to simultaneously provide scale removal followed by carbonate rock inhibition of the pre-salt.

[0028] The application and assessment of commercial scale inhibitor based on compounds derived from phosphonic acids with general formula RP(O) (OH).sub.2, diluted in cushions of 75% HCl or 10% acetic acid, is also recommended for testing field and pilot wells, due to the satisfactory results obtained on a laboratory scale with a core sample from the Barra Velha do Campo de Lula reservoir. For a field test, in the pilot well production scenario, the additivation of acid cushions with 20% v/v of the inhibitor based on compounds derived from phosphonic acids with general formula RP(O) (OH).sub.2 is recommended.

[0029] Additionally, it is recommended to apply the same inhibitor at the end of acid cushions, followed by aqueous overflush and another organic one. Thus, it is estimated for this treatment the consumption of 60,000 liters of the inhibitor based on compounds derived from phosphonic acids with the general formula RP(O) (OH).sub.2.

[0030] It is further recommended to carry out an assessment of the compatibility of the inhibitor based on compounds derived from phosphonic acids with the general formula RP(O) (OH).sub.2, with materials, produced fluids and other chemicals dosed in the production system. The efficiency of the recommended treatment should be assessed based on the monitoring of the produced water composition, residual scale inhibitor, production tests and assessment of PDG (downhole pressure gage) and TPI (interval temperature gage) data.

[0031] It should be noted that, although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that it is within the inventive scope defined herein.