RU2291181C1 - COMPOSITION FOR PREPARING SOLID PHASE-FREE PROCESS FLUIDS (DENSITY UP TO 1600 kg/m3) DESIGNED FOR COMPLETING AND REPAIRING OIL AND GAS WELLS - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: area of invention is completion and reparation of oil and gas wells and invention can more particularly be used under abnormally high formation pressure and high temperature conditions to drill out salt-bearing deposits, to perform primary and secondary exposing of productive formations, to kill wells and to perform a variety of operations during reparation of wells, including situations wherein hydrogen sulfide is present in formation fluid. Composition according to invention contains. wt %: calcium chloride 31-69, calcium nitrate 28-67, bivalent metal oxide or acetate 0.5-1.2, amine-type corrosion inhibitor 0.75-2.5, and optionally filtration reducer.

EFFECT: extended fluid application area.

2 cl, 1 tbl, 6 ex

Description

The invention relates to the completion and repair of oil and gas wells and can be used under conditions of abnormally high reservoir pressures and high temperatures for drilling saline deposits, primary and secondary opening of reservoirs, for killing wells and performing various types of work during their repair, including in the presence of hydrogen sulfide in the reservoir fluid.

A known composition for the preparation of high-density process fluids, including calcium bromide, in which, in order to reduce the corrosion activity and increase the heat resistance of process fluids and to expand the scope of their application, additionally contains calcium hydroxide and free ammonia (AS USSR 1189868, C 09 K 7 / 04.03.03.84). The main disadvantages of this composition are the high cost and a significant increase in the corrosion activity of the prepared process fluid at a temperature above 100 ° C with a decrease in its density below 1.70 g / cm.

The closest in essence to the claimed is a composition for the preparation of a process fluid without a solid phase for completing and repairing oil and gas wells, containing calcium nitrate, including an organic reagent - a filtering agent based on hydroxyethyl cellulose and a corrosion inhibitor (AS USSR 1684308, C 09K 7/04 09/13/89).

The disadvantages of this composition and liquids based on it are increased corrosion activity and violation of stability and other technological properties at temperatures above 100 ° C and the action of hydrogen sulfide. The density of the liquid does not exceed 1.53 g / cm ³ , and therefore, with possible dilution in contact with formation water, it cannot be restored to its original value. When interacting with hydrogen sulfide, the corrosivity of such a liquid increases sharply, and the resulting solid phase significantly reduces the reservoir properties of the productive formations. In addition, with an increasing share of transportation costs in the cost estimate, transportation of liquid products is economically disadvantageous. The above disadvantages significantly narrow the scope of the composition and process fluids based on it.

The objective of the invention is to expand the scope of the composition for the preparation of process fluids without a solid phase by increasing its density, including in fields containing hydrogen sulfide in their products.

This object is achieved in that the composition for the preparation of process fluids without a solid phase for completing and repairing oil and gas wells contains calcium nitrate and an amine type corrosion inhibitor. New in the composition is that it additionally contains calcium chloride and oxide or acetate of a divalent metal in the following ratios of components, wt.%:

Calcium chloride 31-69 Calcium nitrate 28-67 Divalent Metal Oxide or Acetate 0.5-1.2 Corrosion inhibitor 0.75-2.5

The composition may further comprise a filtration reducer in an amount of not more than 1.2 wt.%.

As an amine type corrosion inhibitor, hexamethylenetetramine and ethylenediamine can be used.

As the bivalent metal oxide or acetate, for example, magnesium or zinc oxide or acetate can be used.

As a filter reducing agent, for example, based on cellulose esters, polyanionic cellulose, hydroxyethyl cellulose can be used.

Obtaining process fluids with a density of up to 1600 kg / m ^{3 is} achieved by simultaneously dissolving a mixture of calcium chloride and calcium nitrate in water and is explained by the synergistic effect, since an aqueous solution of calcium nitrate saturated at 25 ° C has a maximum density of 1.55 g / cm ³ , calcium chloride - 1.41 g / cm ³ .

Since the corrosive activity of aqueous solutions of mixtures of technical chloride and calcium nitrate is high, especially at temperatures above 90 ° C, in order to enhance the protective effect of the corrosion inhibitor by inactivating the present corrosive impurities and stabilizing the properties of the resulting process fluids, the composition additionally includes oxide or divalent metal acetate.

The process of preparing the inventive composition is made by mixing the components. Preparation of process fluids is carried out by dissolving the dry salt composition of the resulting composition in fresh or mineralized water.

For comparison with the claimed composition, a known liquid without a solid phase was prepared.

1. 360 g of calcium nitrate, 5.65 g of hydroxyethyl cellulose and 1.40 g of corrosion inhibitor IKB-4H were dissolved in 200 ml of fresh water. The resulting 365 ml of brine with a density of 1.55 g / cm ^{3 was} tested for corrosion activity and absorption capacity for hydrogen sulfide in accordance with the applicable methods. The filtration rate was measured after thermostating the samples at 130 ° C for 72 hours.

Examples of the preparation of process liquids without a solid phase based on a dry salt composition.

2. 690 g (69 wt.%) Calcium chloride, 280 g (28 wt.%) Calcium nitrate, 5 g (0.5 wt.%) Magnesium oxide and 25 g (2.5 wt.%) Were mixed in a mechanical stirrer. ) a corrosion inhibitor, for example ethylenediamine. The resulting composition was dissolved in 500 ml of fresh water. The resulting 930 ml of brine with a density of 1.59 g / cm ^{3 was} tested analogously to example 1.

3. 690 g (69 wt.%) Calcium chloride, 280 g (28 wt.%) Calcium nitrate, 5 g (0.5 wt.%) Zinc oxide and 25 g (2.5 wt.%) Were mixed in a mechanical mixer. ) a corrosion inhibitor, for example hexamethylenetetramine. The resulting composition was dissolved in 500 ml of fresh water. The resulting 930 ml of brine with a density of 1.59 g / cm ^{3 was} tested analogously to example 1.

4. 310 g (31 wt.%) Calcium chloride, 670 g (67 wt.%) Calcium nitrate, 12 g (1.2 wt.%) Magnesium acetate and 8 g (0.8 wt.%) Were mixed in a mechanical stirrer. ) hexamethylenetetramine corrosion inhibitor. The resulting composition was dissolved in 500 ml of fresh water. The resulting 930 ml of brine with a density of 1.59 g / cm ^{3 was} tested analogously to example 1.

5. 490 g (49 wt.%) Calcium chloride, 490 g (49 wt.%) Calcium nitrate, 7.5 g (0.75 wt.%) Zinc acetate, 7.5 g (0, 75 wt.%) Hexamethylenetetramine corrosion inhibitor and 5 g (0.5 wt.%) Of a filtration reducing agent, for example polyanionic cellulose. The resulting composition was dissolved in 500 ml of fresh water. The resulting 930 ml of brine with a density of 1.59 g / cm ^{3 was} tested analogously to example 1.

6. 490 g (49 wt.%) Calcium chloride, 490 g (49 wt.%) Calcium nitrate, 9 g (0.9 wt.%) Zinc oxide, 6 g (0.6 wt.%) Were mixed in a mechanical stirrer. ) hexamethylenetetramine corrosion inhibitor and 5 g (0.5 wt.%) hydroxyethyl cellulose. The resulting composition was dissolved in 445 ml of fresh water, in which 55 ml of diethanolamine (a hydrogen sulfide neutralizer) was dissolved. The resulting 930 ml of brine with a density of 1.59 g / cm ^{3 was} tested analogously to example 1.

The test results are shown in the table.

The composition of the process fluid Process Fluid Properties Density, g / cm ³ Conditional viscosity T, sec The corrosion rate of steel "D" at 130 ° C, mm / year Indicator filtration, cm ^3/30 min Absorption capacity for hydrogen sulfide, g / l The amount of solid phase, after passing hydrogen sulfide, mg / l one 1.55 40 4,250 35 ? 3200 2 1,59 fifty 0,065 26 0.5 84 3 1,59 fifty 0,045 23 1.7 75 four 1,59 fifty 0.005 23 2,3 37 5 1,59 500 0.003 3 2.1 45 6 1,59 480 0.003 3 6 -

From the tabular data it is seen that the introduction of a divalent metal oxide or acetate into the composition of the dry salt composition of calcium chloride and nitrate along with an amine type corrosion inhibitor and a filter reducing agent, for example, based on cellulose esters, significantly expands the field of application of process liquids prepared on its basis without solid phase. In particular, the corrosive activity of liquids is sharply reduced, and the rate of filtration of thermostated solutions is reduced. In contrast to the prototype, process fluids based on the inventive salt composition practically do not form a solid phase upon contact with hydrogen sulfide, which eliminates the formation of fouling and complications during installation and repair of downhole equipment. Additional processing of liquids can increase their absorption capacity for hydrogen sulfide to 6 g / l without the formation of a solid phase.

Claims (2)

1. The composition for the preparation of process fluids without a solid phase for killing and repairing wells, containing calcium nitrate and an amine type corrosion inhibitor, characterized in that it additionally contains calcium chloride and a bivalent metal oxide or acetate in the following ratio, wt.%: Calcium chloride 31-69 Calcium nitrate 28-67 Divalent Metal Oxide or Acetate 0.5-1.2 Amine Type Corrosion Inhibitor 0.75-2.5 2. The composition according to claim 1, characterized in that it further comprises a filtration reducer in an amount of not more than 1.2 wt.%.