RU2455334C2 - Flush fluid - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: water-base flush fluid consists of, wt %: hydroxylamine chloride 25-30, hydrochinone 0.5 - 1.5, water is the rest.

EFFECT: improvement of spacer fluid flushing ability and, as a result, improvement of cement stone binding with rocks and casing.

1 tbl

Description

The invention relates to the field of drilling wells for underground gas storage (UGS), and in particular to buffer fluids for removing clay cake from the walls of the well before attaching it.

The closest analogue of the claimed invention is a water-based buffer liquid containing mineral salt (aluminum sulfate) and an additive (V.I. Tokunov, A.Z. Saushin. Process fluids and compositions to increase the productivity of oil and gas wells. - M .: Nedra, 2004, p. 455).

The disadvantage of the above buffer fluid is its low washing capacity of clay peel, which does not provide reliable adhesion of cement stone to the casing string and the borehole wall.

The problem to which the claimed invention is directed, is to develop a buffer fluid without the aforementioned disadvantage.

The technical result of the claimed invention is to increase the flushing ability of the buffer fluid and, consequently, to improve the adhesion of cement stone to rocks and casing.

The technical result is achieved in that the water-based buffer liquid contains mineral salt and an additive. In this case, hydroxylamine hydrochloride is used as a mineral salt, and hydroquinone as an additive, in the following ratio of components, wt.%:

hydroxylamine hydrochloride 25-30 hydroquinone 0.5-1.5 water rest

The invention is illustrated in the table, which shows the values of the rate of removal of clay peel by means of a buffer liquid, which is the closest analogue of the claimed invention, and by means of the declared buffer liquid.

The process of preparing the declared buffer fluid is as follows.

A buffer liquid is obtained by preparing an aqueous solution of hydroxylamine hydrochloric acid and introducing an additive - hydroquinone into this aqueous solution. The resulting mixture is mechanically mixed until the reagents are dissolved in water.

Hydroxylamine hydrochloride (hydroxylamine hydrochloride) is a colorless crystal in the form of needles with a density of 1670 kg / m ³ at 17 ° C. The reagent is highly soluble in water (45% at 17 ° C; 66% at 100 ° C). The chemical formula is NH ₂ OH · HCl.

Hydroquinone (paradoxibenzene) is a colorless, often light gray or light brown crystals, density 1358 kg / m ³ . Solubility in water 5.9 g / 100 ml. The chemical formula is C ₆ H ₆ O ₂ . Hydroquinone is obtained by the reduction of benzoquinone formed during the oxidation of aniline.

When developing the claimed composition of the buffer fluid, it was assumed that the buffer fluid should have increased flushing ability.

Depending on the speed of pumping and the volume of buffer fluid during cementing of UGS wells, the interaction time of the buffer fluid with clay cake can be different, but usually does not exceed 10 minutes.

Comparative laboratory studies to study the change in the mass of clay peel from the physico-chemical effects of the claimed buffer fluid and prototype was also carried out for 10 minutes as follows.

To the standard device “Reotest-2M”, a rod was made on which a disk made of fluoroplastic material was screwed.

The clay peel was applied to the disk as follows: a pre-prepared clay paste, which is a mixture of bentonite clay powder and water, was applied with a spatula to the disk. When applying clay paste, its chemical interaction with the test buffer fluid was avoided.

Next, a clay peel disk was placed in a chemical vessel with the test buffer fluid. The tests were carried out in four stages of 2.5 minutes. At a constant speed of rotation, every 2.5 minutes, the clay-peel disk was stopped, removed from the vessel and weighed. The clay-peel disk mass was 17.5 g, and the disk weight without clay-peel was 9 g.

The effectiveness of the impact of the buffer fluid on the clay crust was evaluated by the following formula:

,

,

- скорость удаления глинистой корки;Where

- clay peel removal rate;

n is the number of tests;

m ₀ - the initial mass of clay peel, g;

Δm _i - change in the mass of the clay crust between weighings, g;

t _i is the exposure time of the buffer fluid to the crust in each test at a given speed of rotation of the disk with the crust, min;

i - serial number of weighing.

определяется как доля массы глинистой корки, удаленная за одну минуту ее взаимодействия с буферной жидкостью.Value

is defined as the fraction of the mass of clay peel removed in one minute of its interaction with the buffer fluid.

For example, when using a 25% aqueous solution of hydroxylamine hydrochloride with the addition of 0.5% hydroquinone as a buffer liquid, the removal rate of clay peel will be:

Проведенные исследования показали, что при использовании заявленной буферной жидкости скорость удаления глинистой корки, нанесенной на диск, в 2,5-3 раза выше, чем при использовании известной буферной жидкости. Заявленная буферная жидкость оказывает более существенное физико-химическое воздействие на глинистую корку по сравнению с прототипом.

Studies have shown that when using the declared buffer fluid, the removal rate of clay peel deposited on the disk is 2.5-3 times higher than when using the known buffer fluid. The claimed buffer fluid has a more significant physico-chemical effect on the clay crust compared with the prototype.

The use of the declared buffer fluid will allow for more reliable contact of cement stone with the wall of the well and the surface of the casing, which will increase the reliability and durability of the fastening of UGS wells.

Table The composition of the buffer fluid, wt.% The mass of the disk with clay crust, g Test time t, min Clay mass loss, g

Peeling rate,

Known Buffer Fluid Aluminum sulfate - 10%; Water - 90%. 17.50 0 0 0.024 16.88 2.5 0.44 16.21 5,0 0.49 15.50 7.5 0.55 14.73 10 0.59 Suggested Buffer Fluid Hydroxylamine hydrochloride - 25%; Hydroquinone - 0.5%;
Water - 74.5%. 17.50 0 0 0,069 16.11 2.5 1.39 14.65 5,0 1.46 13.11 7.5 1,54 11.59 10 1,52 Hydroxylamine hydrochloride - 30%; Hydroquinone - 1.5%;
Water - 68.5%. 17.50 0 0 0,073 16.02 2.5 1.48 14.48 5,0 1,54 12.90 7.5 1,58 11.27 10 1,63

Claims (1)

A water-based buffer liquid containing mineral salt and an additive, characterized in that hydrochloric acid hydrochloramine is used as a mineral salt, and hydroquinone is used as an additive in the following ratio, wt.%:
hydroxylamine hydrochloride 25-30 hydroquinone 0.5-1.5 water rest