RU2705111C1 - Composition for limiting water influx into well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry, in particular, to compositions for isolation of water influx in production wells and treatment of injection wells in order to level acceleration profile and increase coverage of beds by flooding. Composition contains 5–20 wt% of liquid glass with silicate module 2.7–3.5, 0.5–1 wt% over 100 % sodium aluminate and 80–95 wt% of water.

EFFECT: increased efficiency of isolation of water influx into well and manufacturability due to increased strength of composition at controlled time of gel formation at low reservoir temperature and simplified preparation.

1 cl, 1 tbl

Description

The proposal relates to the oil industry, in particular to compositions for isolating water inflow in producing wells and treating injection wells in order to equalize the injectivity profile and increase the coverage of formations by water flooding.

A known composition for limiting water inflow into the well (patent RU No. 2525079, IPC E21B 33/138, publ. 08/10/2014 in bull. No. 22) containing liquid glass, 0.03-0.05% solution of DP9-8177 polyacrylamide and a gelation regulator in the following ratio of components,% vol .:

liquid glass 20-50 0.03-0.05% solution of DP9-8177 polyacrylamide 10-15 gelling regulator 40-65,

as a gelation regulator use a 10-20% solution of calcium chloride technical or 10-20% solution of POLYPACS-30 LF (polyaluminium chloride). Pre-mixed solution of DP9-8177 polyacrylamide and water glass until a homogeneous mixture is obtained. Then the resulting mixture and the gelation regulator are subsequently pumped.

A disadvantage of the known composition is that the compositions are not fully mixed in the isolation zone, as a result of which the gel is not formed in full, which reduces the result of limiting water inflow from the use of the composition.

A known composition for limiting water inflow into the well (patent RU No. 2083816, IPC E21B 43/32, 33/138, publ. 07/10/1997 in bull. No. 19), containing mineralized water of calcium-chloride type and precipitating agent. These components of the composition are separated by light oil, and a 5-7% aqueous solution of sodium aluminate is used as the precipitating agent in the following ratio of components, wt. %:

calcium chloride mineralized water 40 light oil 10 5-7% aqueous solution of sodium aluminate fifty.

A disadvantage of the known composition is that during the interaction of mineralized water of calcium chloride type with sodium aluminate, gelation does not occur, but calcium aluminates and calcium hydroxide are formed, which are poorly soluble in water, and they precipitate as a suspension.

The closest analogue is the composition for restricting water inflow into the well (patent RU No. 2168618, IPC E21B 43/22, publ. 06/10/2001 in bull. No. 16) containing liquid glass, as a gelling agent - ammonium nitrate and fresh water in the following ratio components, wt. %:

liquid glass 20,0-40,0 ammonium nitrate 3.0-7.0 fresh water rest.

The specified composition may additionally contain an anionic surfactant, for example, DS-RAS, sulfonol in an amount of 1-3% by weight of a composition based on sodium silicate.

A disadvantage of the known composition is the impossibility of its gelation at low temperatures. For the hydrolysis of ammonium nitrate (ammonium nitrate), which causes the gelation of liquid glass, a temperature of at least 50 ° C is needed. A significant drawback is also the low strength of the obtained gels, which is proved by the maximum viscosity indicated in the closest analogue - 1600 mPa⋅s.

Technical tasks are to increase the efficiency of isolation of water inflow into the well and manufacturability by increasing the strength of the composition with an adjustable gelation time at low reservoir temperature and simplifying the preparation.

Technical problems are solved by a composition for limiting water inflow into a well containing liquid glass, a gelling agent and water.

New is that liquid glass is used with a silicate module of 2.7-3.5, sodium aluminate is used as a gelling agent in the following ratios of the components of the composition, wt. %:

silicate water glass 2.7-3.5 5-20 sodium aluminate 0.5-1 over 100% fresh water 80-95.

The following reagents are used to prepare the composition:

- liquid glass (sodium silicate) according to GOST 13078-81 - is a thick yellow or gray liquid with a density in the range of 1360-1450 kg / m ³ with a silicate module in the range of 2.7-3.5;

- sodium aluminate (NaAlO ₂ ) according to TU6-09-01-727-87 - is a white soluble white powder with a ratio of the percentage of sodium oxide to aluminum oxide (Na ₂ O: Al ₂ O ₃ ) in the range of 0.86 -1.14. It is known that sodium aluminate is used to accelerate the hardening of concrete;

- fresh water.

The essence of the proposal is to create a composition to limit water flow in low-temperature wells. The composition is easy to prepare, convenient for pumping into the well, has an adjustable gelation time and low cost. Liquid glass with a silicate module of 2.7-3.5 is low-modulus and inexpensive in contrast to high-modulus liquid glass with a silicate module above 3.5. Water glass and sodium aluminate are available reagents that are available in large volumes. They dissolve well and quickly in water. After mixing the components of the composition in the specified range of ratios of the components at room temperature, a gel forms, which in a few hours after the formation acquires a dense structure.

In laboratory conditions, the composition is prepared as follows. At a temperature of 22 ± 2 ° C, a weighed portion of sodium aluminate in an amount of 1 g (in excess of 100 wt.%) Is added to a glass beaker with a volume of 150 ml, 88 g (88 wt.%) Are poured, mixed until dissolved, then in the resulting solution with stirring liquid glass was slowly poured into 12 g (12 wt.%) and the composition was left to gel (experiment 6). After gel formation, its strength (static shear stress) is determined at room temperature using a shirometer in accordance with GOST 33213-2014. The results of gelation and determination of the strength of the composition based on water glass and sodium aluminate are presented in the table. The optimal performance of gelation time and strength provides the proposed composition. The remaining experiments are prepared similarly to experiment 6.

The compositions prepared at exorbitant concentrations of the components have a short gelation time or low strength: the composition according to experiment 1 formed a flowing gel, the strength of which was not measured, and the composition according to experiment 10 has a short gelation time (30 min).

The maximum gel time of the proposed composition is 14 hours, and the maximum gel strength is 304.7 Pa, unlike the composition according to the closest analogue, which has a maximum gel time of 6 hours (experiment 12) and a maximum gel viscosity of 1600 mPa⋅s ( experience 11), that is, the gel is fluid.

According to the test results of the composition for the duration of gelation and strength, presented in the table, a range of component ratios, wt. % .:

silicate water glass 2.7-3.5 5-20 sodium aluminate 0.5-1 over 100% water 80-95.

Thus, the technical tasks have been achieved - the creation of a gel-forming composition with high strength, adjustable gelation time at low temperature and easy to prepare.

Claims (2)

Composition for limiting water inflow into a well containing liquid glass, a gel former and water, characterized in that the composition uses liquid glass with a silicate module of 2.7-3.5, and sodium aluminate is used as a gel former in the following ratios of components, wt. %: liquid glass with silicate module 2.7-3.5 5-20 sodium aluminate 0.5-1 over 100% water 80-95.