RU2559267C1 - Composition for treatment of bottomhole zone of terrigenous reservoirs - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: composition for treatment of the reservoir bottomhole zone contains the following elements in wt %: oxyethylidenediphosphoric acid 12-15; sodium alpha olefin sulfonate 3-5; water - the remaining part.

EFFECT: improved efficiency for treatment of bottomhole zone of terrigenous reservoirs.

1 tbl

Description

The invention relates to the oil and gas industry, and in particular to compositions for treating the bottom-hole formation zone (PZP), in particular terrigenous reservoirs, and can be used to restore the permeability of the bottom-hole zone of the formation and increase the productivity of production wells in gas fields and underground gas storages (UGS).

A known composition for the acid treatment of the bottomhole zone of a low permeable terrigenous formation (RF patent No. 2388786, C09K 8/78, publ. 05/10/2010), containing, wt.%:

inhibited hydrochloric acid (on HCl) 9.0-15.0 fluorine-containing component - hydrofluoric acid or ammonium bifluoride, or ammonium fluoride (on HF) 4.0-7.4 neonol and / or phosphonic acid 0.1-2.0 organic solvent - oxal T-66 5.0-30.0 water rest.

The disadvantage of this composition is that when processing the PPP of a terrigenous reservoir containing carbonate substances, when using hydrochloric and hydrofluoric acids as a result of reaction with quartz, clay and carbonate rock, poorly soluble and insoluble precipitates of silicic acid gel, fluorides and fluorosilicates are formed, which lead to a significant reduction in permeability of the reservoir.

The closest analogue to the proposed structure (prototype) is a composition for processing the bottomhole formation zone (RF patent No. 2047757, E21B 43/27, publ. 10.11.1995) containing nitrilotrimethylphosphonic acid, dichloride bis- (N, N-dimethyl-N β-carbodeoxymethyl-N-ethyleneammonium) sulfide and water in the following ratio, wt.%:

nitrilotrimethylphosphonic acid dichloride-bis- (N, N-dimethyl-N-carbodecoxymethyl-N-ethyleneammonium) 0.005-0.15 sulfide 0.1-0.5 water Rest

The disadvantage of this composition is the low efficiency of processing the terrigenous reservoir, due to the low concentration of the acid composition and, as a consequence, the weak physicochemical effect of the known composition on clay rocks of terrigenous reservoirs.

The problem to which the invention is directed, is to develop a composition that allows to restore the permeability of the reservoir to a value close to the original, due to the removal of clay mudding formations.

The technical result, the achievement of which the present invention is directed, is to increase the efficiency of cleaning PZP of terrigenous reservoirs by improving the permeability of PZP due to the destruction of coagulation structural bonds between clay formations.

This technical result is achieved due to the fact that the composition for treating the bottom of the formation containing phosphonic acid, a surfactant and water, for treating terrigenous reservoirs as phosphonic acid contains hydroxyethylidene diphosphonic acid, and sodium alpha olefin sulfonate as a surfactant in the following ratio of components, wt.%:

hydroxyethylidene diphosphonic acid 12-15 alpha sodium olefin sulfonate 3-5 water rest

The composition of the drilling fluid used during the opening of the productive horizon greatly affects well productivity. During the drilling process, the pore space of the near-borehole part of the formation is clogged by the solid phase of the drilling fluid, the permeability of the bottomhole zone is reduced due to the formation of a filter cake, penetration of the mud filtrate, as well as dispersion and swelling of the rock skeleton components. To restore the permeability of the reservoir, in practice, acid compositions are used that have various physicochemical properties.

The following components are used to prepare the proposed composition for treating PPP: water, hydroxyethylidene diphosphonic acid and sodium alpha olefin sulfonate. Under laboratory conditions, the acid composition is prepared as follows: the calculated amount of water is poured into the desiccator, the calculated amount of hydroxyethylidene diphosphonic acid, weighed on an analytical balance, is added to it, stirred with a laboratory stirrer until completely dissolved, after which the calculated amount of sodium alpha olefin sulfonate is gradually added and the mixture is mixed in within 5 minutes.

Oxyethylidene diphosphonic acid (OEDPK) - a white powder with a grayish or beige tint, belongs to the class of phosphonic acids with a high complexing ability and resistance to hydrolysis. OEDFK is well dissolved in water, acids, alkalis, methanol and ethanol. It is produced by industry according to TU-2439-363-05763441-2002.

Sodium alpha olefin sulfonate (AOC) is obtained by sulfonation of C ₁₂ -C ₁₄ , C ₁₄ alpha olefins, followed by neutralization, Anionic surfactant is a liquid, transparent to yellowish, with an active substance content of at least 35%. Country of origin - China.

The study of the influence of the known and proposed compositions on the restoration of the permeability of clay samples was carried out on a laboratory setup described in RF patent No. 96962, G01N 1/004, publ. 08/20/2010.

The sequence of the experiment is as follows. After the working sample was formed (the inner part of the mesh cylinder was filled with a sample of quartz sand with a diameter of 0.5-0.6 mm, the peripheral part was 0.1-0.2 mm and the filling was sealed with compression nuts), water was filtered through it from above, the flow rate was measured and determined the initial coefficient of permeability of the sample at a given pressure drop, which was calculated by the formula

where µ is the dynamic viscosity coefficient of the pumped medium, Pa · s;

l, d - length and diameter of the working sample, m;

P is the inlet pressure, Pa;

P _at - atmospheric pressure, Pa;

Q - flow rate, m ³ / s.

At the same pressure drop, a clay solution with a density of 1070 kg / m ^{3 was} filtered through the sample, the flow rate (Q) was determined, and the permeability coefficient (k) of the sample after claying was calculated by formula (1). Then, the test acid composition was pressed into the sample and the liquid was left at rest for 6 hours. After the reaction was completed, water was pumped in the opposite direction and the permeability coefficient of the sample after exposure to the acid composition at a given pressure drop was determined. The scatter of data obtained from repeated experiments did not exceed 10%.

The invention is illustrated in the table, which shows the experimentally obtained values of the permeability coefficients after processing zaklinirovannyh samples known and proposed compositions.

From the results given in the table, it follows that the content of OEDFK in an amount of from 12 ÷ 15 wt.%, And AOS - 3 ÷ 5 wt.% (Paragraphs 3, 5, 6 of the table) is optimal for achieving a technical result.

As can be seen from the table, the use of the proposed composition for the processing of the bottom-hole zone of terrigenous reservoirs will increase the efficiency of processing and increase the productivity of wells by 2-2.5 times in comparison with the known composition.

Claims (1)

Composition for treating the bottom of the formation zone containing phosphonic acid, a surfactant and water, characterized in that the composition for treating the bottom of the formation zone of terrigenous reservoirs contains oxyethylidene diphosphonic acid as phosphonic acid and sodium alpha olefinsulfonate as surfactant when the following ratio of components, wt.%:
hydroxyethylidene diphosphonic acid 12-15 alpha sodium olefin sulfonate 3-5 water rest