RU2182963C1 - Acid composition for treating terrigenous reservoirs - Google Patents

Abstract

FIELD: oil and gas production. SUBSTANCE: composition appropriate, in particular, to intensify inflow of formation fluid by way of acid treatment of terrigenous reservoirs contains ammonium bifluoride or bifluoride-fluoride, sulfamic acid in equimolar proportion, water, and, additionally, 0.5-0.7% of lignosulfates. EFFECT: increased heat resistance of acid composition for treatment of deep-seated terrigenous reservoirs. 2 tbl

Description

 The invention relates to the oil and gas industry, in particular to the intensification of the flow of formation fluid through the acid treatment of terrigenous reservoirs.

 Known acid composition for processing terrigenous reservoirs containing sulfamic acid and ammonium bifluoride [1].

The disadvantage of this composition is that at temperatures above 50 ^o C due to the hydrolysis of sulfamic acid, synthesis of sulfates occurs, forming sediments, clogging the formation.

 The closest in technical essence and the achieved result is an acid composition for processing terrigenous reservoirs, containing, by weight. %: ammonium fluoride 0.56-18.50 or ammonium bifluoride 0.43-14.25, ammonium bifluoride fluoride 0.1-17.00 and water, as well as sulfamic acid in an amount of not more than equimolecular [2].

However, the heat resistance of the known composition is up to 85 ^o C, which limits the possibility of its use for processing deep-seated terrigenous reservoirs.

 The aim of the present invention is to increase the heat resistance of the acid composition for processing deep-seated terrigenous reservoirs.

 This goal is achieved in that the known acid composition for treating terrigenous reservoirs containing ammonium bifluoride or ammonium bifluoride-fluoride, as well as sulfamic acid in an equimolecular amount and the rest of the water, according to the invention additionally contains lignosulfonates in an amount of 0.5-0.7 wt. %

 Lignosulfonates are ammonium or sodium salts of lignosulfonic acids mixed with reducing substances (sugars). Lignosulfonates are low-hazard substances and do not produce irritating and allergic effects.

 The amount of ammonium bifluorides and ammonium bifluoride-fluoride is determined by the mineralogical composition of terrigenous reservoirs in each case separately [1].

 The study of the effectiveness of the proposed composition on artificial core material was evaluated by the recovery coefficient of core permeability. For the experiments, cores (model of the terrigenous layer) were formed, containing, for example, 93 wt.% Quartz seam, 5 wt.% Bentonite clay and 2 wt.% Carbonates.

 For the experiments, the following acid compositions were prepared.

 Composition 1 (prototype): 5.1 wt.% Ammonium bifluoride-fluoride, 9.7 wt.% Sulfamic acid and the rest is water.

 Compositions 2, 3, 4, 5, 6: in composition 1, lignosulfonates were additionally introduced in an amount of 0.2; 0.4; 0.5; 0.7; 0.8 wt.%, Respectively, while the calculated amounts of lignosulfonates and sulfamic acid were simultaneously introduced into the mixing water, after mixing and holding for 30-40 minutes, the calculated amount of ammonium bifluoride was introduced.

 As condensed lignosulfonates, a dry condensed sulphite-alcohol vinasse distillery distillate (KSSB-P) was used, manufactured according to TU 17.06.325-97.

 This order of introducing the components of the composition contributes to the chemical interaction of sulfamic acid and lignosulfonates with the formation of heat-resistant compounds, which provide increased thermal stability of the entire system.

 The permeability recovery coefficient was determined using the UIPK-1M installation according to the procedure in accordance with RD 39-01470099-510-85.

 1. Saturate a core sample with a 3% solution of calcium chloride.

2. Create a hydraulic crimping of the core (200-250 kg / cm ² ).

3. Filter through a core sample of transformer oil (GOST 982-80) with a constant volume velocity Q = 0.05 cm ³ / s.

где Q - объемная скорость фильтрации, м³/с.4. After stabilization of the filtration (30 min), the initial oil permeability of the core sample (K ₀ ) is determined by the formula

where Q is the volumetric filtration rate, m ³ / s.

μ - viscosity of the transformer oil at ³⁰ ° C (μ = 13,1 SP);
l and F, respectively, the length (cm) and cross-sectional area (cm ² ) of the core;
P ₀ is the pressure at the entrance to the core sample before it is treated with an acid composition, kg / cm ² .

 5. Saturate the core images with the acid composition and maintain it in the core for a predetermined time (6 hours).

 6. Displace the acid composition with transformer oil.

где P₁ - давление на входе в образец керна после кислотной обработки, кг/см².7. After stabilizing the filtration, the oil permeability of core K _{1 is} determined by the formula

where P ₁ is the pressure at the entrance to the core sample after acid treatment, kg / cm ² .

В соответствии с отраслевой инструкцией РД 39-0147009-510-85.The impact of the acid composition on the core material was estimated by the coefficient of permeability recovery:

In accordance with industry instructions RD 39-0147009-510-85.

The experiments were carried out at a temperature of 80, 100 and 110 ^o C.

Studies have shown that the introduction of lignosulfonates in an amount of 0.5-0.7 wt.% In the composition ensures its effective use at temperatures up to 100 ^about C (table 1).

From the results of experiments to determine the recovery coefficient shown in table 1, it is seen that when the temperature of the experiments is increased to 100 ^o With this indicator in compositions not containing lignosulfonates or containing them in an amount of less than 0.5 wt.%, Decreases by 15-20 % (compositions 1, 2, 3), while the compositions, which include lignosulfonates and the amount of 0.5-0.7 wt. % (compounds 4 and 5), this indicator increases by an average of 10%. An increase in the content of lignosulfonates (composition 6) practically does not affect the result. Thus, the proposed amount of 0.5-0.7 wt.% Introduced lignosulfonate is optimal.

Experiments at 110 ^o C showed that at this temperature the permeability recovery coefficient deteriorates in compositions containing lignosulfonates, and therefore recommendations for the use of the proposed composition are limited to 100 ^o C.

Thus, the results of laboratory studies indicate the correctness of the selected solution and allow us to recommend the developed acid composition for processing terrigenous reservoirs at temperatures up to 100 ^o C.

 Investigations of the corrosion activity of the acid composition containing lignosulfonates were carried out according to the standard OST 39-099-78 method on St 3 sheet steel sheets measuring 35 • 12 • 3 mm and showed that the weight loss of the samples was negligible (table 2). Introduction to the acid composition of lignosulfonates in an amount of 0.5-0.7 wt.% Helps to reduce corrosion activity by 10-15%.

The proposed technical solution will allow for the acid treatment of deep-lying terrigenous reservoirs with a temperature of up to 100 ^o C.

 The proposed acid composition is not corrosive.

Sources of information
1. UZ Razhetdinov et al. Application of ammonium bifluoride-fluoride for well treatment. The journal "Oil industry", 4, 1984, p. 19-21.

 2. RF patent 2101482, cl. E 21 N 43/27, publ. 1988, BI 1.0

Claims (1)

 An acid composition for treating terrigenous reservoirs containing ammonium bifluoride or ammonium bifluoride-fluoride, as well as sulfamic acid in an equimolecular ratio and the rest of the water, characterized in that it additionally contains lignosulfonates in an amount of 0.5-0.7 wt. %

Images