RU2458958C1 - Method of treating water-based process liquids used in drilling and well workover - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: in the method of treating water-based process liquids used in drilling and well workover, by adding a sodium halide-based clay inhibitor, the clay inhibitor is a furacilin preparation containing furacilin and sodium chloride in amount of 0.8-4.2 wt %.

EFFECT: high efficiency of the treatment method owing to improved inhibiting properties, wide range of clay inhibitors.

11 ex, 2 tbl

Description

The invention relates to the oil and gas industry, namely, to the processing of technological fluids, water-based, used in drilling and workover.

Analysis of the current level of technology showed the following:

- there is a method of treating drilling fluid used in drilling with sodium chloride in order to suppress the swelling of unstable clay rocks (see Gorodnov VD Physico-chemical methods for preventing complications in drilling. M: Nedra, 1984. p. 33-35) .

The disadvantage of this method of processing washing liquid is as follows.

The inhibitory effect of sodium chloride is manifested when it is introduced into the composition of the solution in an amount of at least 5 wt.%, With an increase in concentration (up to 20 wt.%), The inhibition efficiency increases, but the cost of the well drilling work increases due to the high reagent consumption . In addition, solutions with a high content of sodium chloride require additional treatment with salt-resistant reagents, which leads to an increase in the cost of the work. Processing the wash liquid with a large amount of sodium chloride leads to its liquefaction, which, in turn, requires the additional introduction of thickening additives, and also increases the cost of drilling operations;

- as a prototype, a method of chemical treatment of drilling fluids by introducing a clay inhibitor, in which sodium and / or potassium silicofluorides in the amount of 0.5-3.0 wt.% (AS USSR No. 1199786 from 04/07/1983 according to class S09K 7/02, published on 12/23/1985, BI No. 47).

The disadvantage of this method of processing a drilling fluid is the following. It is known that the greatest contribution to the inhibition of swelling of clay minerals is made by the cations of compounds that can displace the cations present in the native clay mineral, thereby inhibiting its swelling.

When drilling fluids are treated with sodium silicofluoride, the latter inhibits clay minerals due to the presence of sodium ions in its composition. Moreover, it is a poorly soluble compound in water, the concentration of sodium ions is kept at a low level, therefore, the effectiveness of inhibition of clay minerals will be low. The relatively high values of the degree of swelling, compared with sodium silicofluoride, obtained by treating the drilling fluid with potassium fluorosulfide, are explained by the higher inhibitory effect of potassium ions, which are formed upon dissociation of this compound. However, in this case, due to the low solubility of potassium silicofluoride, the concentration of potassium ions is kept low, therefore, the drilling fluid will have insufficient inhibitory properties, therefore, the effectiveness of the inhibition of clay minerals by such a solution will be low. Improving the inhibitory properties of the solution to a greater extent does not occur due to the introduction of sodium and / or potassium silicofluorides, but rather due to the presence of ingredients such as HPAA, CMC, KSSB, USR, magnesium chloride and sodium, oil that have a high inhibitory concentration, included in the drilling fluid formulation action.

This is confirmed by a comparison of the data on the inhibition of clay minerals reproduced by the authors of the present invention (see test report, table 1). In addition, sodium and potassium silicofluorides are toxic substances with a general toxic and irritating effect. The hazard class of these substances is II (hazardous substances).

The technical result that can be obtained by implementing the present invention is: increasing the efficiency of the processing method by increasing the inhibitory properties of water-based process fluids used in drilling and workover, expanding the range of clay inhibitors.

The technical result is achieved using a known method of processing water-based process fluids used in drilling and workover, by introducing a clay halide inhibitor based on sodium halide. In which furatsilin containing furatsilin and sodium chloride, is introduced in the amount of 0.8-4.2 wt.% As the indicated clay inhibitor.

The inventive method meets the condition of "novelty."

Use the drug furacilin of the following composition, parts by weight:

Furatsilin one Sodium chloride 40,

(Pharmacopoeia article FS 42-2611-96. Pharmacopoeia State Committee. Ministry of Health and Medical Industry of the Russian Federation, 1996). The indicated drug furatsilin is also described on the Internet at the following sites:

http://www.rlsnet.ru/tn_index_id_5396.htm;

http://www.nsk.vedun.ru/l_med_lecvo_info.php?scrmode=comp&id_lecvo=1992;

http://www.reles.ru/cat/tradefm/Tabulettae%20Furacilini%20ad%20usum%20extemum%20002%20g/5;

http://slovari.yandex.ru/~%D0%BA%D0%BD%D0%B8%D0%B3%D0%B8/%D0%A0%D0%9B%D0%A1/%D0%A4% D1% 83% D1% 80% D0% B0% D1% 86% D0% B8% D0% BB% D0% B8% D0% BD /.

The processes occurring in the system "technological fluid - clay rock" are accompanied by the absorption of water with the release of energy, leading to softening of clay rock (up to 30-50% or more), a decrease in fracture resistance (up to 70%). In addition, if clayey rocks are limited in volume and their volumetric expansion is difficult, then internal swelling stresses develop, reaching values exceeding the fracture resistance.

Clay is a rock with a number of unique properties, the most important of which are the ability to disperse in the aquatic environment and swell in it. When clay minerals swell in water, hydration shells form around exchange cations. The greatest swelling ability in water is possessed by montmorillonite, in which Na ⁺ is the main exchange cation. Clay (bentonite) refers to finely porous sorbents. Its structure has primary and secondary porosity. Primary porosity is due to the crystalline structure of minerals, secondary pores are formed by gaps between contacting particles. During the adsorption of polar substances, the lattice of primary pores expands, and one or more layers of an adsorbate — an inhibitor — penetrate into the interpackage space. The specific surface area of the primary pores reaches 420-470 m ² / g. The preferred radius of the secondary pores is 5-10 nm, their specific surface area does not exceed 60 m ² / g. Depending on the properties of the process fluids, when they come into contact with unstable clay rocks, the latter may swell or disintegrate. Swelling occurs under the influence of a fresh, alkaline or slightly mineralized solution. Clays of the montmorillonite group are most exposed to technological liquids. The swelling that occurs as a result of hydration of the clay material of the formation is the result of adsorption, osmotic and capillary forces that hold water in a structured system. Most of the water retained by the clay particles is in a bound state. If the clay rock is in the form of a suspension in an aqueous solution and water molecules can penetrate between the individual layers of the cells, then the cations of the mineral move freely and can exchange with the cations present in the solution.

In the claimed processing method, a clay halide inhibitor based on sodium halide is used as a clay inhibitor — a furatsilin preparation containing furatsilin and sodium chloride in an amount of 0.8-4.2% of the volume of process liquids.

It is known to use metal salts of groups I and II of the Periodic System — KCl, NaCl, Na ₂ SiO ₃ , CaCl ₂ , MgCl ₂ to prevent the swelling of clay minerals. In this case, effective inhibition of clay minerals occurs when large quantities of these salts are contained in process fluids.

The inhibitory effect of the drug furatsilin is due to the mutual influence of its components: furatsilina - (2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide) and sodium chloride. The presence of furatsilin 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide in the preparation increases the inhibitory properties of the process fluids that it processes. Based on the performed laboratory studies, the authors found that the clay swelling inhibitor proposed for processing in the claimed amount is a synergistic mixture of two ingredients, which allowed the authors to establish an increase in the inhibitory ability of the process fluids he processes. The decrease in clay swelling in the solution of the drug furatsilin is due to the emergence of new character-specific bonds. The formation of the latter is as follows. On the surface of the clay mineral particles, there are hydrophilic and hydrophobic adsorption centers on which selective sorption of both undissociated 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide molecules and ions to which sodium chloride dissociates can occur. It can be sorbed by hydrophobic groups on the hydrophobic centers of the adsorbent, and by hydrophilic groups on the hydrophilic centers of the adsorbent. If these areas belong to different particles of the mineral, then along with the processes of changing the physicochemical properties of minerals, processes occur associated with the formation of additional structural bonds and hardening of the ground mass as a whole, which is reflected in a decrease in the ability of a stabilized mineral to swell in water.

2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide can act both as a cation and anion due to the presence of a nitro group in the molecule:

Due to the presence of a positive charge on the nitrogen atom, 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide can act as an exchange ion, displacing inorganic cations from the interplanar space of a clay mineral. When water-based process fluids are used in the drilling and overhaul of wells treated with furatsilin, clay surface modification occurs, which manifests itself in a change in the chemical nature of the external and internal silicon-oxygen surface of the particles, displacement of interlayer water and the exchange of alkali and alkaline earth metal cations for molecule 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide.

As a result of these processes, the effective amount of adsorption space decreases, which is expressed in a sharp decrease in the swelling ability of the mineral. Molecules 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide affect the secondary porosity of clays, which is due to the following. The molecule 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide contains -NH-acid centers due to the electron-withdrawing ability of the nitro group and carbonyl oxygen, and proton can be replaced by Fe ²⁺ and Fe ³⁺ cations that act in as Lewis acids, and the formation of coordination compounds with nitrogen atoms as ligands. The indicated coordination compounds of metals with 2 - [(5-nitro-2-furanyl) methylene] hydrazinecarboxamide are water-insoluble substances that will prevent the penetration of water molecules into the interlayer space of clay rock.

The introduction of the drug furatsilin containing furatsilin and sodium chloride in technological fluids in an amount of less than 0.8 wt.% Of their volume leads to an increase in the degree of swelling of clays.

The introduction of the drug furatsilin containing furatsilin and sodium chloride in technological liquids in an amount of more than 4.2 wt.% Is impractical, since it does not lead to complete dissolution of the drug furatsilin, leads to overuse of the reagent.

Thus, according to the foregoing, the achievement of the claimed technical result is ensured.

The inventive method meets the condition of "inventive step".

In more detail, the essence of the claimed invention is described by the following examples.

Examples (laboratory).

Table 1 shows these values of the degree of clay swelling after contact with water (example No. 1) and an aqueous solution of furatsilin containing furatsilin and sodium chloride, with various clay samples.

Table 2. Examples No. 1, 2 - properties of process fluids without treatment by the proposed method.

Example No. 3. The process fluid used in the overhaul of the wells is treated, containing SEANEC TU 5 g (0.5 wt.%) And 987 ml (98.7 wt.%) Water, by introducing 8 g (0.8 wt.%) Of the drug furatsilin containing furatsilin and sodium chloride. Mixed. The properties of the solution are determined: pH = 7.5, nominal viscosity T = 45 s, plastic viscosity η = 12 mPa · s, dynamic shear stress DNS = 67 dPa, static shear stress in 1/10 min SNS = 19/19 dPa, water loss F = 5.5 cm ^3/30 min, the nonlinearity coefficient n = 0,4, the degree of swelling clay sample - 2.1.

Example No. 4. Process the process fluid used in the overhaul of wells containing SEANEC TU 5 g (0.5 wt.%) And 953 ml (95.3 wt.%) Of water by introducing 42 g (4.2 wt.%) Of the drug furatsilin, containing furatsilin and sodium chloride. Mixed. Determine the solution properties: pH = 7,5, T = 28, η = 14 mPa · s, CSN = 69 dPa, SNA = 19/19 dPa, F = 5.5 cm ^3/30 min, n = 0,45 , the degree of swelling of the clay sample is 1.2.

Example No. 5. The process fluid used in the overhaul of the wells is treated, containing SEANEC TU 5 g (0.5 wt.%) And 970 ml (97 wt.%) Water by introducing 25 g (2.5 wt.%) Of furatsilin containing furatsilin and sodium chloride. Mixed. Determine the solution properties: pH = 7,5, with T = 50.0, η = 10 mPa · s, CSN = 58 dPa, SNA = 16/16 dPa, F = 5.3 cm ^3/30 min, n = 0 , 4 the degree of swelling of the clay sample is 1.6.

Example No. 9. Process the process fluid used in drilling wells containing 81 g (8.1 wt.%) Bentonite, KSSB-2M 150 g (15 wt.%) And 761 ml (76.1 wt.%) Water by introducing 8 g ( 0.8 wt.%) Of the drug furatsilin containing furatsilin and sodium chloride. Mixed. Determine the solution properties: pH = 8,2, T = 38, η = 16 mPa · s, CSN = 40 dPa, SNA = 48.2 / 55.2 dPa, F = 5.5 cm ^3/30 min, the degree of clay sample swelling - 1.9.

Example No. 10. Process the liquid used in drilling wells containing 81 g (8.1 wt.%) Bentonite, KSSB-2M 150 g (15 wt.%) And 761 ml (76.1 wt.%) Water by introducing 8 g (0 , 8 wt.%) Of the drug furatsilin containing furatsilin and sodium chloride. Mixed. Determine the solution properties: pH = 8,2, T = 38, η = 16 mPa · s, CSN = 40 dPa, SNA = 48.2 / 55.2 dPa, F = 5.5 cm ^3/30 min, the degree of clay sample swelling - 1.6.

Example No. 11. Process the process fluid used in drilling wells containing 81 g (8.1 wt.%) Bentonite, KSSB-2M 150 g (15 wt.%) And 727 ml (72.7 wt.%) Water by introducing 42 g ( 4.2 wt.%) Of the drug furatsilin containing furatsilin and sodium chloride. Mixed. Determine the solution properties: pH = 8,2, T = 36, η = 18 mPa · s, CSN = 42 dPa, SNA = 50/56 dPa, F = 5.4 cm ^3/30 min, degree of swelling clay sample - 1,2.

Thus, the claimed technical solution meets the conditions of "novelty, inventive step and industrial applicability", that is, is patentable.

Table 1 ACT laboratory test No. p / p The inhibitor content in the solution, wt.% Contact time with solution, h Clay rock swelling rate bentonite clay clay well 934 North Stavropol field interval 740-745.6 clay well 7962 Sandy interval 3144.8-3159.0 (chokrak) one 2 3 four 5 6 one 0 24 6.0 3.6 2.6 2 0.8 24 4.0 2.0 2.1 3 2.5 24 2.9 1,5 1,6 four 4.2 24 1.8 1.3 1,2 5 0.7 24 4.8 2.2 2.2 6 4.3 24 1.7 1,2 1,1 Analogue Sodium chloride 2.5 wt.% 24 4.2 2.1 2,3 Prototype 7 Sodium cremnefluoride 1 wt.% 24 5.3 2.5 1.9

table 2 No. p / p Component composition, wt.% Process Fluid Properties pH conditional viscosity T, s plastic
viscosity η, MPa · s dynamic stress
shear rate τ ₀ , dPa static
something tense
shear in 1/10 min, dPa water drain
ca F, ^cm3 / 30 min coefficient
ent nonlinearity, n the degree of swelling of the bentonite clay sample one 2 3 four 5 6 7 8 9 10 one SEANEC TU - 0.5 7.5 56.8 7 52.7 14/14 5.8 0.4 4.0 Water - 99.5 2 SEANEC TU - 0.5 8 26.0 12 67 19/19 5,6 0.54 3,5 Sodium Chloride - 0.5 Water - 99.0 3 SEANEC TU - 0.5 7.5 45 12 67 19/19 5.5 0.4 2.1 The drug furatsilin - 0.8 Water - 98.7 four SEANEC TU - 0.5 7.5 28 fourteen 69 19/19 5.5 0.45 1,2 The drug furatsilin - 4,2 Water - 95.3 5 SEANEC TU - 0.5 7.5 fifty 10 58 16/16 5.3 0.4 1,6 The drug furatsilin - 2.5 Water - 97.0 6 SEANEC TU - 0.5 7.5 56.8 7 52.7 14/14 5.8 0.4 3,5 The drug furatsilin - 0.7 Water - 98.8 7 SEANEC TU - 0.5 7.5 28 fourteen 69 19/19 5.5 0.45 1.18 The drug furatsilin - 4.3 Water - 95.2

Continuation of table 2 one 2 3 four 5 6 7 8 9 10 8 Bentonite - 8.1 8.2 40 fifteen 38 32.8 / 44.3 6.5 - 3.8 KSSB-5 - 15 Water - 76.9 9 Bentonite - 8.1 8.2 38 16 40 48.2 / 55.2 5.5 - 1.9 KSSB-2M - 15 The drug furatsilin - 0.8 Water - 76.1 10 Bentonite - 8.1 8.2 38 16 40 48.2 / 55.2 5.5 - 1,6 KSSB-2M - 15 The drug furatsilin - 2.5 Water - 74.4 eleven Bentonite - 8.1 8.2 36 eighteen 42 50/56 5,4 - 1,2 KSSB-2M - 15 The drug furatsilin - 4,2 Water - 72.7 12 Bentonite - 8.1 8.2 38 16 40 48.2 / 55 5.5 - 3.0 KSSB-2M - 15 The drug furatsilin - 0.7 Water - 76.2 13 Bentonite - 8.1 8.2 36 eighteen 42 52/54 5,4 - 1,2 KSSB-2M - 15 The drug furatsilin - 4.3 Water - 72.6 Note:
* - hydromica monmorilonite with a content of monmorilonite up to 75%.
** - hydromica monmorilonite with a content of monmorilonite up to 7%.

1. The degree of clay swelling is the relative increase in the mass or volume of a clay sample to a specific point in time at a given temperature. The degree of clay swelling is determined on the LGU design device by the difference between the volume of liquid taken for the experiment and the volume of non-absorbed liquid (colloid chemistry workshop: Textbook / Ed. By M.I. Gelfman. - St. Petersburg: publishing house "Lan", 2005 .-- 256 p.).

2. The rheological properties of the solution are determined using a “Fann-35A” reoviscimeter.

3. Water yield is determined on a Baroid filter press at ΔР = 0.1 MPa.

Claims (1)

A method of processing water-based process fluids used in drilling and workover by introducing a clay halide inhibitor based on sodium halide, characterized in that a furatsilin containing furatsilin and sodium chloride is administered as a clay inhibitor in an amount of 0.8-4 , 2 wt.%.