SU791943A1 - Method of preventing salt deposition in a well - Google Patents

Description

(54) METHOD FOR PREVENTION OF SALT DEPOSITS IN SKVAYSINE

The invention relates to the field of oil production and mohsset be used to prevent salt deposits in squamous and well equipment.

There is a known method of preventing salt deposits in the well and well equipment by treating water in the wellbore in the bottomhole zone of a squashine with a salt inhibitor

one .

However, with significant content in the mineralized formation water ;: galsie ions from 3000 mg / l and more, difficulties arise when pumping a salt inhibitor; xe 5 into the wellbore zone, since the formation of an intractable calcium salt of the inhibitor. This leads to the inefficiency of the reagent treatment of the well bottom zone. The elimination of this undesirable phenomenon is possible by injecting a formation of an aqueous solution of a salt precipitator in such a formation in such a concentration that the compatibility of the system / s: the aqueous solution of the inhibitor — mineralized formation water is complete, i.e. it is necessary to inject an inhibitor with a lower concentration.

2

There is a known method for preventing saline deposits in a well by treating watered oil in the well bottom zone with an aqueous solution.

S salt inhibitor 12. The amount of scale inhibitor BLJ is chosen to be injected into. the retinue inhibitor was fully compatible with the aHtiUMi mineralization

About reservoir waters.

Where solution compatibility is a problem, the following approach is used: injection is performed with a lower reagent concentration, up to 1 and 2%; dilute the reservoir solution with low calcium ion solutions, if available.

Compatibility to be full

20 otherwise sz.t11, opa:; nost wasp) kden15 peajeHTa in C1 system of pipes (equipment) or in the suite of layers.

Thus, as a prototype, a method for preventing salt deposition in the well during production, collection and transport of flooded oil by treating the bottomhole zone of the well with the Coaxit-7647 scaling inhibitor, 30, has been chosen so that, in order to eliminate

In the event of incompatibility of saline stratal water containing kashti ions with a scaling inhibitor, the treatment is carried out with an aqueous solution of the inhibitor at a concentration until the compatibility of the inhibitor solution and the stratum reservoir is complete.

The known method has a number of residues. Treatment of flooded oil in the wellbore zone of the well with an inhibitor at a concentration of the active substance of 1–2% co-causes a sharp increase in the volume of captured fluid, which inevitably leads to a decrease in the phase permeability of the oil producing formation and an increase in water (undesirable phenomenon from the standpoint of formation physics). The known technical solution inevitably leads to difficulties in the development after treatment of the well bottom-hole zone with an aqueous solution of salt inhibitor. And the last difficulty in the wide use of this technical solution lies in the fact that in areas with a shortage of fresh water (which also includes the Orenburg region) it is not economically feasible to carry out well treatments according to the prototype method. For example, in PGDU Buguruslanneft, a number of wells were processed by a known method. The treatments were carried out according to the method proposed by ESSO Chemicals, for which a 10% aqueous solution was crushed into the well bottom zone) and (- a 2.5 m generator with a subsequent displacement of 15 m of fresh water. In a number of cases, the concentration of ions Calcium in the formation water exceeded 5000 mg / l; negative results were obtained.

Skvakina t 206 treatment at the Sultangulovsko-Zaglinskoe deposit was not completed according to the above procedure, since the well bottom zone was filled with a gel-like l-calcium inhibitor salt. L wells No. 214 and N 217 were treated with the Corexit-7647 inhibitor, but this led to a sharp decrease in the productivity of the wells (partial isolation of the wellbore zone by the product of the interaction of the inhibitor and ionic calcium) occurred.

The aim of the invention is to increase the efficiency of wellbore zone treatment by eliminating the occurrence of incompatibility of a scale inhibitor with saline formation waters containing calcium ions.

This goal is achieved by the fact that a chelating agent is crushed into the wellbore zone, followed by a solution of a scale inhibitor or a chelating agent

the inhibitor is supplied simultaneously. The concentration of the scale inhibitor is in the range of 10-20% by weight. An organic nitrogen-containing complexone is used as a chelating agent, capable of forming soluble complexes with anion-containing ions (ethylenediaminetetraacetic acid-trilon-in disodium salt)

NaQoc-CH

CK -coowa

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, N-CK,

ioos - n.

, j-COOH

The occurrence of the positive effect observed when using the proposed invention can be explained as follows. Injection into the wellbore zone of the inhibitor well at a concentration of 10–20 wt.% Of the active substance is practically impossible at a calcium ION concentration of 3000 mg / l and more. The introduction of a chelating agent plast plate into the retinue, both prior to the introduction of a scale inhibitor, and together eliminates the disadvantages of the prototype method. A chelating agent is introduced in such an amount that the calcium ions are bound by the complexone, and the injected inhibitor at a given concentration would be compatible with the formation waters. The ratio of scale inhibitor to chelating agent is determined experimentally for each well, taking into account the economic feasibility of adjusting the volume of water injected into the formation, the amount of chelating agent added, or both. It is important that the water system

The saltwater inhibitor solution was completely compatible.

Table 1 shows the laboratory data for assessing the compatibility of model reservoir waters with: a Scalexit-7647 scaling inhibitor solution, the concentration of which is 10% of the active substance:

V model reservoir water: V scaling inhibitor 1: 1.

Compatible solutions are considered in the case when, after draining both solutions, the resulting solution has no sediment and turbidity. Compatibility assessment is made visually.

From the data given in Table 1, it follows that the model reservoir waters containing calcium ions from

5000 mg / l. and above, are not compatible with the AND {) salt scale accumulator at a concentration of 10 wt.%. The sodium and magnesium ions do not affect the compatibility of the scale inhibitor.

 mrdelnom reservoir waters. Table 2 presents data on assessing the compatibility of model reservoir water (calcium ion concentration from 5000-30000 mg / l) with an injected scaling inhibitor. Compatibility control is carried out by feeding a chelating agent into the system prior to the introduction of a scale inhibitor, together with a scale inhibitor. From the data presented in Table 1, it follows that it is advisable to use the disodium salt with ethylenediami of tetraacetic acid as the chelating agent. Compatibility is complete when applying a chelating agent to or along with a scale inhibitor. Fully compatible with calcium ion concentrations in formation water from LOOO-30000 mg / l. The concentration of Trilon-B, necessary for the complete overlap of model reservoir water and a scale inhibitor in the entire range of calcium ion traction, is in the range of 0.3-10.0 wt.%. The presented data cannot be considered as a composition, as the range of concentrations of Trilon-B 0.3 10.0 wt.% Is not valid for the whole range of concentrations of calcium ions (5000-30000 mg / l). The data table. There are specific cases in the choice of chelating agent concentrations depending on the concentration of calcium ions (water content is up to 100 wt.%). For example: the concentration of Trilon-B is 9.3 wt. %, valid for the entire range of concentrations of calcium ions, and 0.3 weight. % - only for one value equal to 500 mg / l. Example. In 50 cm of mineralized water (reservoir) well 113 of the Krasnoroye field of PGD Buguruslanneft with a calcium ion concentration of 100036 mg / l, 50 cm of 10% aqueous solution of the scale inhibitor Corexit-7647 and 1.8 wt. % Trilon-B. EXAMPLE 2. In 50 cm of mineralized reservoir water from the well of the Krasnoyarsk field, the PGUU Buguruslanneft, with a calcium ion concentration of 10036 mg / l, was introduced to reduce 1.8 weight. % Trilon-B, and then 50 cm of 10% pacTBQpa salt degradation inhibitor Corexit-7647. Example 3. In 50 cm of mineralized reservoir water from the well 11 of the Krasnoroye field of the NGDU Buguruslanneft oil with a concentration of calcium ions of 10036 mg / l, 50 CNt of a 15% aqueous solution of the scale inhibitor Corexit-7647 and 2.0 wt. % Trilon-B. Example4. At 50 cm of mineralized reservoir water: the wells of the 113 Krasnorsk deposit, GDU Buguruslanneft with a calcium ion concentration of 10036 mg / l, 2.0 weight was introduced. % Trilon-and, and then 50 cm of a 15% solution of scale inhibitor Corexit-7647. Example5. 50 cm of the mineralized reservoir water from the well 113 of the Krasnoyarsk field of the NGDU Buguruslanneft, with a concentration of calcium ions of 10036 mg / l, 50 cm of scale inhibitor Corexit-7647 with a concentration of 20% and 2.1 weight were injected. % Trilon B, Approx. B50 cm of mineralized reservoir water from the well 1.13 of the Krasnororsky field, IGDU Buguruslan, eft, with a calcium ion concentration of 10036 mg / l, 2.1 wt. % Trilon-B, and then 50 cm of a 20-th solution of scale inhibitor Koreksit-7647. In all cases, the compatibility of mineralized formation water and a scale inhibitor with the addition of a chelating agent is complete. For comparison, similar work was carried out according to the prototype method. When a scale inhibitor Korexit-7647 is introduced into the saline water of a reservoir, even at concentrations of 1–2%, solution drains, which indicates the incompatibility of these solutions. 7In this way, the proposed method fully implements the purpose of the invention, namely: full compatibility of saline stratum waters with the scale inhibitor introduced into the formation of the formation is achieved; the method allows the injection of an inhibitor with a higher concentration; reduced volumes of water injected into the reservoir; fresh water consumption is reduced. The scale inhibitor Korexit-7647 is present in significant quantities in the enterprises of the Orenburgneft association, and Trilon-B is a non-deficient product produced by the domestic industry in significant quantities for clearing the calves. The expected economic effect from the use of the proposed method only in the Orenburgneft system is 130,000 rubles per year.

.Table 1

Continued table. 2

Claims (4)

Invention Formula A method for preventing salt deposition in a well and skazhinny equipment by pumping a scale inhibitor into the wellbore zone of the well, so that, in order to improve the effect / evidence of the method by eliminating the incompatibility of scale inhibitor with mineralized formations waters containing calcium ions, a chelating agent is introduced into the formation, 2. The method according to claim 1, wherein the supply of a chelating agent is carried out prior to pumping the scale inhibitor or together. 3. The method according to claim 1, wherein a disodium salt of ethylenediaminetetraacetic acid is used as a chelating agent. 4. The method, according to claim 3, of which is that the chelating agent is administered in an amount necessary for the complete binding of the ions of the formation water, Information sources, taken into account in the examination 1. Reference book on oil production. Ed. U.K. Himatudinova, M., Nedra, 1974, p. 613. 2, Use of Corexit 7647 in the USSR. Prospect of the company Esso Chemicals, p.5.