JPS62256722A - Method of controlling and delaying formation of gel or sediment derived from aluminum and corresponding compositionand application to oil well - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a composition for retarding and controlling the formation of gels or precipitates derived from aluminium. Applied.

[Prior art and problems] No. 4, jl!, which produces hydrocarbons from geological formations. ! It is often the case (preferably) that the permeability of some areas in the Fl is reduced. This is the case, for example, when formations adjacent to a producing oil well tend to channel water into the well. Another example is when there is a highly permeable area adjacent to the injection well.

A first method of reducing the permeability of some underground areas consists in precipitating the product in situ. This technique is well known and is usually carried out by placing two incompatible liquids in one oil layer. As a result, a precipitate is formed where the two liquids come into contact with each other and mix inside the oil layer, reducing permeability. Those skilled in the art are referred to US Pat. No. 3,837,400, US Pat. No. 4,031,958, and US Pat.

The second method consists in introducing a liquid that reacts with specific components such as inherent water in the oil layer to form an insoluble precipitate. Those skilled in the art are referred to US Pat. No. 3,837,400.

Yet another method consists in introducing a liquid that has an inherent potential to form a precipitate or gel.

However, this formation requires some means of retarding action. Those skilled in the art are referred to US Pat. No. 4,413.680 and US Pat. No. 3,614,985.

To carry out this task successfully, it is important to control two parameters: the retardation effect required during the formation of the gel or precipitate, and the morphology of the solid phase formed. The retardation effect on time determines the degree of possible penetration into the formation, and the morphology of the solid phase determines the degree of reduction in permeability of the formation.

US Pat. No. 2,614,985 describes a precipitation process starting from a homogeneous solution of a metal hydroxide, such as chromium hydroxide or aluminum hydroxide.

Many simple salts of aluminum III (such as aluminum chloride or aluminum nitrate) are soluble in mildly acidic media, but form insoluble aluminum hydroxide at pH levels above about 5. The aforementioned patent describes a method for the delayed formation of aluminum hydroxide type compounds by using a solution consisting of a suitable aluminum salt and an activator. This activator is used to gradually increase the solution pH level 5 in the temperature range typically present at the bottom of an oil well. 29 results in delayed formation of an insoluble hydroxide phase. As described in this patent, a suitable activator is urea, which is hydrolyzed at high temperatures to form ammonia, which increases the pH of the solution. In this way the solid aluminum hydroxide precipitate phase tends to remain amorphous and has the appearance of a gel.

The only example of the process described in the aforementioned patent concerns the precipitation of aluminum hydroxide starting from aluminum chloride. However, as described in this patent, this solution is unsuitable for use in oil field operations both from a safety point of view and from the point of view of technical constraints. This is because aluminum chloride reacts violently with water in the solid state, generating heat and hydrochloric acid vapor.

Therefore, operation of this system in oil fields is extremely dangerous. Additionally, the use of concentrated solutions of aluminum chloride is undesirable due to the volume of liquid required and the need for corrosion inhibitors to protect the metering pumps, which often adversely affect well treatment. It is known to give country.

Typical treatment solutions (approximately 0.05-0.15M
Al 3+) has a pH of about 3, and it is preferred to adjust its pH to about 4, as recommended by the above-mentioned patent, in fact the pH is 3.

Reaction with carbonates in porous media is extremely rapid, limiting liquid penetration into the matrix.

Even for very pure sandstones where the reaction with carbonates is not intercalated, a pH of 4 is preferred since a pH of 3 requires a high concentration of urea to initiate the precipitation reaction.

Unfortunately, when using the system described in the aforementioned patent,
This pHW:4 adjustment is impossible. Or even if it is possible, it is not practical. In fact, the addition of an alkaline agent to a typical aluminum chloride solution immediately and unavoidably produces a precipitate, which slowly dissolves over time.
Because it increases H.

The presence of alkaline agents requires the use of discontinuous mixing techniques. This mixing technique can only be carried out for large quantities of liquid and requires days or weeks, especially since this operation is carried out in a very limited area. The precipitate will only be redissolved if fresh water is available. If the mixed water used is not pure and contains salts, such as salt water or seawater found in oil fields, the addition of an alkaline agent will prevent the initially formed precipitate from dissolving for a long time (by stirring vigorously at high temperatures). ), although such cases are often seen,
The problem is not resolved.

A seventeenth aspect of the invention resides in the use of aluminum hydroxychloride as the "plugging agent". This polymeric salt is commercially prepared by hydrolysis of aluminum chloride solutions. In its crystalline form, the formula: have

(A12 (OH)q C1,'2.5H20)nMore generally, this compound is in the form of an acidic aluminum salt having the general formula:

Second, X is an inorganic or organic anion (or a mixture of inorganic and organic anions), and (pxq) +
m=3n, q is the valence of the anion, and the ratio (m/
3n) xloo defines the basicity of the salt and is 30-80%
It's between.

The method of using aluminum hydroxychloride as a bragging agent solves the problems observed with the prior art and also offers various new possibilities, in particular with regard to effective control of gelation time or precipitation and monitoring of the morphology of the precipitate. .

Note: If the highly permeable zone to be treated is an entirely porous matrix, a solid phase consisting of an elastic gel is preferred and appears to be most effective in reducing the flow rate inside this zone.

1. If the high permeability zone is due to a porous matrix and fractures, solid particulate granules are preferred, in which case the granules formed in the fractures are
The flow collects on the surface of the fracture and the corresponding area is sealed.

Aluminum hydroxychloride 11 rapidly and completely solves this problem without producing high levels of heat or hydrochloric acid gas. This in itself is a major improvement in terms of safety. In addition, aluminum hydroxychloride is
! 2 It is obtained as a u1 aqueous solution when liquid injection is absolutely necessary at the excavation site, and this polymeric salt has a
It has the added advantage of being approximately twice as concentrated as commercially available aluminum chloride solutions, which only have a pH of .

As previously mentioned, the excessively low pH levels of prior art aluminum chloride (typically 2.8-3.2) make it virtually impossible to use aluminum chloride fluids in carbonate-containing sumps. It meant that. This is because the precipitates that form in that case immediately cause blockage of the oil well, something that must be avoided at all costs.

Problems also arise in the case of pure sandstone. This is because sandstone contains a certain percentage of carbonate, and in order to obtain sufficient penetration of liquid, it is preferable that the initial pH is around 4 or 4.5. This pH level reduces undesirable interactions between the liquid and the oil and also reduces the amount of urea required to initiate the precipitation reaction.

It should also be noted that it is virtually impossible to raise the pH level (by any practical means) of a single aluminum salt using an alkaline agent as described in the aforementioned U.S. Pat. No. 3,614,985. Must be.

As a practical matter, precipitation of aluminum hydroxychloride occurs immediately and it is necessary to use discontinuous mixing techniques. In that case, it becomes impossible to maintain a suitable Huni rate for several days, which is an unacceptable constraint.

The use of aluminum hydroxychloride and an activator such as urea provides a solution to these problems.

This is because this polymer salt is completely dissolved and has a 4 to 4.5
This is because it forms a solution with a pH level of , which ensures sufficient penetration into the oil layer without the need for discontinuous techniques. On the contrary, continuous mixing techniques become possible.

Other aspects of the invention show the possibility of using other weak bases in place of urea as activators, together with aluminum hydroxychloride, in particular the invention shows that hexamethylene-
The use of an activator consisting of tetramine and aluminum hydroxychloride as plugging agent is proposed.

The following examples are intended to illustrate the invention, but are not intended to limit it, and the test results were obtained for urea and hexamethylene-tetramine.

It is known that two parameters are of paramount importance when attempting to reduce the permeability of porous media using the aforementioned techniques. These parameters are the reaction time and the morphology of the precipitate.The reaction time determines the possible penetration distance into a given oil reservoir, whereas the morphology of the solid phase determines the permeability of the porous medium. Determine the degree of decline.

When using the present invention, certain compounds, when used with urea, have an unexpected but very necessary effect on the various aluminum hydroxide precipitation reactions resulting in said hydrolysis reactions. It has been possible to accelerate or retard the reaction by using the catalytic converter to adapt the morphology of the solid phase produced, and to form morphologies ranging from amorphous gels to dense small crystals.

The catalysts useful in the process of the invention affect the reaction time and the morphology of the solid phase and are generally 7-ions, more generally polyvalent anions such as tartrate,
citrate, sulfate or lactate. Each of these ions gives a different shape to the solid phase morphology and reaction time, as shown in the Examples below.

Most polyvalent anions are accelerators and therefore greatly reduce the time to precipitate solids from solution. Citrate and tartrate are the most active, but anions such as oxalate, sulfate and lactate also have a promoting effect.

The examples below are not intended to limit the invention, but rather provide the necessary information for the selection of products and suitable additives to obtain the desired results for each mining site.

"Rocron" is a solid aluminum hydroxychloride corresponding to the above formula and is commercially available from Hoechst GmbH, Federal Republic of Germany.

The percentages shown in each example are percentages by volume unless otherwise specified.

The symbols used in the table below are as follows.

GG: Good gel WG: Weak gel BG: Broken gel NG No gel S: Syneresis C: Cloudy liquid C1: Clear solution J: Days h: Time The most used solution was 3% aluminum hydroxychloride ( A
HC) and 3% urea in distilled water. First PH
= 4.2, gel time was approximately 3 days at a temperature of 65"C (149°F).

-Δ+n-1勺... The solution used was a solution of 3% urea and 5% aluminum hydroxychloride in distilled water. The initial pH was 4.2° and the gelation time was approximately 80 hours at a temperature of 149°F.

---U of 2''L The solution used was a solution of 3% AMC and 1% urea in distilled water. The initial pH was 4.2°, the temperature was 149°F and the gel time was about 6 days.

1------- The solution used was 3% AI (NaCl with C and 3% urea).
It was a solution.

At a temperature of 65° C. (149@F) the gelation time is approximately 100° C. Many anions, especially divalent anions, have a promoting effect in the reaction.

Below are some examples of these additives.

1. Standard solution = 3% aluminum hydroxychloride (
AHC) and 3% urea solution, pH = 4°3, temperature = 6
5℃ (149'F) This mark P! For solution, the above reaction formed a solid gel after a gelation time (Gt) of 72 hours.

2-Standard solution + sodium sulfate O, OIM; Gt=35
h.

3-Standard solution + sodium sulfate 0.03M; Gt=20
h.

4-Standard solution + phosphoric acid 0. OIMHGt=40h.

5-Standard solution + cunic acid 0,03 M; G t
= 30h.

6-Standard solution + tartaric acid 0. OIM; Gt = 48h7-standard solution + tartar u0.03M; Gt = 35h8-Sitei solution + sodium fluoride ○, ○LM; G = 52h.

9-Standard solution + sodium fluoride 0.03M: Gt=4
0h 10-standard solution + Shu ao, oIM; Gt = 42h.

11-Stock solution + oxalic acid 0.03M; Gt = 33h.

12-Standard solution + fumaric acid O, OIM; Gt=55h.

13-fi cram school solution +77/L/acid 0.03M; Gt=
38 hours.

14-Shibeichi solution + erythorbic acid 0. OIM;Gt=5
5h.

15-standard Qi solution + erythorbic acid 0.03M; Gt
=46 h.

Additives having a tendency to form fine crystal particles are called "crystallizing agents".

If necessary, gelling agents can be used to compensate for the effect of crystallizing agents naturally present in the mixing water.

Preferred gelling agents are citric acid and tartaric acid.

Preferred crystallizing agents are a-acid, oxalate and succinic acid.

Gelling agents and crystallizing agents can be used separately or in combination to adapt the composition to various special situations.

6 -Me・-S (a) Core sample: Consolidated sandstone diameter: 5CIT+ Length: 15cm Initial permeability (3%NaCL) LL5mD Final permeability (3%NaCl) -53mDb) Core sample: Consolidated sandstone diameter: 5cn Length Size: 15cm Initial penetration rate (3% NaC1,) - 420mD Final penetration rate (
3% NaCl)-126mDC) non-condensing sand pack (
Diameter: 8C+++ Length: 30c1 Initial permeability (3% NaC1) - 1663 mD Final permeability (3% NaC1) - 130 mDd) Non-condensing sand pack (i.e. tube filled with non-condensing sand) Pipe) Diameter: 80:n Length: 550II+ Initial penetration rate (3% NaCL) - 2360! 11D Final penetration rate (3% NIIICI) - 49 mDe) Non-condensation sand pack (i.e. tube filled with non-ig condensation sand) Diameter : 8cm Length: 55cm Initial permeability (3% NaC1) - 9843 mD Permeability after 1st treatment - 3250 mD Permeability after 2nd treatment - 1004 m D The coagulated core sample is Fontainebleau sandstone. The sand pack was a mixture of various types of Fontainebleau sand and Ottawa sand.The treatment method was to inject the standard solution added with 5% citric acid into half of the pore volume; After a sufficient period of time for solid phase formation, the injection should be stopped.

Nakagami-guchi RO + ” Variables: N a C1% test @ degree Rokuron, hydroxyaluminum chloride, urea ε and N
a Various solutions containing C1 were prepared and their temperature was raised to the "test °" temperature.

observed to detect whether a gel was formed (“
Bintest′).

The composition of the solution, the test temperature, and the results after each time or number of days are shown below.

1 RO + N a CL, Ca Cl 2 or seawater moss l-1W
Temperature: 80"C (176@F) Test method is similar to Example 8 above.

The Rocuron (aluminum hydroxychloride) concentration is 3% by volume of the solution, as is the urea concentration.

The composition of the seawater used is shown in Table VIE below.

Results obtained after a certain period of time, and N a Cl and Ca
The Cl2% is shown in Table VIII below.

Test temperature: 80℃ (176@F) NaC1: 1% The test method was the same as in Examples 8 and 9 for forward bending.

Use fA degree: Rokron -3%; Na Cl -1%
.

The composition used and the results after a certain period of time are shown in Table IX below.
Shown below.

In addition, a single graph (attached figure) shows 1%N a C1 and 3
Figure 2 shows the gelation time (at 80 DEG C.) of solutions containing % chloride as a function of hexamethylene-tetramine concentration.

These tables can be used by those skilled in the art to select optimal parameters to suit given well conditions, e.g., to accommodate processing temperature constraints.

One of the main advantages of the composition according to the invention lies in its compatibility with saline media.

The presence of salts (N a Cl , seawater and especially polyvalent calcium and magnesium salts) causes serious problems in prior art treatments, for example when using polyacrylamide. For such polymers, Ca or Mg
If more than 400 or 500 ppm of salt is present, the treatment will not be effective.

On the other hand, the composition according to the invention can be used in the presence of a salt content of a few percent (including calcium salts) or in the presence of seawater, which expands the possibilities for offshore drilling operations.

Claims (1)

Claims: 1. Retardation of the process of forming an aluminum-derived gel or precipitate by reacting an aluminum-derived starting product with an "activator" in an aqueous medium to form a gel or precipitate. In a controlled process, the starting product is an acidic aluminum salt (partially neutralized) having the general formula Al_n(OH)_mX_p where X is an inorganic or organic anion (or an inorganic or organic anion). mixture), and (pxq)+m=3
A method characterized in that n and q are the valences of the anion, and the ratio (m/3n) x 100 determines the basicity of the salt and is within the range of 30 to 80%. 2. Process according to claim 1, characterized in that the starting product is aluminum hydroxychloride having the formula: Al_2(OH)_5, 2.5H_2O3, aluminum hydroxychloride starting product is reacted in an aqueous medium in the presence of urea acting as an activator to precipitate the aluminum hydroxide type in the form of a gel or finely crystalline particles. A method according to either claim 1 or 2, characterized in that it produces a product. 4. Claim 1, characterized in that the starting product of aluminum hydroxychloride is reacted in an aqueous medium with hexamethylene-tetramine as an activator.
The method according to either paragraph or paragraph 2. 5. The precipitation reaction activator is a substance that releases anions, such as sodium sulfate, citric acid, tartaric acid, sodium fluoride, oxalic acid, fumaric acid, or erythorubic acid. Claim 1 A method according to any one of Items 1 to 4. 6. The morphology of the precipitate (gel or fine particles) is selected by using gelling additives or crystallizing agents, in particular: - the gelling agent is an anion such as citrate or tartrate; - the crystallization 6. The method according to claim 1, wherein the curing agent is an anion such as sulfate, oxalate, and succinate. 7. Gels or particles containing a starting product of the hydroxyaluminum chloride type according to claim 1 or 2, characterized in that they are used together with urea or hexamethylene-tetramine as activator. A delayed precipitation type composition is produced. 8. A composition according to claim 6, characterized in that it additionally contains a promoter and/or a gelling agent and/or a crystallizing agent selected from the following: - Accelerators: sodium sulfate, citric acid, tartaric acid. anions such as sodium fluoride, oxalate, fumarate or erythorbate; -gelling agents: anions such as citrate and tartrate; -crystallizing agents: such as sulfate, oxalate, and succinate. Crystallizing agent. 9. According to any one of claims 1 to 7, in which the product is injected into an oil well, gas well, or water well to stop a specific underground layer penetrated by these wells. Application of the method or composition.