JPH066701B2 - Pressurized fluid composition for oil recovery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an aqueous injection fluid composition used in a method for increasing recovery of petroleum, and more particularly, to improve oil recovery with a small amount of surfactant. It relates to a stabilized aqueous pressurizing fluid composition.

(Prior Art) Various types of increased oil recovery technologies have been proposed and implemented as methods for artificially recovering unrecovered oil from existing oil fields. In particular, a surfactant, an alkaline substance, or a high molecular substance alone is used. A method for recovering petroleum, which is used or a combination thereof, has been proposed as a promising method for improving recovery rate.

Among the methods using a surfactant, there is a petroleum recovery method generally known as a micellar flooding method using a so-called micellar solution containing a surfactant, a hydrocarbon, a surfactant and a water as main components. . Since the micellar solution is excellent in oil replacement efficiency, the micelle flooding method usually has a high oil recovery rate, but has a problem of high cost and low economic efficiency.

On the other hand, a method for recovering petroleum using an aqueous solution of an alkaline substance alone or an aqueous solution of an alkaline substance mixed with a water-soluble polymer substance has been proposed. This method is commonly known as alkali flooding or alkali polymer flooding.
Although the cost of the chemicals used in this method is low, there is a problem that the recovery rate of oil is low.

As described above, as a method for recovering petroleum and a chemical used for recovering petroleum, it is strongly desired that the cost is low and the economy is high, and at the same time, the recovery rate of petroleum is high.

As one of the methods, there is a method of using an aqueous solution in which a surfactant such as a sulfuric acid ester of an ethoxylated higher alcohol is added to a mixed aqueous solution of an alkaline substance and a polymer substance. C. Proposed by RC Nelson et al. [S. Pee. E / D. Oh. E-paper (SPE / DOE Paper) NO.12672].

Also, M. J. Research by MJ Pitts and others [Petrolium Society of S. Eye.
M. Paper] (Petroleum Society of SIM Papae
r) NO.86-37-53], an aqueous solution containing 0.1% by weight of petroleum sulfonate in an aqueous solution containing 0.8% by weight of sodium hydroxide has an interfacial tension of Grand Forks petroleum of 10 ^-3 dyne / cm. It is stated that the oil recovery rate was high by using an aqueous solution in which the above composition was mixed with a polyacrylamide-based polymer substance.

(Problems to be Solved by the Invention) However, when the present inventors blended petroleum sulfonate, an alkaline substance, and a water-soluble polymer substance for mobility adjustment, which are usually used for recovering petroleum, as a salt aqueous solution, the composition was It was found to be unstable and form a precipitate. Nelson et al. And Pitts et al. Have not proposed anything to prevent this precipitation.

A composition comprising surfactant used for oil recovery shown in reports such as Pitts-alkaline substance-polymeric substance-water, for example, 0.3% by weight of petroleum sulfonate (based on active ingredient), 0.5% by weight of sodium hydroxide In a composition consisting of 0.2% by weight of a polyacrylamide polymer and 99% by weight of water, the system is unstable and forms a precipitate even if it contains 0.1% by weight of salt based on water.

When an alkylaryl sulfonate is used instead of petroleum sulfonate in a similar composition, or when the hydrolysis rate and / or the molecular weight is changed in a polyacrylamide polymer, and when the polyacrylamide polymer is replaced by a water-soluble substance generally known as xanthan gum. Similarly, satisfactory results cannot be obtained when a polymer substance is used.

(Means for Solving the Problem) On the other hand, the injection fluid composition for petroleum recovery provided by the present invention is essentially stable and uniform, although some examples will be shown in Examples described later.

The present inventors have conducted extensive studies in consideration of the above-mentioned problems, and as a result, have an excellent ability to reduce the interfacial tension of petroleum, are stable, and have a mobility adjusting ability. Invented a composition.

That is, the present invention provides a liquid composition for use in recovering petroleum, which contains a surfactant, an alkaline substance, water which may contain an inorganic salt, and a water-soluble polymer substance for mobility adjustment. The present invention relates to a pressurizing fluid composition for petroleum recovery, which has a stable interfacial tension lowering ability, is stable, and has a mobility adjusting effect, in which a sufficient amount of an auxiliary agent is added to stabilize the product so as not to cause precipitation. is there.

The surfactant used in the practice of the present invention may be of any type, and is a desirable aqueous pressurizing fluid in consideration of the salinity of the oilfield water of the target oilfield and / or the water used and the properties of petroleum. The choice is made to obtain the composition. Most preferably, at least one type of petroleum sulfonate or alkylaryl sulfonate having an average equivalent weight of about 350 to about 550 is used. These petroleum sulfonates and alkylaryl sulfonates may be petroleum sulfonates and alkylaryl sulfonates produced by known methods described in, for example, JP-A-55-500119 or JP-A-61-264082, and are mainly Alkali metal salts or ammonium salts are preferable, and they may contain a polysulfonation product, an inorganic salt and an unreacted hydrocarbon in addition to the monosulfonation product as the main component.

The amount of the surfactant used depends on the kind of petroleum, but in order to make the interfacial tension between the press-fitting fluid and petroleum about 100 millidyne / cm or less, the concentration of the active ingredient is 0.01% by weight or more. Further, even if the amount of the surfactant active ingredient exceeding 2.0% by weight is used, the effect is not so different.

Thus, the composition provided by the present invention can use the known petroleum sulfonates and alkylaryl sulfonates as surfactants.

The alkaline substance used in the present invention can be any known compound capable of exhibiting alkalinity when dissolved in water. For example, NaOH, NH ₄ OH,
There are KOH, Na ₂ CO ₃ , K ₂ CO ₃ , Na ₄ SiO ₄ or mixtures thereof. At least one alkaline substance can be selected in view of the salinity of the target oilfield water and / or the water to be used and the nature of the petroleum to obtain the desired petroleum recovery injection fluid composition according to the present invention. .

The injection fluid composition for oil recovery provided by the present invention contains a water-soluble polymer substance as a component for efficiently and uniformly recovering oil from the entire underground oil-bearing layer by using the composition.

The water-soluble polymer substance may be a known substance. For example, polyacrylamide which may be partially hydrolyzed, heteropolysaccharide produced by microorganisms such as xanthan gum, hydroxyethyl cellulose, carboxymethyl cellulose and the like can be mentioned. The molecular weight of the water-soluble polymer substance and the amount used are selected so as to give an appropriate viscosity as a press-fitting fluid.

In the oil recovery pressurizing fluid composition of the present invention, the solution stabilizing aid serves to stabilize the composition without causing precipitation. The auxiliary agent used in the present invention is at least one selected from the group consisting of polyethylene glycol ether, α-olefin sulfonate and alkylaryl sulfonate.

The polyethylene glycol ether is an organic species (ethoxylates) to which at least one polyethylene glycol chain is added in the molecule, preferably polyethylene glycol alkyl ether, polyethylene glycol alkenyl ether, polyethylene glycol alkylphenyl ether, sorbitan. Examples thereof include polyethylene glycol ethers of fatty acid esters and polyethylene glycol polypropylene glycol block copolymers.

Examples of these ethoxylates include polyethylene glycol lauryl ether, polyethylene glycol cetyl ether, polyethylene glycol stearyl ether, polyethylene glycol oleyl ether,
Polyethylene glycol nonyl phenyl ether, polyethylene glycol octyl phenyl ether, polyethylene glycol dodecyl phenyl ether, polyethylene glycol sorbitan monolaurate, polyethylene glycol sorbitan monostearate, polyethylene glycol sorbitan monopalmitate, polyethylene glycol sorbitan monooleate, polyethylene glycol sorbitan trioleate And polyethylene glycol polypropylene glycol block copolymers.

The above-mentioned α-olefin sulfonate and alkylaryl sulfonate are known sulfonates having an average equivalent weight of about 350 or less.

In the present invention, the auxiliary agent needs to be added in an amount sufficient to stabilize the composition containing an alkaline substance, a surfactant, and a water-soluble polymer substance without causing precipitation, and the addition amount is It depends on the kind of the surfactant in the composition, the salt concentration of water to be used and the kind and concentration of the alkaline substance, and the kind of the auxiliary agent itself, but usually 100 weight% of the active ingredient of the surfactant in the composition. Amounts of up to 100 parts by weight of active ingredient of auxiliary agent are used per part.

Addition of auxiliaries is necessary to obtain a stable press-in fluid composition containing the water-soluble polymeric substance, the alkaline substance and the surfactant provided by the present invention, while the use of the auxiliaries is required for the composition. Increase costs and reduce economic efficiency. Therefore, the amount of the auxiliary agent added is preferably 50 parts by weight or less per 100 parts by weight of the active ingredient of the surfactant blended in the composition.

(Effect of the present invention) Since the pressurizing fluid composition for oil recovery of the present invention is essentially stable, it is possible to carry out the oil recovery process stably on an industrial scale. The amount of surfactant used is low and the cost is low. It is economical because it is cheap, has excellent ability to reduce interfacial tension, has a high oil recovery rate, and so on.

(Examples) Detailed examples of the present invention will be shown below, but these examples do not limit the scope of the present invention. Further, various modifications made within the scope of the present invention are included in the scope of the present invention. The concentrations of surfactants and auxiliaries in the examples are based on the amount of active ingredients.

Example 1 Using water containing 0.5% by weight of NaOH and 0.5% by weight of NaCl based on water, 0.3% by weight of alkylaryl sulfonate having an average equivalent weight of about 395 and polyacrylamide having an average molecular weight of about 10 million (hereinafter referred to as PAM-A). When was mixed in an amount such that the viscosity of the composition was about 50 cp, the liquid composition was unstable and precipitation occurred. On the other hand, by incorporating the auxiliaries according to the invention, the composition was stabilized and the formation of precipitates did not occur. An example is shown below. The viscosity was measured at 45 ° C. using a Brookfield viscometer.

Comparative Example 1 In the same system as described above, a stable composition could not be obtained even if the surfactant concentration was changed and no auxiliary agent was added.

Surfactant concentration Auxiliary agent Stability 0.1 wt% None Precipitate formation 0.3 wt% None Precipitate formation 1.0 wt% None Precipitate formation Comparative Example 2 In the same system as above, the surfactant concentration was fixed at 0.3 wt% A stable composition could not be obtained without changing the type of auxiliary agent, even if the type was changed. The concentration of the polymeric substance was selected so that the viscosity was 50 cp at 45 ° C.

Example 2 In the system described in Example 1, it was possible to obtain a stable composition by adding an auxiliary agent according to the present invention even when other kinds of surfactants were used. The results are shown below.

Example 3 An example of using various concentrations of the alkylaryl sulfonates described in Example 1 and adding polyethylene glycol nonylphenyl ether (ethylene glycol average addition mole number about 95) as an auxiliary agent according to the present invention is shown below.
It was possible to obtain a stable liquid composition without precipitation even with an additive amount of 0.075% by weight. The results are shown in the table below. The concentration of the polymer substance was selected so that the viscosity of the composition was about 50 cp at 45 ° C.

Sample Surfactant Auxiliary agent Example 4 An example is shown in which the auxiliary agent is changed to an alkylaryl sulfonate having an average equivalent weight of about 320 in the system described in Example 1, but a stable composition can be obtained only by adding the auxiliary agent according to the present invention. did it. The results are shown in the table below.

Sample Number Surfactant Concentration Amount of Auxiliary Stability 11 0.15% by weight None Precipitation 12 0.15% by weight 0.15% by weight Stable Example 5 It was shown that a stable composition was obtained according to the present invention Example 1
As described above in Example 4, the stable injection fluid composition for oil recovery provided by the present invention can efficiently reduce the interfacial tension with oil. As an example, API specific gravity of about 3
The interfacial tension values measured by the spinning drop method using paraffin base crude oil at 3 ° are shown in the table below.

The concentration of the polymer substance was selected so that the viscosity of the composition was about 50 cp at about 45 ° C.

Example 6 The injection fluid composition for oil recovery of the present invention illustrated in Examples 1 to 5 is essentially stable and can effectively reduce the interfacial tension with oil. Therefore, when the stabilized injection fluid composition for oil recovery provided by the present invention is used in the oil recovery process, a high oil recovery rate can be obtained. An example of a petroleum oil recovery test is shown.

A berea sandstone core with a permeability of about 200 md and a porosity of about 20% was used for the oil recovery test. In the test, a core fully saturated with brine was loaded into a holder, and paraffin base crude oil having an API specific gravity of about 33 ° was injected at a rate of 10 feet / day until the brine did not flow out. Subsequently, brine was injected at a rate of 0.5 feet / day to carry out a water attack to recover the oil. At the end of the water flood, the amount of petroleum in the effluent was trace.

The composition according to the principles of the present invention was subsequently 100% pore volume pressed, followed by brine at about 150% pore volume pressed. The injection speed was 0.5 feet / day.

When the amount of recovered oil was evaluated, the oil recovery rate was 63% of the residual oil after the water attack. Incidentally, the oil recovery rate was only 43% with the same composition containing no solution stabilizing aid.

Claims (5)

[Claims] 1. At least one solution stabilizing aid selected from the group consisting of polyethylene glycol ether, an α-olefin sulfonate having an average equivalent weight of about 350 or less and an alkylaryl sulfonate having an average equivalent weight of about 350 or less, a surfactant, and an alkalinity. A pressurizing fluid composition for petroleum recovery comprising a substance, water optionally containing an inorganic salt, and a water-soluble polymer substance for adjusting mobility. 2. The polyethylene glycol ether is
The composition according to claim 1, which is selected from polyethylene glycol alkyl ethers, polyethylene glycol alkenyl ethers, and polyethylene glycol alkyl phenyl ethers. 3. The composition according to claim 1, wherein the polyethylene glycol ether is a polyethylene glycol ether of sorbitan fatty acid ester. 4. The composition according to claim 1, wherein the polyethylene glycol ether is a polyethylene glycol-polypropylene glycol block copolymer. 5. The surfactant according to claim 1, which is an alkylaryl sulfonate and a petroleum sulfonate.
The composition according to any one of items 1 to 4.