Process for sand and proppant consolidation

Abstract

A process for consolidating sand, proppant and other suspended particles present in a subterranean reservoir using an aqueous emulsion particle consolidation system is described. Surfactants with cloud points at or below the reservoir temperature are used to make a low viscosity aqueous external emulsion system with resin and curing agent as the internal phase. As the surfactant reaches its cloud point, it loses its emulsification ability and releases the resin and curing agent to consolidate the sand. The aqueous phase of the system then functions as a spacer to maintain the permeability needed for oil and gas production without additional post flush required.

Claims

1. A process for the consolidation of particles that includes preparing an aqueous emulsion particle consolidation composition containing: a. one or more surfactants having a cloud point at or below the reservoir temperature, b. one or more resins, c. one or more curing agents, e. an aqueous solvent, dissolving the one or more surfactants in the one or more resins adding the aqueous solvent to form a water external emulsion, adding one or more curing agents, introducing the composition into a subterranean reservoir; and; allowing sufficient time for the composition to cure.

2. The process described in claim 1 where the one or more surfactants having a cloud point at or below the reservoir temperature is selected from the group nonionic surfactants.

3. The process described in claim 1 where the one or more resins is selected from the group bis-phenol A diglycidyl ether, bis-phenol F diglycidyl ether, cycloaliphatic epoxides, furfuryl based epoxies, glycidyl ethers, poly glycidyl ethers, novalac resins, polyurethane resins, acrylic resin, phenol-formaldehyde resin, and combinations thereof.

4. The process described in claim 1 where the one or more curing agents is selected from the group Lewis acids, tertiary amines, mono ethanol amine, benzyl dimethylamine, 1,4-diaza-bicylo[2,2,2] octane, 1,8-diazabicylo[5,4,0] undec-7ene, cycloaliphatic amines, amidoamines, aliphatic amines, aromatic amines, isophorone, Isophorone diamine, polyamides, boron tri-fluoride derivatives, imidazoles, imidazolines, morpholines, mercaptans, piperidines, sulfide, hydrazides, amides, and combinations thereof.

5. The process described in claim 1 where the particles are sand.

6. The process described in claim 1 where the resin is bisphenol A diglycidyl ether.

Description

DETAILED DESCRIPTION

(1) The present invention of an aqueous emulsion particle consolidation system involves a surfactant(s) that has a cloud point at or lower than the reservoir temperature in a water-based fluid as external phase, polyfunctional resin and curing agent as the internal phase, together to form an aqueous emulsion particle consolidation system. The reaction time of the resin and curing agent is delayed until the emulsion is delivered to the treatment area and heated to the cloud point of the surfactant. When the surfactant reaches its cloud point it loses its emulsifying characteristic and releases the resin and curing agent to consolidate the sand, proppants or any other material need to be consolidated. The water serves as a spacer to maintain the permeability required for oil and gas production after treatment. Unlike most prior art related to the subject, post flash is not required for the present invention to remove the excess resin/curing agent in order to maintain the permeability of the treatment area.

(2) The composition of the present invention includes:

(3) a) One or more surfactants, present from about 0.05 to 10.0 weight percent of the total composition, preferably 0.02 to 2.0 weight percent and most preferably 0.01 to 1.0 weight percent, including but not limited to anionic surfactant, cationic surfactant, nonionic amphoteric surfactant, and the combinations of two or more surfactants that have cloud points below the down hole application temperature.

(4) b) One or more polyfunctional resins, present from about 10 to 30 weight percent of the total composition, including but not limited to, bis-phenol A diglycidyl ether, bis-phenol F diglycidyl ether, cyclol aliphatic epoxides, furfuryl based epoxies, glycidyl ethers, poly glycidyl ethers, resins derived from cashew nut oil, novalac resins, polyurethane resins, acrylic resin, phenol-formaldehyde resin, and other polyfunctional resins, and combinations thereof

(5) c) One or more curing agents, present from about 0.5 to about 10 weight percent of the entire composition, preferably 0.5 to 5.0 weight percent, most preferably 0.4 to 2.0 weight percent, depending on the molecular weight and type of the curing agent, including but not limited to, Lewis acids, tertiary amines, mono ethanol amine, benzyl dimethylamine, 1,4-diaza-bicylo[2,2,2]octane, 1,8-diazabicylo[5,4,0]undec-7ene, cycloaliphatic amines, amidoamines, aliphatic amines, aromatic amines, isophorone, Isophorone diamine, piperidines, polyamides, boron tri-fluoride derivatives, functional resins, imidazoles, imidazolines, morpholines, mercaptans, sulfide, hydrazides, amides and their derivatives, and combinations thereof.

(6) d) Aqueous solvent, from about 60 to about 90 weight percent of the entire composition, including but not limited to fresh water, brine, synthetic brine, sea water, produced brine.

(7) e) Optionally other additives, including but are not limited to, diluents, crosslinking agents, pH control agents, viscosity control agents, defoaming agents, fluid loss additives, corrosion inhibitors, biocides, that are generally used for purposes known to the art may be added.

(8) The amount of surfactant is determined by the concentration necessary to emulsify the resin and curing agent. The amount of curing agent is determined by the amount of resin used so that the resin is cured in the desired amount of time at the desired temperature.

(9) The process of the present invention includes preparing an aqueous emulsion particle consolidation composition containing: a. One or more surfactants having a cloud point at or below the reservoir temperature, b. One or more polyfunctional resins, c. One or more curing agents, d. An aqueous solvent.

(10) Mixing the surfactant(s) and curing agents(s) with the polyfunctional resin, slowly adding the aqueous solvent into the polyfunctional resin containing dissolved surfactant and curing agent to form a uniform water external emulsion, introducing the composition into a subterranean reservoir and, allowing sufficient time for the composition to cure. Alternatively the surfactant can be added to the polyfunctional resin and mixed well. The aqueous solvent is slowly added to forma water external emulsion. Then the curing agent is added and mixed well. The composition is then pumped into a subterranean reservoir and sufficient time is allowed for the composition to cure.

(11) Non-inclusive applications for the process include adding the composition to a fracturing process with proppant during or at the end of the fracturing treatment to prevent proppant flowback after the fracture treatment.

(12) Another non-inclusive application for the process involves adding the aqueous emulsion particle consolidation system to gravel packs near the wellbore to prevent undesired sand production.

EXAMPLE

(13) The example below is illustrative only. The present invention may be modified and practiced in different or equivalent ways apparent to those skilled in the art having the benefit of the teachings herein.

Example 1

(14) 0.1 gram of a nonionic surfactant having a cloud point of 58° C. and 1.0 gram of a curing agent are mixed with 10.0 grams Bisphenol A diglycidyl ether resin using a magnetic stirrer. After mixing for 2 minutes, 50 grams of Houston tap water are added slowly while stirring to form an homogeneous emulsion.

(15) One pore volume of the emulsion made above is injected to a 10-cc disposable syringe containing 7 grams of 20/40 sand. The tip of the syringe is then capped and it is set in a 90C oven for 24 hours.

(16) The syringe is removed from the oven and the resulting consolidated sand block is tested for regained permeability and unconfined crush strength (UCS) using the methods known to those familiar with the art. The sand block was found have a regained permeability of 93% and a UCS of 1275 lb/in.sup.2.

(17) Alternately it has been found that equivalent results are obtained if the curing agent(s) are added after forming the emulsion of the polyfunctional resin in the aqueous solvent containing surfactant.

(18) The present invention may be modified and practiced in different or equivalent ways apparent to those skilled in the art having the benefit of the teachings herein.