Title of Invention

SYSTEM FOR TREATING AN UNDERGROUND FORMATION

Abstract A method of treating an underground formation of an oil reservoir, comprising the sequential steps of (a) contacting the formation with an aqueous medium, (b) contacting the underground formation with a hydrocarbon fluid, (c) contacting the underground formation with a solvent in the form of a glycol ether, (d) contacting the underground formation with a first consolidation constituent solution, mainly comprising a poly epoxy resin, (e) contacting the underground formation with second consolidation constituent substantially homogenous solution mainly comprising a curing agent in a solvent.
Full Text SYSTEM FOR TREATING AN UNDERGROUND FORMATION
The present invention relates to a method of treating an underground formation. More in particular, the present invention relates to a method of treating an underground formation in oil and gas reservoirs, by using a consolidation solution of an epoxy resin and a curing agent. Such a method was known from e.g. EP 0864032 Bl, which actually disclosed a method of treating an underground formation comprising the sequential steps of
(a) contacting the formation with an aqueous medium;
(b) contacting the formation with a hydrocarbon fluid;
(c) contacting the formation with a solvent in the form of a glycol ether;
(d) contacting the formation with a consolidation solution comprising a monomeric diglycidyl ether of bisphenol A, such as EPDCOTE 828, in a proportion of from 30 to 60 %m and methylene dianiline as curing agent in a proportion of from 5 to 20 %m in the solvent and
(e) contacting the formation with a viscosified hydrocarbon fluid (the so called over-flush) to displace a majority of the resin phase and to restore the permeability of the treated underground.
As suitable glycol ethers for the solvent were exemplified methoxy propanol, butoxyethanol, hexoxy ethanol and isomers of these glycol ethers, which may be optionally mixed with a minor amount (e.g. less than 10 %m) of a polyethylene glycol, having an average molecular mass of around 400, to adjust the viscosity.
It is true that on the other hand was known from * Journal of Petroleum Technology', December 1966, B.R. Treadway, H. Brandt and P. Harold Parker, page 1537-1543, a three step sand consolidation process. Said process consisted of
(1) injecting epoxy resin
(2) following the displacement of the resin by diesel oil to establish formation permeability, and
(3) activating the resin to consolidate the formation by injecting an activator flush to cure the epoxy resin.
The applied epoxy resin system consisted of pure epoxy resin or an epoxy resin acid anhydride system.

Moreover it was known from '52nd Annual Fall Technical Conference and Exhibition of the Society of
Petroleum Engineers of A3ME', Denver, Colorado, Oct 9-12, 1977, W.L. Penberthy, CM. Shaugnessy,
C. Gruesbeck and W.M. Salathiel (Exxon Production Research Co.), that for effective sand
consolidation, the epoxy resin must wet the surface of the sand grains and that in those cases where the
resins lack this ability a pre-flush which preferentially removes water in the presence of oil is essential
and particularly when there had been a prior mud acid treatment. Radial field-scale model studies had
demonstrated that pre-flush effectiveness was dependent on pre-flush volume, viscosity and sand
permeability.
Due to the increased economic requirements for present exploitation of oil reservoirs, in incompetent,
high temperature, high pressure formations said underground treating has to be further improved. By the
term incompetent one will understand: formations of insufficient mechanical strength to allow sand-free
production.
It will be appreciated that a clear disadvantage of the prior art underground treating methods was that
the actual curing of the supplied epoxy resin and curing agent did not take place at the desired places
due to high temperatures in the underground to be treated and/or the insufficient solubility or
dispersability of the applied curing agents in the glycol ether solvent system or due to an unsuitable
viscosity of the consolidation solution which caused that the required stoichiometric mutual ratio
between epoxy resin molecules and curing agent molecules, could not be reached on the spot or in the
specific area to be treated.
It will be appreciated that more in particular, consolidated formations should have the strength to
withstand stresses induced by adjacent rock strata and stresses imposed by the flow of fluids into the
wellbore. This consolidation strength should be maintained under production conditions, moreover the
consolidated formation should have sufficient permeability to permit unobstructed flow of fluids into
the wellbore and must show sufficient resistance to the conditions of well stimulation dilute solutions of
acids, such as hydrochloric acid, hydrofluoric acid and acetic acid.
An object of the present invention is therefore to provide an improved method of treating hydrocarbon
reservoirs in order to eliminate the entrainment of sand minerals and as a consequence wear of
production equipment.
As result of extensive research and experimentation, such improved treating method has been
surprisingly found.

Accordingly, the invention relates to a method of treating an underground formation of an oil reservoir in incompetent, high temperature, high pressure formations, comprising the sequential steps of
a) contacting the formation with an aqueous medium,
b) contacting the underground formation with a hydrocarbon fluid,
c) contacting the underground formation with a solvent in the form of a glycol ether,
d) contacting the underground formation with a first consolidation constituent solution, mainly
comprising a poly epoxy resin derived from bisphenols, or a poly phenolic resin (novolac
resins), in a solvent mainly comprising a glycol ether, in an epoxy resin concentration of
from 25 to 75%m and having a viscosity in the range of from 10 to 100 m Pa.s ,
c) contacting the underground formation with a second constituent substantially homogenous
consolidation solution mainly comprising a curing agent in a solvent, mainly comprising a hydrocarbon fluid. Said curing agent occurring in a concentration in the range of from 0.5 to 20 %m, and the solution having a viscosity such, that the ratio between the viscosity of the solution in step (d) and of the solution in step (e) is in the range of from 1.0 to 5. With the term 'mainly comprising' as used throughout the present specification is meant that the specified constituent (i.e. epoxy resin or solvent) is the sole component or can be mixed with minor amounts of co-components i.e. in amounts of 10 %m or less and preferably in amounts of 5 %m or less. For example, the preferably applied poly epoxy resin is a poly epoxy novolac resin, which optionally can be mixed with up to 10 %m of a diglycidylether of diphenylolpropane (bisphenol A), or of diphenylolmethane (bisphenol F).
The applied poly epoxy resin may be derived from phenol, cresols, xylenols, carvacol, cumenol and phenols, substituted with halogen or lower alkyl, having from 1 to 4 C atoms.
More preferably a poly epoxy phenol or cresol novolac resin is used of the type which is commercially available as EPIKOTE 154 (Traded by Resolution Performance Products). The aqueous medium used in step (a) can be naturally occurring, treated i.e. filtered or desalinated water, such as pretreated sea water or water from rivers, or a KC1 or NaCl brine, containing up to 6 %m of KC1 or NaCl, Na2S04, K2S04, NaN03, KN03 and the like and preferably up to 3 %rn and more preferably the same brine as originally occurring in the underground involved. The hydrocarbon fluid, used in step (b) can be in principle selected from a great variety of hydrocarbons but will be preferably selected from aliphatic hydrocarbons and more preferably gasoils .

The glycol ether solvent to be used in steps (c) and (d) can be selected from ethers of a C2 to C6
dihydric alkanol, containing at least one Ci to C6 alkyl group.
Preferably mono ethers of dihydric alkanols, more preferably glycol ethers selected from the group
including methoxypropanol, butoxyethanol, hexoxyethanol and the isomers of these glycol ethers, or
mixtures thereof.
To adjust the viscosity of said solvent it may further contain a minor amount e.g. less than 10 %m, of a
polyethylene glycol or polyvinyl pyrrolidone, having an average molecular mass of about 400.
The curing agent to be used in the solution of step (e) can be selected from a great variety of usually
applied curing agents for epoxy resins with the restriction that such curing agent must be completely
miscible in the applied hydrocarbon fluid in a sufficient degree in order to reach the required
concentrations, that the curing agent does not produce low molecular byproducts during curing and that
the finally cured epoxy resin on the spot has sufficient mechanical strength, i.e. between the individual
mineral groups on almost only on contact areas and must show a minimal impediment to fluid flow at
the curing conditions on the spots to be treated, i.e. high temperature (from 80 to 200°C) and high
pressure (from 10 to 100 atm).
Preferably amine type curing agents will be used selected from aliphatic di or poly amines or alkylaryl
amines, more preferably diethylene toluene diamine, diethylene xylene diamine, diethylene dianiline are
used, of which diethylene toluene diamine is the most preferred.
The solvent to be used in the step (e) is a hydrocarbon mixture e.g. SHELLSOL D70, SHELLSOL
TD, SHELLSOL D40, SHELLSOL LF (SHELLSOL is a Shell Trade mark ), EXXSOL D70 EXXSOL
155/170, EXXSOL D220/230 (EXXSOL is a Exxon Mobil Trade mark ) HYDRSOL 75/95 N,
HYDROSOL 100/130 N (HYDROSOL is a Total Fina Trade mark). To ensure that the viscosity of the
mixture in step (e) has a viscosity in excess of that used in step (d), a viscosifier may be used, for
example lubricant oil such as VALVATA 460, SHELLVIS 50 (VALVATA & SHELLVIS are Shell
Trade mark), Worm Gear Oil (Amoco Oil Co), CYLESSTIC TK-460 (CYLESSTIC is a Exxon Mobil
Trade mark) SENATE 460 SENAT is a Gulf Oil Co Trade mark).
It will be appreciated that a catalyst has preferably to be applied for the efficient curing of the epoxy
resin/curing agent on the spot to be treated. Suitable curing catalysts can be selected from salicylic acid
and phosphine, phosphonium amine and ammonium catalysts, which are generally known in the art.

Said catalyst can be added in amounts of up to l%m relative to the weight of the total supplied solution
either in step (d), i.e. premixed with the epoxy resin component, or can be added in step, i.e. premixed
with the curing agent in a solvent, of which the latter embodiment is preferred.
It will be appreciated that such sand consolidation method could meet all the presently desired sand
consolidation characteristics, as were specified herein before.
The invention is further illustrated by the following examples, however without restricting its scope to
these embodiments.
Examples To illustrate the effect of method of the present on the unconfined compression strength, several samples were made and subjected to treatments. For each test three samples were made of "METTET QUARTZ SAND" (96% of the grain diameters are in the range of from 63 to 180 urn and D50 -130 urn) in a glass tube, each sample had a diameter of 3.5 cm and a length of 17 cm. After the sand had been placed in the tube the porosity, 3> (in %)was determined. The sand pack was flushed with butane to remove air, and thereafter the sand pack was flushed with an aliphatic hydrocarbon in which butane dissolves to remove the butane. The initial permeability, K{ (in Darcy), was determined.
To simulate formation conditions, the following fluids were injected (1) methoxypropanol, (2) brine (2%m KC1); and (3) about 10 pore volumes of crude oil to establish irreducible water saturation.
The treatment according to the invention comprises contacting the samples filled with crude oil at irreducible water saturation in the following sequence: (a) contacting the sample with 2 pore volumes of a 2%m KC1 brine; (b) contacting the sample with 2 pore volumes of gasoil: (c)contacting the sample with 2 pore volumes of methoxypropanol; (d) contacting the sample with 1 pore volume of a consolidation solution of
Example A: 1 pore volume (pv) of 28.8%m:m EPIKOTE 154 in methoxypropanol, followed by 4 pv of
3.7%m:m DETDA in a hydrocarbon solution, consisting of 31.7% mm SHELLSOL D70 and 68.3%
m:mVALVATA460.
Example B: 1 pore volume (pv) of 62.0%m:m EPIKOTE 828 in methoxypropanol, followed by 4 pv of
1.96%m:m DETDA in a hydrocarbon solution, consisting of 31.7% mm SHELLSOL D70 and 68.3%
m:mVALVATA460.

Example C: 1 pore volume (pv) of 38.0%m:m EPIKOTE 154 in methoxypropanol, followed by 4 pv of
7.2%m:m DETDA in a hydrocarbon solution, consisting of 33.1% m:m SHELLSOL D70 and 66.9.3%
m:mVALVATA460.
Example D: 1 pore volume (pv) of 38.0 %m:m EPIKOTE 154 in methoxypropanol, followed by 4 pv of
21.6%m:m DETDA in a hydrocarbon solution, consisting of 36.0% m:m SHELLSOL D70 and 64.0%
m:mVALVATA460.
Comparative Example : 1 pore volume (pv) of 46.5%m:m EPIKOTE 828 and 13.5% MDA m:m in
methoxypropanol, followed by 4 pv of a hydrocarbon solution, consisting of 31.7% m:m SHELLSOL
D70 and 68.3%m:m VALVATA460
After the treatment the final permeability, K c (in Darcy), and the unconfined compression strength,
UCS (in bar), were determined. The results are summarized in Table 1 below.
O, in % K i , in Darcy K e, in Darcy UCS, in bar
Example A 40 4.54 4.51 180
Example B 40.4 4.34 4.30 106
Example C 40.5 4.44 4.15 157
Example D 40.4 4.73 4.28 73
Comparative 41.2 4.13 3.96 156
Table : 1 Results of the treatment From the examples made according the present invention one can appreciate that the Example treated according to the inventions has a higher permeability for an excellent to acceptable unconfined compression strength compared to the state of the art technology. Moreover it has been found that the drop of permeability for the sample treated according to the invention is lower than the one reported in the prior art.



CLAIMS
1. A method of treating an underground formation of an oil reservoir, comprising the sequential steps of
a) contacting the formation with an aqueous medium,
b) contacting the underground formation with a hydrocarbon fluid,
c) contacting the underground formation with a solvent in the form of a glycol ether,
d) contacting the underground formation with a first consolidation constituent solution, mainly comprising a poly epoxy resin derived from bisphenols, or a poly phenolic resin (novolac resins), in a solvent mainly comprising a glycol ether, in an epoxy resin concentration of from 25 to 75%m and having a viscosity in the range of from 10 to 100 mPa.s.
e) contacting the underground formation with second consolidation constituent
substantially homogenous solution mainly comprising a curing agent in a solvent, mainly
comprising a hydrocarbon fluid. Said curing agent occurring in a concentration in the range of
from 0.5 to 20 %m, and the solution having a viscosity such, that the ratio between the viscosity
of the solution in step (d) and of the solution in step (e) is in the range of from 1.0 to 5.
2. Method according to claim 1, wherein the epoxy resin solution is selected from a solid or liquid (at 23 deg C) epoxy-novolac resin and more preferably a solid epoxy novolac resin.
3. Method according to claim 1, wherein the curing agent is selected from aliphatic polyamines, alkyl-aryl polyamines and more preferably diethylene toluene diamine (DETDA)

4. A method of treating an underground formation of an oil reservoir substantially as herein described and exemplified.


Documents:

2584-CHENP-2004 AMENDED CLAIMS 09-06-2010.pdf

2584-CHENP-2004 AMENDED PAGES OF SPECIFICATION 09-06-2010.pdf

2584-CHENP-2004 CORRESPONDENCE OTHERS 09-06-2010.pdf

2584-chenp-2004 form-3 09-06-2010.pdf

2584-CHENP-2004 OTHER PATENT DOCUMENT 09-06-2010.pdf

2584-CHENP-2004 POWER OF ATTORNEY 09-06-2010.pdf

2584-CHENP-2004 CORRESPONDENCE-OTHERS 03-11-2009.pdf

2584-CHENP-2004 PCT SEARCH REPORT 03-11-2009.pdf

2584-chenp-2004-abstract.pdf

2584-chenp-2004-claims.pdf

2584-chenp-2004-correspondnece-others.pdf

2584-chenp-2004-correspondnece-po.pdf

2584-chenp-2004-description(complete).pdf

2584-chenp-2004-form 1.pdf

2584-chenp-2004-form 3.pdf

2584-chenp-2004-form 5.pdf

2584-chenp-2004-pct.pdf


Patent Number 243427
Indian Patent Application Number 2584/CHENP/2004
PG Journal Number 43/2010
Publication Date 22-Oct-2010
Grant Date 18-Oct-2010
Date of Filing 17-Nov-2004
Name of Patentee RESOLUTION RESEARCH NEDERLAND B.V.
Applicant Address Vondelingenweg 601, NL-3196 KK Vondelingenplaat Rotterdam (NL)
Inventors:
# Inventor's Name Inventor's Address
1 BOSSAERTS, Jan, Dirk Poenaardlaan 23, B-3090 Overijse
2 RANS, Marc, Jozef Bovenbosstraat 51, B-3053 Haasrode
PCT International Classification Number E21B 43/02
PCT International Application Number PCT/EP2003/004458
PCT International Filing date 2003-04-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 02076950.1 2002-05-17 EUROPEAN UNION