ACID SURFACTANT COMPOSITION

COMPOSITION D'ACIDE SURFACTIVE

English Abstract

Surface-active acidic composition for the treatment of bottom hole zone of
injection and producing wells to increase permeability and filtration
properties of the layer. To increase dissolving and washing of asphalt, gum,
paraffin and clay (AGPC) sediments (mud), special ingredients should be added
to the mixture of hydrochloric and hydrofluoric acids and non-ionic surfactant-
solvent, such as aromatic hydrocarbon solvent (e.g., toluene) or the mix of
halogen solvents. During the treatment of the well bottom hole zone such a way
influence of acids on clay plugs becomes more effective due to dissolving of
hydrophobic AGPC sediments. Presence of nonionic surfactant in this
composition, it might be hydroxyethylated alkyl phenol - A.PHI. 9-12) causes
better solubility and more uniform (steady) distribution of AGPG solvent in
the water-acidic composition as a stable low viscous micro-emulsion oil-in-
water type with high peptic and inhibiting properties.

French Abstract

Cette invention concerne une composition tensioactive acide que l'on utilise afin de traiter la zone de fond de puits dans des puits d'injection ou de production de manière à accroître les propriétés de perméabilité et de filtration de la couche. Afin d'accroître les propriétés de dissolution et de lavage sur les sédiments à base d'asphalte et de gomme, de paraffine et d'argile (boues), on ajoute des ingrédients spéciaux au mélange d'acides chlorhydrique et fluorhydrique et de tensioactif non ionique, à savoir un solvant qui peut consister en un solvant à base d'hydrocarbure aromatique comme du toluène, ou un mélange de solvants halogènes. Lors du traitement de la zone de fond de puits à l'aide de cette composition, la dissolution des sédiments hydrophobes à base d'asphalte et de gomme, de paraffine et d'argile permet d'accroître l'efficacité des acides sur les bouchons d'argile. La présence d'un tensioactif non ionique (par exemple du phénol d'alkyle hydroxyéthylé A.PHI. 9-12) permet d'améliorer la solubilité et d'obtenir une répartition uniforme du solvant d'asphalte et de gomme, de paraffine et d'argile dans la composition aqueuse et acide. Cette dernière consiste en une micro-émulsion stable, faiblement visqueuse et de type huile-eau qui possède des propriétés inhibitrices et de peptisation élevées.

Claims

HERE IS WHAT WE CLAIM:
1. Acid surfactant composition for bore hole treats of oil wells, including
the mixture of inhibited hydrochloric and hydrofluoric acids, non-ionogenic
surfactant
substance and water, that differs in the following, that in order to increase
the dissolving
and oil washing-out capabilities, the composition, additionally, in emulsified
condition.
contains the effective AWPS (asphalt-wax and paraffin sediments) solvent with
the
following ratio of the components (% mass):
~ Inhibited hydrochloric acid (calculated for HCI) -5.0 - 23.0
~ Hydrofluoric acid - 2.0 - 10.0
~ Non-inogenic surfactant substance -1.0 - 5.0
~ AWSP solvent -5.0 - 25.0
~ Water - the rest
2. Acid surfactant composition for bottom hole treatments of oil wells as per
Claim
# 1, that differs in the following; that as a AWSP solvent they use the
aromatic
hydrocarbon fraction (e.g. toluene- xylene fraction) or the mixture of gala-
derived
solvents (e.g. APK product, produced by "CHIMPROM" JSC as per
Spec.# TY 2122-199-05-76-34-68-94).

Description

CA 02286140 1999-07-29
ACID SURFACTANT COMPOSITION
The invention is referred to the oil production industry and can be applied to
treat the
near well bore area.
A composition is known for treatment of the near well bore area of the
reservoir which
contains a surfactant, for example, 0.25 - 3.0% of oil or synthetic sulphonate
and
hydrochloric acid with the concentration of 5-24% (USSR Patent Ns 1161699, E
21 B
43/22, 1984).
The disadvantage of the aforementioned composition is not high enough washing
properties for asphaltene-resin and paraffin deposits in the near well bore
area of the well
and insufficient decrease in water permeability of highly permeable zones of
heterogeneous reservoirs.
The closest to the proposed invention in its technical essence and achieved
results is
another composition for treatment of the near well bore area (USSR Patent l~
1571224, E
21 B 43/27, 1998).
The disadvantage of this method is insufficient ei~ectiveness of treatment of
the filtrates
in the near well bore area of highly flooded wells.
The objective of the invention is to raise the effectiveness of the near well
bore area
treatment of highly flooded wells through high washing and solvent properties
of the
applied composition.
The objective is attained due to the fact that unlike known compositions the
applied
composition that contains inhibited hydrochloric acid and hydrofluoric acid,
non ionic
surfactant and water, in addition contains emulsified aromatic or
haloderivative
hydrocarbon with the following ratio of components, % of mass, as a solvent of
asphaltene-resin and paraffin deposits (ARPD):
Inhibited hydrochloric acid (HCL) 5.0-23.0
Hydrofluoric acid 2.0-10.0
Non ionic surfactant 1.0-5.0
ARPD solvent 5.0-25.0
Water remaining portion
To prepare this acid surfactant composition we use: hydrochloric acid
(standard TU
4814-82); hydrofluoric acid (T'U 1426-84); oxiethylated alkyl phenol, for
example,
Neonol AF 9-12 brand as a non-ionic surfactant and as an ASPD solvent a
fiaction of
aromatic hydrocarbons or APK-product manufactured by '~Chimprom" (TU 2122-199-
05-76-34-68-94) which is a mixture of haloderivative compounds. The
composition is
prepared as follows: initially a calculated amount of non-ionic surfactant is
dissolved in
an aromatic or haloderivative solvent or a mixture of these solvents. Later
resulted

., CA 02286140 1999-07-29
surfactant solution is mixed with water that has a prior added estimated
amount of
hydrochloric acid and hydrofluoric acid.
Unlike known surfactant and acid compounds for treatment of the near well bore
area the
present composition which presents a well filtering in the porous media micro
emulsion
system, does not only clean the near well bore area from salts and drill mud
residue
deposits but also peptizes and dissolves paraffin, resin and asphaltene
deposits. Besides,
the composition preserves its high oil displacement properties after injection
into the
reservoir and after it is neutralized.
For comparative evaluation of effectiveness of the compositions we prepared
the
compounds according the invention and the prototype (AC J~ 1571224)
The presented composition is prepared according to the procedure described
above. The
prototype is prepared dissolving neonole and sulphanole one after another in
diluted
hydrochloric acid with ratios described in the invention formula.
A part of prepared acid surfactant compositions was analyzed for their
dissolving
properties as compared to an artificially blended mixture containing calcium
carbonate
(50% of mass), clay (20'/° of mass) and ARPD (30% of mass).
The dissolving ability (Pc) of the compositions was evaluated according to the
intensity
of the chemical reaction between them and calcium carbonate and the decrease
in the
residual weight of dissolved mixture after the chemical reaction ended based
on the
formula (1):
Pc = [(Go - Gk) x l oo] /Go,
Go: treated mixture weight, g.
Gk: undissolved residue after the mixture was treated, g.
Oil displacement ability of compared acid surfactant compositions was analyzed
after
they were neutralized by calcium carbonate on a reservoir model 50 cm long and
1.1 cm
in diameter made of silica sand with 36% porosity and 3.8 mkm2 water
permeability.
Initially the model was saturated with produced water with 12.7~/°
total salt content. Later
water was displaced by oil with 9.2 cSp viscosity at 20°C. Oil then was
displaced by the
same produced water to the maximum water cut in fluid samples coming from the
core.
Final displacement reached f>S-70%.
Thus treated cores were analyzed for effectiveness of residual oil washing by
compared
neLltral compositions through their injection in the amount of one pore volume
and later
displacement of the injected substance by produced water until oil stopped
being washed
out of the core. Tests were run at room temperature (20 t 5 °C).

.. CA 02286140 1999-07-29
Oil displacemem ability of compared compositions was evaluated by the volume
of
incremental oil produced from the core which was presented as a displacement
ratio NK
in volume percent of residual oil after flood.
Test results for the developed and available compositions are presented in
Table 1.
Based on the data provided in the Table the proposed composition unlike its
prototype
has a higher dissolving ability not only related to the calcium carbonate
salts deposits, but
at equal content of non-ionic surfactant (comparing compositions 2 and 5) it
has a 1.5
times better dissolving ability for ARPD. Oil washing properties of
composition 2 are 2
times higher that those of composition 5.
At higher HCL content (23% of mass) the proposed composition (composition 3)
in
comparison with the prototype (composition 6) has clearly determined
dissolving
properties towards clay particles (due to HF presence) and 100'/0 oil washing
properties
due to a higher content of non-ionic surfactant (5% of mass) and effectiveness
of APK
solvent (25% of mass). Compared prototype (composition 6) dissolves only 65%
of mass
of the artificially blended mixture even at a total content of ionic and non-
ionic
s<ufactaats of 5.3% of mass and HCL of 23 % of mass. This shows that the
dissolving
ability of this composition towards ARPD and clay components (allowing for
100% of
calcium carbonate dissolving) does not exceed 15% of their mass content.
Application: oil production. The composition can be used for treatment of the
near well
bore area of injection and production wells to increase permeability and
filtration
propeaties of the reservoir. The essence of the invention: modifying
dissolving and
washing properties of the composition towards asphaltene-resin, paraffin and
clay
deposits through adding into the mixture inhibited hydrochloric and
hydrofluoric acid and
non-ionic surfactant, an effective aromatic hydrocarbon solvent (toluene, for
instance) or
a blend of haloderivative solvents mamifact<u~d by '~Chlorprom" according to
standard
TU 2122-199-OS-76-34-68-94). While treating the near well bore area with the
described
composition as a result of ARPR (asphaltene-resin and paraffin residue)
dissolving more
effective chemical impact of the above acids on filtrate damaged areas of the
reservoir
takes place. Non-ionic surfactant (for example, neonole AF 9-12) present in
the
composition provides equal distribution of the ARPR solvent in water and acid
composition due to the solubility effect. The solvem is distributed as a
stable low
viscosity micro emulsion oil in water type with high peptizing and inhibiting
properties.

CA 02286140 1999-07-29
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