CN104632151A - Method for improving recovery efficiency by ion matching water drive - Google Patents

Abstract

The invention provides a method for improving recovery efficiency by ion matching water drive. The method comprises the steps of detection of a target low-permeability sandstone oil pool, selection of ion matching water, core fluidity test and the like. The method uses the low-permeability sandstone oil pool as an object, uses the deepening of ion matching water drive-oil/water/rock microcosmic action mechanism as a target, overcomes an ion matching water drive pressure reduction and injection increment technology, breaks through the bottleneck of a technology for improving the recovery efficiency by low-permeability oil pool, builds a technology for improving the recovery efficiency by the low-permeability sandstone oil pool with ion matching water as a carrier, and forms a technology for improving oil displacement efficiency by ion matching water drive with proprietary intellectual property rights.

Description

A kind of ion coupling water drive improves the method for recovery ratio

Technical field

The present invention relates to the method that a kind of ion coupling water drive improves recovery ratio, belong to technical field of petroleum extraction.

Background technology

Oil-field flooding is supplementary stratum energy, and setting up one of most simple effective method of displacement pressure system, be also the agent technology that is produced from most of oil field, and water drive will be the agent technology of global oil field development within considerable time.The importance of low permeability and ultra-low permeability reservoirs exploitation is consisted of reserves, the analysis of contribution to yield is apparent.Along with the continuous intensification of Exploitation degree, the exploitation of the economical and effective of low-permeability oilfield be still faced with production decline and realize recovery ratio, productivity index declines with extract steady oily, set up the multiple challenge such as moisture of effective pressure displacement system and control.Be different from middle and high infiltration oil reservoir, the raising recovery efficiency techniques such as chemical flooding, mixed phase drive, air drives are subject to the impact of the factor such as reservoir condition, material source in the application of low-permeability oil deposit, still do not make substantial breakthroughs.

Study fine flowing environment current downflow medium and reservoir interacts and seepage flow mechanism problem has directive significance to solving LOW PERMEABILITY RESERVOIR development problem.The key issue faced discloses the interaction mechanism in injected media-crude oil-formation water-reservoir, and research and development are by playing the effect utilizing the interaction mechanism of reservoir-fluid to improve the water drive that becomes more meticulous.External emphasis direction in water drive becomes more meticulous is low mineralization water drive, as far back as Tang G.Q. and Morrow (Tang and Morrow1999a in 1996; Tang and Morrow1996; Tang and Morrow1997; Tang and Morrow1999b) report low mineralization effect in rock core displacement test the earliest, the oil displacement efficiency proposing dilution formation water is higher than the oil displacement efficiency of prime stratum water.

After this large quantity research has been carried out for high salinity reservoir, seawater injection oil reservoir etc. abroad, for low mineralization effect proposes multiple mechanism explain, over nearly 3 years, low mineralization water drive has become the study hotspot of academia, and the Quantity of Papers relating to low mineralization water drive in the paper of the international conferences such as annual SPE, SCA, EOR exponentially rises.International major oil companies and institution of higher learning have dropped into a large amount of research effort in low mineralization water drive, and have carried out field trial in oil fields such as Syria, Alaska north slopes.LoSal technology (low mineralization the water drive) (BP2011 that BP proposes; Jerauld, et al.2008; Lager, et al.2008; Shiran and Skauge2012), its essence such as DWF technology (design water drive) of proposing of Shell is all low mineralization water drive.

But, for the water drive effect of water extraction high recovery rate for low permeability sandstone reservoir, also there is no suitable evaluation method at present.

Summary of the invention

For solving the problems of the technologies described above, the object of the present invention is to provide a kind of ion to mate the method for water drive raising recovery ratio, carrying out displacement of reservoir oil operation by adopting ion coupling water and changing the discrete power in interface, thus improving the recovery ratio of oil reservoir.

For achieving the above object, the invention provides the method that a kind of ion coupling water drive improves recovery ratio, it comprises the following steps:

The detection of target low permeability sandstone reservoir:

According to ionic type and the intensity of the formation water of target low permeability sandstone reservoir, formula (1) is adopted to calculate the Debye constant of formation water:

$\mathrm{\κ}={(\underset{i}{\mathrm{\Σ}}{\mathrm{\ρ}}_{\∞i}{e}^2{Z}_i^2/{\mathrm{\ϵ}}_0\mathrm{\ϵkT})}^{1/2}---\left(1\right)$

In formula (1): k is Boltzmann constant, T is the absolute temperature of water, ε ₀for absolute dielectric constant, ε is medium relative dielectric constant, and i represents the ion in water; ρ _{∞ i}for ion concentration, unit is mol/L; Z _ifor the chemical valence of ion i; ε is medium relative dielectric constant, refers to the dielectric constant relative to vacuum medium, also with regard to relative medium absolute dielectric constant;

Measure the Hamaker constant of the oil/water/rock of target low permeability sandstone reservoir, employing formula (2), (3) calculate Van der Waals force Π corresponding to formation water _{van-der-Woals}:

${\mathrm{\Π}}_{\mathrm{Van}-\mathrm{der}-\mathrm{Waals}}\left(h\right)=\frac{-A(15.96h\left(x\right)/\mathrm{\λ}+2)}{12\mathrm{\πh}{\left(x\right)}^3{(1+5.32h\left(x\right)/\mathrm{\λ})}^2}---\left(2\right)$

In formula (2), A is Hamaker constant; λ is London wavelength, and unit is nm; H (x) is the distance (also can be described as water film thickness distribution) between oil/water and water/rock interface, and unit is nm;

Measure the oil/water of target low permeability sandstone reservoir and the Zeta potential of water/rock interface, employing formula (3), (4) calculate double electrode layer repulsion Π corresponding to formation water _electrical:

${\mathrm{\Π}}_{\mathrm{electrical}}\left(h\right)=n_b{k}_{B}T\left(\frac{2{\mathrm{\ψ}}_{r1}\left(x\right){\mathrm{\ψ}}_{r2}\left(x\right)\cosh \left(\mathrm{\κh}\left(x\right)\right)-{\mathrm{\ψ}}_{r1}^2\left(x\right)-{\mathrm{\ψ}}_{r2}^2\left(x\right)}{{\left(\sinh \left(\mathrm{\κh}\left(x\right)\right)\right)}^2}\right)---\left(3\right);$

ψ _x=ψ ₀e ^-κh(x)(4)

In formula (3), (4): r1, r2 represent the interface of oil/water, water/rock respectively; ψ _r1, ψ _r2be respectively oil/water, water/rock interface in the Zeta potential value of x direction (range directions namely between two interfaces), calculated by formula (4); ψ ₀for oil/water, the Zeta potential value of water/rock interface in x=0 position, directly test draws; k _bfor bohr grows rigorously constant; ψ _r1for the Zeta potential at oil/water interface, unit is mV; ψ _r2for the Zeta potential of water/rock interface, unit is mV; κ is Debye length, and unit is m ^-1; A _kfor proportionality constant; E is elementary charge, and unit is C; n _bfor the ion number density (this solution refers to the aqueous systems of different ions type and concentration, refers to prime stratum water and ion coupling water in the present invention) in solution;

Structural capacity Π corresponding to formation water is calculated in conjunction with Dybye constant and formula (5) _structure:

${\mathrm{\Π}}_{\mathrm{structure}}=A_k\exp (-\frac{h\left(x\right)}{h_s})---\left(5\right);$

Wherein, h (x) is water film thickness distribution, and unit is nm; h _sfor Debye length characteristic;

Micro force Π between the rock/Shui Heshui/crude oil interface calculating target low permeability sandstone reservoir according to formula (6) _total, the Π that namely formation water is corresponding _total, and obtain Π corresponding to formation water _totalrelation curve along with interface distance change:

Π _Total=Π _structure+Π _electrical+Π _{Van-der-Woals}(6)；

If the Π that formation water is corresponding _totalall be greater than 0, and the Π that formation water is corresponding _totalrelation curve entirety along with interface distance change presents the trend of monotone decreasing, and so this target low permeability sandstone reservoir need not adopt ion coupling water to carry out water drive operation; If the Π that formation water is corresponding _totaland inequality is greater than 0 or Π corresponding to formation water _totalalong with a part for the relation curve of interface distance change presents monotonically increasing trend, then ion coupling water is adopted to carry out water drive operation to this target low permeability sandstone reservoir;

The selection of ion coupling water:

According to the salinity Selective ion mode coupling water of the formation water of target low permeability sandstone reservoir, according to ionic type and the intensity of this ion coupling water, formula (1) is adopted to calculate the Debye constant of ion coupling water;

Measure the Hamaker constant of the oil/water/rock between the crude oil of ion coupling water and target low permeability sandstone reservoir, rock, adopt formula (2) to calculate Van der Waals force Π corresponding to ion coupling water _{van-der-Woals};

Measure the oil/water between the crude oil of ion coupling water and target low permeability sandstone reservoir, rock and water/rock interface Zeta potential, employing formula (3), (4) calculate double electrode layer repulsion Π corresponding to ion coupling water _electrical;

Structural capacity Π corresponding to ion coupling water is calculated in conjunction with Dybye constant and formula (5) _structure;

According to the micro force Π between rock/Shui Heshui/crude oil interface that formula (6) calculates between ion coupling water and the crude oil of target low permeability sandstone reservoir, rock _total, the Π that namely ion coupling water is corresponding _total, and obtain Π corresponding to ion coupling water _totalalong with the relation curve of interface distance change;

If the Π that ion coupling water is corresponding _totalall be greater than 0, and the Π that ion coupling water is corresponding _totalrelation curve entirety along with interface distance change presents the trend of monotone decreasing, so carries out rock core fluidity test; If the Π that ion coupling water is corresponding _totaland inequality is greater than 0 or Π corresponding to ion coupling water _totalalong with a part for the relation curve of interface distance change presents monotonically increasing trend, then adjust the composition of ion coupling water, reduce salinity, improve the content of dianion, recalculate the Π that ion coupling water is corresponding _total, and obtain Π corresponding to new ion coupling water _totalalong with the relation curve of interface distance change, until the Π that ion coupling water is corresponding _totalall be greater than 0, and the Π that ion coupling water is corresponding _totalrelation curve entirety along with interface distance change presents the trend of monotone decreasing;

Rock core fluidity test:

Utilize rock core formation water and ion coupling water to carry out rock core fluidity test, obtain recovery ratio and the relation curve injecting PV number;

If the recovery ratio that ion coupling water is corresponding is all greater than recovery ratio corresponding to formation water, then determines that this ion coupling water is applicable to this target low permeability sandstone reservoir, and carry out water drive operation;

If the recovery ratio that ion coupling water is corresponding is not all greater than recovery ratio corresponding to formation water, then determine that this ion coupling water is not suitable for this target low permeability sandstone reservoir, the composition of adjustment ion coupling water, reduce salinity, improve the content of dianion, re-start and calculate Π corresponding to ion coupling water _total, obtain Π corresponding to new ion coupling water _totalalong with relation curve and the rock core fluidity test of interface distance change, until the recovery ratio that ion mates water corresponding is all greater than recovery ratio corresponding to formation water, carry out water drive operation afterwards.

At said method, preferably, described λ=1.00E+02nm, k _b=1.38E-23JK ^-1, T=2.98E+02K, hs=5.00E-02nm, e=1.602E-19C, ε ₀=8.85 × 10 ^-12farad/rice.

At said method, preferably, the relative dielectric constant of water is 78.36, and the relative dielectric constant of oil is 7.3, and the relative dielectric constant of rock is 8.0.

At said method, preferably, the value of h (x) is 0.4-20mm, is more preferably 0.5-20mm.

At said method, ion coupling water refers to the water containing appropriate ion and concrete suitably salinity or claims the aqueous solution, the preferred dianion of above-mentioned ion, such as calcium ion and magnesium ion etc., the salinity of ion coupling water is general otherwise lower than the critical water-sensitive salinity of target low permeability sandstone reservoir, preferably, the salinity of ion coupling water is not less than the critical water-sensitive salinity of target low permeability sandstone reservoir.

At said method, usually, ion coupling water should contain Ca in formation water in the oil reservoir that is suitable for ²⁺and Mg ²⁺, the salinity of formation water is not less than 10000mg/L, Ca ²⁺and Mg ²⁺content sum be not less than 100mg/L.These two conditions just as ion coupling water adaptive oil reservoir primary election condition, do not have very strict restriction.

At said method, when Selective ion mode coupling water, can obtain by adding inorganic salts in water, the ion adopted and inorganic salts can be common, and such as: calcium ion, magnesium ion etc., inorganic salts can be sulfate, hydrochloride etc., to this, can carry out as required selecting and adjusting, preferably, containing Ca in the ion coupling water adopted ²⁺and Mg ²⁺.More preferably, with the stereometer of ion coupling water, the composition of this ion coupling water comprises: K ⁺+ Na ⁺content be 1900mg/L, Ca ²⁺content be 200mg/L, Mg ²⁺content be 30mg/L, HCO ₃ ^-content be 30mg/L, Cl ^-content be 3199mg/L, SO ₄ ^2-content be 210mg/L, salinity is 5569mg/L.

First the method that ion provided by the present invention coupling water drive improves recovery ratio is evaluated the need of carrying out ion coupling water drive target low permeability sandstone reservoir, and this evaluation, by carrying out the detection of various parameter and calculating, obtains the Π that formation water is corresponding _totaland the Π that formation water is corresponding _totalalong with the relation curve of interface distance change, then according to Π _totalvalue and the trend of above-mentioned relation curve carry out; After determining that this target low permeability sandstone reservoir is applicable to carrying out ion coupling water drive, select suitable ion coupling water, then repeat parameter detecting above and computational process, obtain the Π that ion coupling water is corresponding _totaland the Π that ion coupling water is corresponding _totalalong with the relation curve of interface distance change, then according to Π _totalvalue and this ion of Trend judgement coupling water of above-mentioned relation curve whether be applicable to this target low permeability sandstone reservoir, if be applicable to, then carry out rock core fluidity test, if be not suitable for, then adjust composition and the salinity (generally will reduce salinity, improve the content of dianion) of ion coupling water, repeat above-mentioned judgement, until meet the demands; Recovery ratio and the relation curve injecting PV number is obtained by rock core fluidity test, again judge whether ion coupling water is applicable to this oil reservoir according to this curve, if be applicable to, carry out water drive operation, if be not suitable for, then adjust composition and the salinity of ion coupling water, repeat evaluation above, until meet the demands.In above process, relevant detection is all detections conventional in oil field, can carry out with reference to corresponding standard and Normal practice.The process of rock core fluidity test also can be carried out in a conventional manner.

In the present invention, if without specified otherwise or definition, definition and the computational methods thereof of all parameter code names and computational methods thereof and petrochemical industry are consistent, and those skilled in the art can determine that it measures and/or computational methods.

Existing water driving technology mainly supplements stratum energy, sets up displacement pressure system, is cemented out by crude oil by water filling.Mainly there is high, the super fracture pressure of water injection pressure or along problems such as the invalid water breakthrough problem after crack water injection and low permeability reservoir mineral sensitiveness in the exploitation of low-permeability oil deposit conventional waterflooding, these problems cause low permeability reservoir injury serious and irreversible, effective difficult water injection.In addition because the effective pore throat of LOW PERMEABILITY RESERVOIR is narrow and small, specific area is large, and cause capillary force large, the impact of liquid/liquid interface, liquid/liquid/solid interface effect is much larger than middle and high infiltration oil reservoir.In fine pore throat space, between flow media and reservoir, there is complicated interaction by physical absorption/desorption, fine migration, clay swell etc., great on the impact of water drive.Therefore, need the new concept setting up water injection in low-permeability oilfield, inject the medium that water is not merely makeup energy, the more important thing is the interaction playing and inject water and reservoir.The Van der Waals force, double electrode layer repulsion and the structural capacity that change oil/water/rock interface is mated by ion, thus the crude oil making to be adsorbed on rock wall can desorption automatically, reduce residual oil saturation, improve water-oil phase Gong Shen district, improve the oil displacement efficiency of water drive.

The present invention take low permeability sandstone reservoir as object, to deepen ion coupling water drive-oil/water/rock microcosmic effect mechanism for target, capture ion coupling water drive increasing injection technology, break through low Permeability reservoir for improving recovery factor technical bottleneck, set up and mate with ion the low permeability sandstone reservoir raising recovery efficiency technique that water is carrier, form the ion coupling water drive with independent intellectual property right and improve oil displacement efficiency technology.

Deybe constant, test oil/water termination Zeta potential and water/rock interface Zeta potential is calculated by test profit rock Hamaker constant, analysis stratum water ion composition by method provided by the invention, calculate the usable condition of the auxiliary judgment ion coupling water such as the Zeta potential regularity of distribution, Van der Waals force, double electrode layer repulsion and structural capacity, the operation of ion coupling water drive can be realized better.

Accompanying drawing explanation

Fig. 1 is that interfacial interaction power is with water film thickness variation relation curve.

Fig. 2 is different water type rock core displacement test recovery ratio and displacement PV number relation curve.

Detailed description of the invention

In order to there be understanding clearly to technical characteristic of the present invention, object and beneficial effect, existing following detailed description is carried out to technical scheme of the present invention, but can not be interpreted as to of the present invention can the restriction of practical range.

Embodiment

Present embodiments provide the method that a kind of ion coupling water drive improves recovery ratio, wherein, crude oil used is the degassed crude of long celebrating Xi137Jing, and the viscosity under 65 DEG C of conditions is 9.0mPas, and rock core adopts the reservoir cores of Xi137Jing, and temperature is 65 DEG C.Rock core ensaying the results are shown in Table 1, and experimental result shows, the reservoir cores clay mineral content of Xi137Jing is higher, and based on chlorite and kaolinite.Test oil component analysis result used in table 2, mainly based on saturated hydrocarbons, but have a small amount of non-hydrocarbon and asphaltene.The composition analysis result of prime stratum water and ion coupling water is in table 3, and the overall salinity of ion coupling water is relatively low, but is the increase in a small amount of dianion.Table 4 is the Zeta potential test result at prime stratum water and ion coupling aqueous systems and reservoir rocks and in-place oil interface, can find out that the Zeta potential of ion coupling water and reservoir rocks and in-place oil is far above formation water from test result.The rock core displacement test of different aqueous systems the results are shown in Table 5, and experimental result shows that ion coupling waterflood recovery efficiency factor is far above prime stratum waterflood recovery efficiency factor, and this technical scheme of mating water drive system with the ion of this invention is consistent.

Concrete evaluation procedure is as follows:

(1) according to ionic type and the Strength co-mputation Debye constant of formation water; Wherein, the ion set prejudice table 3 of formation water, adopts formula (1) to calculate; The Debye constant of the prime stratum water adopting formula (1) to calculate is 3.23nm ^-1.

(2) measure the Hamaker constant of oil/water/rock, wherein, the Hamaker constant of crude oil/formation water/rock is 8.14 × 10 ^-21, adopt formula (2) to calculate Van der Waals force corresponding to formation water, result is as shown in table 6.

(3) measure the Zeta potential of oil/water and water/rock interface, it is as shown in the table for result, and adopt formula (3) and formula (4) to calculate double electrode layer repulsion corresponding to formation water, result is as shown in table 6.

(4) calculate structural capacity corresponding to formation water in conjunction with the calculating of Dybye constant and formula (5), result is as shown in table 6.

(5) the micro force Π between rock/Shui Heshui/crude oil interface is calculated according to formula (6) _total(the Π that formation water is corresponding _total), and obtain Π _totalalong with the relation curve (see figure 1) of interface distance change, rock core displacement test result under irreducible water and residual oil condition is shown in that (line below represents recovery ratio and the relation curve injecting PV number when adopting stratum water drive displacement to Fig. 2, and when line above represents ion coupling water drive, recovery ratio is with the relation curve injecting PV number respectively.Can find out that ion coupling displacement water ratio stratum water drive improves recovery ratio about 15% from two curves).

In FIG, line is below the curve that formation water is corresponding, and under its expression formation water state, the interaction force of oil/water interface and water/rock interface shows as gravitation, and interface interaction power is negative value; Line is below curve corresponding to ion coupling water, and ion coupling water changes the active force at two interfaces, is repulsion, interface interaction power show as on the occasion of.The curve that in Fig. 1, formation water is corresponding demonstrates: the Π that formation water is corresponding _totalsome is less than 0, and this curve some present monotonically increasing trend, therefore, can carry out ion coupling water drive.

(6) Selective ion mode coupling water, its composition is as shown in table 3; According to ionic type and the Strength co-mputation Debye constant of ion coupling water; The Debye constant adopting formula (1) to calculate ion coupling aqueous systems is 1.04nm ^-1.

(7) measure the Hamaker constant of oil/water/rock, the Hamaker constant of its Crude Oil/ion coupling water/rock is 6.32 × 10 ^-21, adopt formula (2) to calculate Van der Waals force corresponding to ion coupling water, result is as shown in table 7.

(8) measure the Zeta potential of oil/ion coupling water and ion coupling water/rock interface, it is as shown in the table for result, and adopt formula (3) and formula (4) to calculate double electrode layer repulsion corresponding to ion coupling water, result is as shown in table 7.

(9) calculate structural capacity corresponding to ion coupling water in conjunction with the calculating of Dybye constant and formula (5), result is as shown in table 7.

(10) the micro force Π between rock/ion coupling water and ion coupling water/crude oil interface is calculated according to formula (6) _total(the Π that ion coupling water is corresponding _total) and Π corresponding to ion coupling water _totalrelation curve along with interface distance change: the oil/water/rock micro interface force profile of ion coupling water is shown in Fig. 1, and the rock core displacement test result under irreducible water and residual oil condition is shown in Fig. 2 respectively.

Curve as can be seen from above in Fig. 1: ion mates Π corresponding to water _totalall be greater than 0, and this curve presents the trend of monotone decreasing, illustrate that the composition of above-mentioned ion coupling water is applicable to this oil reservoir, can rock core displacement test be carried out;

(11), before rock core displacement test, dry 10 hours under first rock core (employing 1# rock core, 2# rock core carry out rock core displacement test simultaneously) being placed on 105 DEG C of conditions, the porosity and permeability value of testing rock core, test result is in table 5.

(12) rock core to be found time respectively saturated prime stratum water, then adopt 0.1,0.2,0.3,0.4 and the flow velocity test single-phase water of 0.5mL/min survey permeability, test result is in table 5.

(13) adopt mineral oil (viscosity is 9mPas) displacement rock core at ambient temperature, set up initial water saturation, the initial water saturation of final rock core is in table 5.

(14) adopt the oleic permeability under the flow velocity test initial water saturation condition of 0.05mL/min, test result is in table 5.

(15) at rock core being placed on 65 DEG C after aging 30 days, start flood pot test, displacement velocity is 0.05mL/min, record displacement time and accumulation produce oil data, finally calculates recovery ratio and the relation curve injecting PV.

Ion coupling water make the micro force of oil/water and water/rock interface be constant on the occasion of, and along with the increase of water film thickness reduces gradually, but formation water makes the micro force of oil/water and water/rock interface be negative value, shows as attraction, is unfavorable for the desorption of crude oil.

Rock core clay combining result tested by table 1

The component of table 2 Changqing oilfields crude oil

Mass ratio	Saturated hydrocarbons	Aromatic hydrocarbon	Non-hydrocarbons	Pitch
					wt%	65.05	23.3	6.68	4.97

The component of table 3 formation water and ion coupling water

The Zeta potential of the oil/water/rock interface obtained is tested in table 4 laboratory

Water type	Oil/water interface Zeta potential (mV)	Water/rock interface Zeta potential (mV)
			Prime stratum water	-7.7	-8.7
Ion coupling water	-21.73	-18.7

Table 5 rock core displacement test physical parameter and displacement efficiency compare

The Van der Waals force that table 6 prime stratum water is corresponding, structural capacity and double electrode layer repulsion

Van der Waals force, structural capacity and double electrode layer repulsion that table 7 ion coupling water is corresponding

Rock core displacement test result shows: ion coupling water improves recovery ratio 13.27-15.60% on the basis of conventional water drive, and this illustrates and adopts ion coupling water drive can obtain good oil displacement efficiency.

Claims (9)

1. ion coupling water drive improves a method for recovery ratio, and it comprises the following steps:

The detection of target low permeability sandstone reservoir:

According to ionic type and the intensity of the formation water of target low permeability sandstone reservoir, formula (1) is adopted to calculate the Debye constant of formation water:

$\mathrm{\κ}={(\underset{i}{\mathrm{\Σ}}{\mathrm{\ρ}}_{\∞i}{e}^2{Z}_i^2/{\mathrm{\ϵ}}_0\mathrm{\ϵkT})}^{1/2}---\left(1\right)$

In formula (1): k is Boltzmann constant, T is the absolute temperature of water, ε ₀for absolute dielectric constant, ε is medium relative dielectric constant, and i represents the ion in water; ρ _{∞ i}for ion concentration, unit is mol/L; Z _ifor the chemical valence of ion i;

Measure the Hamaker constant of the oil/water/rock of target low permeability sandstone reservoir, employing formula (2), (3) calculate Van der Waals force Π corresponding to formation water _{van-der-Woals}:

${\mathrm{\Π}}_{\mathrm{Van}-\mathrm{der}-\mathrm{Waals}}\left(h\right)=\frac{-A(15.96h\left(x\right)/\mathrm{\λ}+2)}{12\mathrm{\πh}{\left(x\right)}^3{(1+5.32h\left(x\right)/\mathrm{\λ})}^2}---\left(2\right)$

In formula (2), A is Hamaker constant; λ is London wavelength, and unit is nm; H (x) is the distance between oil/water and water/rock interface, and unit is nm;

Measure the oil/water of target low permeability sandstone reservoir and the Zeta potential of water/rock interface, employing formula (3), (4) calculate double electrode layer repulsion Π corresponding to formation water _electrical:

${\mathrm{\Π}}_{\mathrm{electrical}}\left(h\right)=n_b{k}_{B}T\left(\frac{2{\mathrm{\ψ}}_{r1}\left(x\right){\mathrm{\ψ}}_{r2}\left(x\right)\cosh \left(\mathrm{\κh}\left(x\right)\right)-{\mathrm{\ψ}}_{r1}^2\left(x\right)-{\mathrm{\ψ}}_{r2}^2\left(x\right)}{{\left(\sinh \left(\mathrm{\κh}\left(x\right)\right)\right)}^2}\right)---\left(3\right);$

ψ _x=ψ ₀e ^-κh(x)(4)

In formula (3), (4): r1, r2 represent the interface of oil/water, water/rock respectively; ψ _r1, ψ _r2be respectively oil/water, the Zeta potential value of water/rock interface in x direction; ψ ₀for oil/water, the Zeta potential value of water/rock interface in x=0 position, directly test draws; k _bfor bohr grows rigorously constant; ψ _r1for the Zeta potential at oil/water interface, unit is mV; ψ _r2for the Zeta potential of water/rock interface, unit is mV; κ is Debye length, and unit is m ^-1; A _kfor proportionality constant; E is elementary charge, and unit is C; n _bfor the ion number density in solution;

Structural capacity Π corresponding to formation water is calculated in conjunction with Dybye constant and formula (5) _structure:

${\mathrm{\Π}}_{\mathrm{structure}}=A_k\exp (-\frac{h\left(x\right)}{h_s})---\left(5\right);$

Wherein, h (x) is water film thickness distribution, and unit is nm; h _sfor Debye length characteristic;

Micro force Π between the rock/Shui Heshui/crude oil interface calculating target low permeability sandstone reservoir according to formula (6) _total, the Π that namely formation water is corresponding _total, and obtain Π corresponding to formation water _totalrelation curve along with interface distance change:

Π _Total=Π _structure+Π _electrical+Π _{Van-der-Woals}(6)；

If the Π that formation water is corresponding _totalall be greater than 0, and the Π that formation water is corresponding _totalrelation curve entirety along with interface distance change presents the trend of monotone decreasing, and so this target low permeability sandstone reservoir need not adopt ion coupling water to carry out water drive operation; If the Π that formation water is corresponding _totaland inequality is greater than 0 or Π corresponding to formation water _totalalong with a part for the relation curve of interface distance change presents monotonically increasing trend, then ion coupling water is adopted to carry out water drive operation to this target low permeability sandstone reservoir;

The selection of ion coupling water:

According to the salinity Selective ion mode coupling water of the formation water of target low permeability sandstone reservoir, according to ionic type and the intensity of this ion coupling water, formula (1) is adopted to calculate the Debye constant of ion coupling water;

Measure the Hamaker constant of the oil/water/rock between the crude oil of ion coupling water and target low permeability sandstone reservoir, rock, adopt formula (2) to calculate Van der Waals force Π corresponding to ion coupling water _{van-der-Woals};

Measure the oil/water between the crude oil of ion coupling water and target low permeability sandstone reservoir, rock and water/rock interface Zeta potential, employing formula (3), (4) calculate double electrode layer repulsion Π corresponding to ion coupling water _electrical;

Structural capacity Π corresponding to ion coupling water is calculated in conjunction with Dybye constant and formula (5) _structure;

According to the micro force Π between rock/Shui Heshui/crude oil interface that formula (6) calculates between ion coupling water and the crude oil of target low permeability sandstone reservoir, rock _total, the Π that namely ion coupling water is corresponding _total, and obtain Π corresponding to ion coupling water _totalalong with the relation curve of interface distance change;

If the Π that ion coupling water is corresponding _totalall be greater than 0, and the Π that ion coupling water is corresponding _totalrelation curve entirety along with interface distance change presents the trend of monotone decreasing, so carries out rock core fluidity test; If the Π that ion coupling water is corresponding _totaland inequality is greater than 0 or Π corresponding to ion coupling water _totalalong with a part for the relation curve of interface distance change presents monotonically increasing trend, then adjust the composition of ion coupling water, reduce salinity, improve the content of dianion, recalculate the Π that ion coupling water is corresponding _total, and obtain Π corresponding to new ion coupling water _totalalong with the relation curve of interface distance change, until the Π that ion coupling water is corresponding _totalall be greater than 0, and the Π that ion coupling water is corresponding _totalrelation curve entirety along with interface distance change presents the trend of monotone decreasing;

Rock core fluidity test:

Utilize rock core formation water and ion coupling water to carry out rock core fluidity test, obtain recovery ratio and the relation curve injecting PV number;

If the recovery ratio that ion coupling water is corresponding is all greater than recovery ratio corresponding to formation water, then determines that this ion coupling water is applicable to this target low permeability sandstone reservoir, and carry out water drive operation;

If the recovery ratio that ion coupling water is corresponding is not all greater than recovery ratio corresponding to formation water, then determine that this ion coupling water is not suitable for this target low permeability sandstone reservoir, the composition of adjustment ion coupling water, reduce salinity, improve the content of dianion, re-start and calculate Π corresponding to ion coupling water _total, obtain Π corresponding to new ion coupling water _totalalong with relation curve and the rock core fluidity test of interface distance change, until the recovery ratio that ion mates water corresponding is all greater than recovery ratio corresponding to formation water, carry out water drive operation afterwards.

2. method according to claim 1, wherein, described λ=1.00E+02nm, k _b=1.38E-23JK ^-1, T=2.98E+02K, hs=5.00E-02nm, e=1.602E-19C, ε ₀=8.85 × 10 ^-12farad/rice.

3. method according to claim 1, wherein, the relative dielectric constant of water is 78.36, and the relative dielectric constant of oil is 7.3, and the relative dielectric constant of rock is 8.0.

4. method according to claim 1, wherein, the value of described h (x) is 0.4-20mm, preferred 0.5-20mm.

5. method according to claim 1, wherein, the salinity of described ion coupling water is not less than the critical water-sensitive salinity of target low permeability sandstone reservoir.

6. method according to claim 1, wherein, containing Ca in described formation water ²⁺and Mg ²⁺.

7. the method according to claim 1 or 6, wherein, the salinity of described formation water is not less than 10000mg/L, Ca ²⁺and Mg ²⁺content sum be not less than 100mg/L.

8. method according to claim 1, wherein, described ion coupling water contains Ca ²⁺and Mg ²⁺.

9. the method according to claim 1 or 8, wherein, with the stereometer of ion coupling water, the composition of described ion coupling water comprises: K ⁺+ Na ⁺content be 1900mg/L, Ca ²⁺content be 200mg/L, Mg ²⁺content be 30mg/L, HCO ₃ ^-content be 30mg/L, Cl ^-content be 3199mg/L, SO ₄ ^2-content be 210mg/L, salinity is 5569mg/L.