CN102207491B - Method for measuring low-temperature oxidation reaction rate of light crude oil - Google Patents

Abstract

The invention relates to a method for measuring a low-temperature oxidation reaction rate of a light crude oil in laboratory experiment research for improving yield of an oil field. In the method, a sample mixing device is used as a reaction container; the amount of solution gas is calculated according to a gas-oil ratio which is obtained through single degassing experiments of the crude oil at different reaction stages; gas cap gas amounts at different reaction stages, and the crude oil amount and oxygen consumption amount in the oxidation reaction are calculated according to the mass conservation law and constitution change situations of the gas cap gas and the solution gas; and the average low-temperature reaction rate of the crude oil at different reaction stages is calculated on the basis of the gas cap gas amount and the crude oil amount and oxygen consumption amount. According to the method in the invention, the average oxidation reaction rate values of the crude oil at different stages are exactly measured so as to provide foundation data for calculating crude oil oxidation reaction kinetic parameters and comparing reaction activities between different crude oils.

Description

The assay method of light crude low-temperature oxidation reaction rate

Technical field

The present invention relates to a kind of assay method of light crude low-temperature oxidation reaction rate, belong to agent for improving oilfield recovery in-house laboratory investigation technical field.

Background technology

Before implementing light oil reservoirs high pressure air injection and air injection foam and improving the recovery ratio project, need to carry out resident fluid laboratory study and data evaluation, in order to help to determine, operation conditions optimization.Wherein, the mensuration of crude oil low-temperature oxidation reaction rate is the basis of calculating crude oil oxidation reaction kinetics parameter, can its size fully consume oxygen before not only being related to air arrival producing well, oxygen concentration is reduced under the critical dissolved oxygen concentration, guarantee production safety, and be related to the complexity of the spontaneous formation of combustion front, the raising of recovery ratio there is material impact.At present, there is bibliographical information to adopt the Pressure Drop method to measure the low-temperature oxidation reaction rate of crude oil both at home and abroad, such as article " air injection foam low temperature oxidation technology improves recovery test " (China University Of Petroleum Beijing's journal, the 4th phase in 2009: 94-98) described, usually in the test duration scope, the pressure decreased that the dissolving of air in the stratum causes is far longer than because the pressure decreased that oxygen expenditure causes, and the method is not considered in pressure decreased that the dissolving of air in in-place oil causes and the course of reaction because gaseous component forms and changes the pressure that causes and change, and the reaction rate value and the actual value deviation that cause the method to be measured are excessive; Simultaneously, because the dissolution degree difference of air in different crude oils lacks comparability between the different crude oils oxidizing reaction rate that the method is measured.The change calculations low-temperature oxidation reaction rate that is also formed by monitoring core flowing experiment outlet output gas component by bibliographical information, such as article " the solidifying oily air-injected low-temperature oxidation thing mould research of Cao Taigao " (drilling technique, o. 11th in 2008: 113-115) described, the method is not considered the impact that the difference of the variation of gas phase saturation in the dissolving of air in crude oil, the core and oxygen and nitrogen solubility forms output gas component, and measurement result and actual value have relatively large deviation.

Summary of the invention

The objective of the invention is the defective that the oxidizing reaction rate measurement result that exists for above-mentioned technology and actual value have relatively large deviation, a kind of assay method that can Accurate Determining light crude low-temperature oxidation reaction rate is provided.

The assay method of light crude low-temperature oxidation reaction rate provided by the present invention, carry out in accordance with the following steps:

(1) the dead oil sample of the scene being fetched changes in the dehydrating apparatus and dewaters, and dewaters qualified rear for subsequent use;

(2) with air compressing to the sample device, constant temperature is to T _Air, constant voltage is to reservoir pressure P _fMore than 4 hours, stand-by;

The dead oil sample that (3) will dewater qualified changes in the sample device as reaction vessel, the crude quality W that record changes over to _Oil, constant temperature is to temperature of reaction, and constant voltage is to reservoir pressure P _fMore than 4 hours; The dead oil sample mix that adopts the double pump method that ready pressurized air is changed in this sample device and changed over to, the pressurized air volume V that record changes over to _Air

The sample device constant temperature and pressure that (4) will change crude oil and air over to is to temperature of reaction and pressure, stir and writing time t ₀

(5) before the sampling, with the air of helium purge sampling system noresidue to the system, record accumulative total reaction time t _mTaking out volume from the sample device is V _CmGas cap gas, utilize gas chromatograph to analyze gas cap gas and form; From the sample device, take out an amount of crude oil and carry out the single degassing experiment, the quality W of record gas-free oil _mVolume V with solution gas _Sm, adopt gas chromatograph to analyze the composition of solution gas; Atmospheric temperature T when recording every sub-sampling _mWith atmospheric pressure P _m

(6) repeating step 5 to reaction finishes;

(7) suppose that quality remains unchanged in the gas-free oil course of reaction, calculate by the following method the low-temperature oxidation reaction rate value of obtaining crude oil:

(1)

In the formula:

n _AirChange the amount of the air in the reaction sample device over to, mol;

T _AirCompressed air temperature, K;

P _fReservoir pressure, MPa;

The Z temperature T _Air, pressure P _fThe time air deviation factors;

The R mol gas constant, 8.31451MPamL/(molK);

V _AirChange the volume of air in the reaction sample device over to, mL.

(2)

In the formula:

n _CmThe amount of the gas cap gas that takes out during the m sub-sampling, mol;

V _CmThe gas cap gas volume that takes out during the m sub-sampling, mL;

T _mAtmospheric temperature during the m sub-sampling, K;

P _mAtmospheric pressure during the m sub-sampling, MPa.

(3)

In the formula:

n _SmThe amount of the solution gas that takes out during the m sub-sampling, mol;

V _SmThe solution gas volume that takes out during the m sub-sampling, mL.

(4)

In the formula:

n _StmThe amount of total solution gas before the m sub-sampling, mol;

W _OilChange the gas-free oil quality in the reaction sample device over to, g;

W _mThe gas-free oil quality of discharging during the m sub-sampling, g.

(5)

[0008]In the formula:

n _CtmTotal pneumatic jack tolerance before the m sub-sampling, mol;

Y _SmjThe molar content of j component in the m sub-sampling solution gas, %;

Y _CmjThe molar content of j component in the m sub-sampling gas cap gas, %.

(6)

In the formula:

Crude oil oxygen utilization between m-1 sub-sampling to the m sub-sampling, mol.

(7)

[0010]In the formula:

ν _mThe average oxygen consumption rate of crude oil between m-1 sub-sampling to the m sub-sampling, mol/ (hg);

t _mThe accumulative total reaction time during to the m sub-sampling, h.

The invention has the beneficial effects as follows the sample device as reaction vessel, calculate the amount of solution gas in the crude oil by the output gas oil ratio of differential responses stage crude oil single degassing experiment acquisition, form situation of change by measure air and crude oil system that the low-temperature oxidation reaction occurs in the sample device in the component of differential responses stage gas top gas and solution gas, calculate the pneumatic jack tolerance of the variant stage of reaction according to law of conservation of mass, participate in former oil mass and the oxygen expenditure amount of oxidation reaction, accurately calculate based on this average response speed of differential responses stage crude oil low-temperature oxidation reaction, for the contrast of reactivity between the calculating of crude oil oxidation reaction kinetics parameter and different crude oils provides basic data.

Specific embodiment

The invention will be further described below by embodiment, but be not the restriction to assay method of the present invention.

Embodiment one: certain crude oil is at temperature 363.15K, the mensuration of low temperature oxidizing reaction rate under the pressure 23.5MPa.

After the dead oil sample dehydration of 1, the scene being fetched is qualified, for subsequent use.

2, with air compressing to the sample device, constant temperature is at 343.15K, constant voltage is to more than 23.5MPa4 hour, and is stand-by.

3, the dead oil after the 291.23g dehydration is changed in the sample device as reaction vessel, constant temperature is to 363.15K, and constant voltage is to more than 23.5MPa4 hour; Adopting the double pump method that the pressurized air (343.15K, 23.5MPa) of 150.95mL is changed in this sample device mixes with crude oil.

The sample device constant temperature that 4, will change crude oil and air over to is at 363.15K, and constant voltage stirs and writing time at 23.5MPa.

5, accumulative total react 48,96,144,192, behind the 240h, take out respectively a small amount of gas cap gas, the gas cap gas volume that record is discharged utilizes gas chromatograph to analyze gas cap gas and forms, and discharges a small amount of crude oil and carries out the single degassing experiment, the quality of record gas-free oil and the volume of solution gas, adopt gas chromatograph to analyze the composition of solution gas, at first use before every sub-sampling more than the helium purge sampling system 5min, the remaining air of nothing in the assurance system, recording reacting time, atmospheric temperature and pressure.Data during each sub-sampling are as shown in table 1:

General data during each sub-sampling of table 1

6, data preparation: by above-mentioned data processing method, the average oxidizing reaction rate that obtains each stage is as shown in table 2:

The average oxidizing reaction rate in each stage of table 2 crude oil

Embodiment two: certain crude oil is at temperature 383.15K, the mensuration of low temperature oxidizing reaction rate under the pressure 23.5MPa.

After the dead oil sample dehydration of 1, the scene being fetched is qualified, for subsequent use.

2, with air compressing to the sample device, constant temperature is at 343.15K, constant voltage is to more than 23.5MPa4 hour, and is stand-by.

The dead oil sample that 3, will dewater qualified changes in the sample device as reaction vessel, and the crude quality that changes over to is 307.64g, and constant temperature is to 383.15K, and constant voltage is to more than 23.5MPa4 hour.Adopting the double pump method that the pressurized air (343.15K, 23.5MPa) of 162.17mL is changed in this sample device mixes with crude oil.

The sample device constant temperature that 4, will change crude oil and air over to is to 383.15K, and constant voltage stirs and writing time to 23.5MPa.

5, accumulative total react 24,48, behind the 72h, take out respectively a small amount of gas cap gas, the gas cap gas volume that record is discharged utilizes gas chromatograph to analyze gas cap gas and forms, and discharges a small amount of crude oil and carries out the single degassing experiment, the quality of record gas-free oil and the volume of solution gas, adopt gas chromatograph to analyze the composition of solution gas, at first use before every sub-sampling more than the helium purge sampling system 5min, the remaining air of nothing in the assurance system, recording reacting time, atmospheric temperature and pressure.Data during each sub-sampling are as shown in table 3:

General data table during each sub-sampling of table 3

6, data preparation: by above-mentioned data processing method, the average oxidizing reaction rate that obtains each stage is as shown in table 4:

The average oxidizing reaction rate in each stage of table 4 crude oil

Claims (4)

1. the assay method of light crude low-temperature oxidation reaction rate is characterized in that described assay method carries out in accordance with the following steps:

(1) the dead oil sample of the scene being fetched changes in the dehydrating apparatus and dewaters, and dewaters qualified rear for subsequent use;

(2) with air compressing to the sample device, constant temperature is to T _Air, constant voltage is to reservoir pressure P _fMore than 4 hours, stand-by;

The dead oil sample that (3) will dewater qualified changes in the sample device as reaction vessel, the crude quality W that record changes over to _Oil, constant temperature is to temperature of reaction, and constant voltage is to reservoir pressure P _fMore than 4 hours; The dead oil sample mix that adopts the double pump method that ready pressurized air is changed in this sample device and changed over to, the pressurized air volume V that record changes over to _Air

The sample device constant temperature and pressure that (4) will change crude oil and air over to is to temperature of reaction and pressure, stir and writing time t ₀

(5) before the sampling, purge the air of sampling system noresidue to the system, record accumulative total reaction time t _mTaking out volume from the sample device is V _CmGas cap gas, utilize gas chromatograph to analyze gas cap gas and form; From the sample device, take out an amount of crude oil and carry out the single degassing experiment, the quality W of record gas-free oil _mVolume V with solution gas _Sm, adopt gas chromatograph to analyze the composition of solution gas; Atmospheric temperature T when recording every sub-sampling _mAnd pressure P _m

(6) repeating step 5 to reaction finishes;

(7) suppose that quality remains unchanged in the gas-free oil course of reaction, calculate the pneumatic jack tolerance of the variant stage of reaction, former oil mass and the oxygen expenditure amount of participation oxidation reaction according to law of conservation of mass, calculate based on this average response speed of differential responses stage crude oil low-temperature oxidation reaction.

2. the assay method of light crude low-temperature oxidation reaction rate according to claim 1 is characterized in that adopting helium that the air in the sampling system is purged displacement.

3. the assay method of light crude low-temperature oxidation reaction rate according to claim 1 and 2 is characterized in that in the data handling procedure, and the amount of solution gas is calculated as follows:

$n_{\mathrm{stm}}=\frac{(W_{\mathrm{oil}}-\underset{i=0}{\overset{m-1}{\mathrm{\Σ}}}{W}_i)n_{\mathrm{sm}}}{W_m}$

In the formula:

n _StmThe amount of total solution gas before the m sub-sampling, mol;

W _OilChange the dead oil quality in the reaction sample device over to, g;

n _SmThe amount of the solution gas that takes out during the m sub-sampling, mol;

W _mThe gas-free oil quality of discharging during the m sub-sampling, g.

4. the assay method of light crude low-temperature oxidation reaction rate according to claim 1 and 2 is characterized in that in the data handling procedure, and the amount of gas cap gas is calculated as follows:

$n_{\mathrm{ctm}}=\frac{78n_{\mathrm{air}}-\underset{i=0}{\overset{m-1}{\mathrm{\Σ}}}{n}_{\mathrm{si}}{Y}_{{\mathrm{siN}}_2}-\underset{i=0}{\overset{m-1}{\mathrm{\Σ}}}{n}_{\mathrm{ci}}{Y}_{\mathrm{ci}{N}_2}-n_{\mathrm{stm}}{Y}_{\mathrm{sm}{N}_2}}{Y_{\mathrm{cm}{N}_2}}$

In the formula:

n _CtmTotal pneumatic jack tolerance before the m sub-sampling, mol;

n _AirChange the amount of the air in the reaction sample device over to, mol;

n _CmThe amount of the gas cap gas that takes out during the m sub-sampling, mol;

Y _SmjThe molar content of j component in the m sub-sampling solution gas, %;

Y _CmjThe molar content of j component in the m sub-sampling gas cap gas, %.