SU1514918A1 - Method of determining saturation of gas condensate-bearing formation with liquid hydrocarbons - Google Patents

Abstract

The invention relates to the development of gas condensate fields. The goal is to improve the accuracy of the method and provide the possibility of obtaining quantitative information about the saturation of the reservoir with liquid hydrocarbons. For this purpose, an indicator and an inert indicator with a carrier gas are injected into the formation soluble in liquid hydrocarbons (ASU). The times of occurrence of indicators in the production of a production well are recorded. The densities of the liquid and gas phases of the formation fluid are determined. The distribution coefficients of the soluble in the PSU and inert to them indicators are determined. Determine the reservoir porosity coefficient. The average filtration rate of the indicator carrier gas is determined. The saturation of the gas condensate layer of the PSU is calculated by the formula: S = (T ₁ -T ₂ ) ^. Vρ _g / K _p ^{. L.} (K ₁ -K ₂ ) ^. ρ _W , where ρ _g , ρ _W - density, respectively, of the gas and liquid phases

K ₁ , K ₂ - distribution coefficient, respectively, soluble in the PSI and inert to them indicators

K _N - coefficient of porosity

V - average filtration rate of the gaseous carrier of indicators

T ₁ , T ₂ - the time of occurrence in the production of the production well, respectively, soluble in PSU and inert indicators to them

L is the length of the reservoir. In addition, dichloroethane or dichloroformethane, or chloroform, is pumped as soluble indicators in the PSUs. As an inert indicator for ZhUV, helium is injected. 1 hp f-ly.

Description

The invention relates to the field of development of gas condensate fields, in particular, to methods for determining the reservoir formation of liquid hydrocarbons, and can be used to control the development of gas condensate field sites and to develop gas condensate fields.

reservoir pressure (cycling process).

The purpose of the invention is to increase the accuracy of the method and to provide the possibility of obtaining quantitative information on the formation of liquid hydrocarbons.

The solubility of halogen derivatives of hydrocarbons in the condensate leads

315

to the front lag of propagation relative to the gas displacement front. In contrast, filtering the gels in the gas phase and its stability to the condensate ensures its rapid advance to the production well.

According to the difference in arrival time of indicators of different solubility to the producing (production) wells, taking into account the reservoir properties of the reservoir, it is possible to judge the saturation of the reservoir with the liquid phase.

I

The method is carried out as follows.

A indicator and an inert indicator with a gaseous carrier of the latter are pumped into the reservoir through the injection well successively into the reservoir. Record the times of occurrence of indicators in the production of an extruded well. The densities of the liquid and gas phases of the formation fluid are determined, the distribution coefficients of the soluble in liquid hydrocarbons and inert indicators thereto are determined, the coefficient of porosity of the formation is determined. The average filtration rate of the gas carrier of the indicators is determined, and the saturation of the gas condensate formation with liquid hydrocarbons is determined from the expression:

S

(ta) .V wg

Kn-L (,

de fr P density, respectively, of the gas and liquid phases, kg / m; .40

K, K is the distribution coefficient, respectively, of the soluble in hydrocarbons and inert indicators to them; 45 K - coefficient of porosity

reservoir;

V is the average rate of filtration of the gaseous carrier of indicators; 50 t ,, t., Is the time of appearance in the production of a production well, respectively, soluble in liquid hydrocarbons and inert indicators — 55 to them; L - the length of the reservoir, m. As the indicators soluble in liquid hydro-gases, they are injected

tO

15

th - th. about ,

20

25

thirty

35

, 40

45

184

dichloroethane or dichlorofluoromethane or chloroform, and as an indicator inert to liquid hydrocarbons, helium.

The use of these halogen derivatives of light hydrocarbons is due to the proximity of their molecular masses to the molecular weight of the light portion of the condensate, boiling points and good solubility in liquid hydrocarbons. This provides low vapor pressure of these indicators in the gas-condensate system of the reservoir, which is comparable with the sorbability of hydrocarbons by the rock, sorbability, and filtering them as part of a liquid-phase hydrocarbon mixture in the reservoir.

The use of gels is due to its minimum solubility of all gases in liquid hydrocarbons, and therefore, its filtration in the reservoir only as part of the gas phase. In addition, these indicators meet the general requirements imposed on indicators that are artificially introduced into the reservoir: chlorine (fluorine) - hydrocarbons are absent in the reservoir, i.e. it does not have their background content; helium is present in natural gases at sufficiently low concentrations and is required: the volume of its injection is therefore small.

Example. The injection and production wells located at a distance of 1000 m are selected at the field. The average thickness of the reservoir is exposed by wells, h 50 m. The porosity of the reservoir, determined from the study of core material, 0.11. The production well rate q is measured. 10, the software for which the average filtration rate of the gaseous indicator carrier (gas) in the reservoir is calculated:

V

 20 m / day.

pykno., 3

hB 50-1000 The density of the gazg is determined by the metric method j3 | - 0.7 kg / m and the density of the liquid phase by the densimetric method p (; 700 kg / m. The distribution coefficients of the indicators are determined by any known method (experimentally or calculated by). For example, for dichloroethane K, 0.97; for gels, K 0.00038.

The required number of indicators for injection into the reservoir is determined.

 The required amount of gels is determined by the formula:

Not

 P ,. 2

I

ten

-

The molecular diffusion coefficient is taken from reference literature D. The distance between the bellows and the injection wells L 1000 m.

0.7.0.11

1000-2 Js,

14

ten

TOGO

-, - i

. 2.38-10 kg or 12.34 m.

The required amount of dichloroethane is determined by the formula:

Q. fr-Kn l ..j7f.10- Whhelg J D

п 7 л 11 1 X 70Ц 0 97 „L ,, 1 0.7-0.1M

1000

V-

vIO- 0.347 kg ..

0.347 kg of dichloroethane is pumped into the injection well with the pump unit and with the help of a compressor - 12 m of gels and they are forced into the reservoir with reservoir gas in a volume of 54 m-. The time of occurrence of gels in the production of a production (production) well is recorded for 40 days. The time of occurrence of dichloroethane in the production of an additional well of t .55 days is recorded. -WITH -

The saturation of the reservoir with liquid hydrocarbons is determined from the expression:

(t.-t -U- rg 15-20-07 Kr, -L (K-K ,,) - f -1000 O, 969.70 0.0028.

Thus, the saturation of the reservoir with liquid hydrocarbons in the studied area of 0., 28%. ,

Using the invention to determine the saturation of a reservoir with liquid hydrocarbons provides, in comparison with known methods, a more accurate and less laborious determination of the saturation of a reservoir with liquid carbohydrates.

ten

15

20

00 j

d,

increase of the final condensate and gas recovery gas condensate reservoir.

In addition, this method is practically not sensitive to the loss of indicators in the reservoir, which significantly increases its accuracy and reliability.

Claims (2)

1. A method for determining the saturation of a gas-condensate reservoir with liquid hydrocarbons by sequential injection into the reservoir through the injection well of a liquid-soluble indicator hydrocarbon and an inert indicator for them with a gaseous carrier and the subsequent recording of the time of occurrence of indicators in the production of a production well, To increase accuracy and provide quantitative information on the saturation of the reservoir with liquid hydrocarbons, the densities f and f are determined liquid and gas phases of the reservoir fluid, the K and K coefficients of the distribution of soluble in liquid hydrocarbons and inert indicators, the coefficient of porosity of the reservoir K, the average filtration rate V of the gaseous indicator carrier, and the saturation of the gas condensate reservoir with liquid hydrocarbons determined from the expression H (t, - Lg) - K, L- (K - i P fx where t ,, t is the time of occurrence in production of a production well, respectively, soluble in liquid hydrocarbons and inert shadikator to them, with; L - formation length, m 2. POP.1 method, different from and. with the fact that as soluble in liquid hydrocarbons ind30 35 5Q of the cator is injected with dichloroethane, or dichlorofluoromethane, or chloroform, and as inert to liquid hydrocarbons