RU1822459C - Method of evaluating seam insulation in oil-and-gas bearing holes - Google Patents

Description

to 1 (f) nsvii); 2 and 3 measurements of temperature-iypi i in the process of injection of insulating material A, 5 and 6 thermograms recorded 1, 3 and 4 hours after washing the wellbore. Figure 2 shows the curve of the dependence of the heating anomaly in the interval of the formation from time to time.

The method is carried out as follows.

Prior to injection, they provide the addition of heat-generating components to the insulating material. The thermometer is run and the temperature distribution is measured along the wellbore (background measurement. Then, insulating material is pumped in before the tubing is received, and a series of temperature measurements are carried out during the filling of the fluid and the insulation material into the formation. Temperature measurement during the filling process The insulating material is typically produced by injecting insulating materials with reduced viscosity.

flushing the wellbore and register

a series of thermogrism after washing. According to the obtained thermal programs, the intervals of absorption of the insulating material, the intervals of heat generation due to the presence of the insulating material, and the dependence of the anomaly of the temperature oi of the premium are determined by the oedius of the absorption zone of the insulating material according to the procedure described below.

As an objective assessment of the quality of formation isolation and determination of R, the off-radius radius of the support zone, the following simple technique was used, which is based on

the relationship between the initial pressure gradient o (Pa / m), the ultimate shear stress Go (Pa), the critical radius of the absorption zone of the insulating material i RKP (m) and the depression in the isolated formation Д Р (Pa)

and

LR

NKR

From here, one can explicitly obtain RKp.

DR

Kcr - - g The value of o can be estimated using the known relation

(,

where C is dimensionless constant and has order

k is the permeability coefficient of the formation (for high permeability formations 10 m, for low permeability 10 m).

The G0 values of long-range oils are 10 Pa, while for gelling agents, a G0 value of the order of 103 Pa should be taken.

Let us now evaluate n for low permeability and high permeability formations

Pnp-10 2103Pa (10 12m2) -1 / 2-107Pa / mf / VP-U Ch03Pz (10 10m2) 1 / 2-106Pa / m.

Then the RKp values will accordingly be equal (for depression D P of the order of 100 atm 10 Pa):

15 0

5

 ABOUT

5

0

5

0

5

cr np

R

cr vp

107Pa

107 Pa / m

107Pa

1m,

- 10 m.

10 ° Pa / m

Thus, with the value of the radius of the absorption zone of the insulating substance R RKp, the insulation should be considered poor-quality, and with R - Ckr - high-quality.

Example. In FIG. Figure 1 illustrates the determination of the absorption intervals of the insulating material and the intervals of its presence after washing.

The insulated formation (2154-2162 m) is perforated in the R interval of 2154.2 21 GO m. According to the thermograms during the injection process, the lower boundary of the absorbing interval, which is confined to the bottom of the formation by 1 luine 162 m, is determined according to the anomalies of heating, gea in the internal / hr: 2 .2 21618m, power generator of 1.6 m The diagram also illustrates the methods for determining the heating anomalies of Ti, 72 and 1, h at different points in time,

Figure 2 shows the time dependence of the temperature anomaly used to determine the effective radius of the absorption zone of the insulating material. The effective radius was calculated from the dependence presented in the claims. Previously, this dependence was converted to

w / 8aTi 2-: T2 i b 2

vM 12

When the coefficient of thermal diffusivity a is 0.002 m / h, the radius of the zones is k; heating was about 30 cm. The total amount of absorbed layers of insulating substance (with an average porosity of 0.2) was for each meter of power of the absorbing interval

, 0.06. .

Nm

Let us calculate the total amount of insulating material absorbed by the low-permeability interlayer required for

high-quality isolation of the interlayer. through the above np value

- --tlRZrip 0.2 3.14-1 m2 0.63-NM

Qm3

In the above example, 0.06 -,

Nm

those. It differs by order, which allows us to conclude that the isolation of the layer is of poor quality.

It is possible to compare the values of injections into the isolated interlayer Q cr and Q:

m31

Approx. 4.6 m 0.63 - 3 m3;

M

0, P 4.6mO, 06 - -0.3m3;

M

those. the amount of injected insulating material was not sufficient for high-quality isolation of the interlayer.

From the practice of downhole research, it is known that a simple well during isolation work by cementing is at least 10 days under the most favorable conditions (about 2 weeks).

The proposed method, as is known, does not require well shutdown; it is more technologically advanced and efficient than previously known methods of isolating formations.

The proposed method, in comparison with the known ones, improves the accuracy of determining the radius of the injection zone of insulating material;

to improve the technology of repair and insulation works;

increase the uniqueness of determining isolation intervals;

assess the quality of isolation of formations and intervals of annular movement of water;

Claims (1)

to reduce the contribution of natural thermal convection to the well sump, which allows to increase the accuracy of determining the lower boundary of the absorption interval of the insulating material, and ultimately to increase the efficiency of the quality control of the injection of insulating material. SUMMARY OF THE INVENTION A method for evaluating the quality of formation isolation in oil and gas wells, including injecting insulating wells into the well materials, measuring the temperature distribution along the well table before and after injection of insulating material, comparing thermograms, identifying intervals of absorption of insulating material by temperature anomalies and assessment of the quality of formation isolation, characterized in that, in order to increase the assessment efficiency, simultaneously with the injection of insulating material into the borehole, the temperature distribution along the wellbore is repeatedly measured, the thermal diffusivity of the formation is determined, as of the insulating material, a gelling material with heat-generating or heat-absorbing additives is used, and the quality of the insulation of the layers is judged by the value of the effective radius of the absorption zone of the insulating material Which is determined from the expression: R2 Ti T2 1-exp () Rz )  - “(-t. where Ti and T2 - the value of the temperature anomaly at time ti and tz, respectively, K; a is the coefficient of thermal diffusivity of the formation, m / s; R is the effective radius of the absorption zone of the insulating material, m. ps 2160 i gfb t # + t; with t h FIG 2 Figure 1 fe it r -v, v