SU825885A1 - Deep-well pressure gauge - Google Patents

Description

(54) depth gauge

The invention relates to the oil industry, in particular to the study of wells. . The well-known deep Helix man-mert is contained, which contains a clock mechanism, a friction clutch, a lead screw, a carriage, with a feather and a Helix ll. The disadvantages of the known gauge are the presence of residual deformations of the helix, which lead to the need for frequent calibration after a small number of measurements and the discrepancy between the pressure values during the forward and reverse run (the presence of hysteresis). The closest solution known to the present invention is a depth gauge comprising a housing with chambers, one of which houses a pressure recorder and a stem with a separator, and the other chamber is filled with f2 liquid. This pressure gauge has a drawback: the effect of a change in the temperature of the external (borehole) medium on its readings due to the thermal expansion of the fluid in the chamber. At the same time, the effect of temperature on the instrument readings exceeds the effect of the measured value itself — pressure. For example, when olive oil is used as a liquid for a temperature difference of At 200 ° C and pressures of DRUOO of kgf / cm, the change in the volume of liquid in the chamber under the effect of a change in pressure d relative to the initial volume is. 5ХЗЬР. p, -dr b, 3-10, where | a is the compressibility factor of the liquid (olive oil) equal to 6.3-10-5. The change in the volume of fluid in the chamber under the action of a temperature change with respect to the initial volume V. is (.-4t 14-10 -, 8-10 where oCrjf: is the coefficient of thermal expansion of the liquid (olive oil) equal to 7410 ° C. Thus, the relative the change in the volume of the liquid in the chamber as a function of temperature is 2.3 times greater than its relative change in pressure, i.e., the error in measuring the temperature of the temperature strongly influences the readings of the anometer.

The purpose of the invention is to increase the accuracy of the gauge.

The goal is to achieve that the chamber filled with a liquid is divided by an elastic placer, the upper part of it is packed with a rod and communicating with the external space, and its lower part is made two-step, in the lowest step of which the upper end of the stem is placed, and the dimensions of the rotary chamber jumpers and strings are related by

Di

oi,

LC

Bk

odK-oic

two-step length L

where are cameras, CM;

fc: rod length, cm; diameter of the upper (larger) stage of the two-stage chamber or lintel length, cm; the diameter of the lower (meni) neck of the two-stage Ks1mer, cm;

the coefficient of thermal expansion of the fluid in a two-stage chamber;

, with the coefficient of linear thermal expansion of the materials of the housing, chamber and rod.

The drawing shows a diagram of the proposed depth gauge, General view.

Depth gauge contains a clock mechanism 1, the shaft 2 of which enters the chamber 3 through the adapter 4 and is poorly sealed by a ring 5 of a deformable material. The shaft 2 is connected to the cartogram holder 6. The pen 7 is mounted on the rod 8. The cartogram holder 6 is located in the chamber 3 of the housing 9. The rod 8 passes through the cylinder 10, compacted by a weakly clamped ring 11 of deformable material, into the chamber 12 completely filled with any Liquid, for example, olive oil.

In the chamber 3 there are holes 13 with a filter. A thermometer 14 is placed at the bottom of the pressure gauge to measure the temperature. Chamber 12 is made in two steps. The bottom stage has a smaller diameter compared to the top. Above the chamber 12 an additional chamber 15 is placed, separated from the chamber 12 by a flexible jumper 16, for example, a bellows. The jumper 16 is connected to one end of a rigid rod 17 placed in an additional chamber 15. The other end of this rod is rigidly attached to the upper part of the camera 15

In the additional chamber 15 there are made through holes 18 with a filter, which communicate this chamber with the external (borehole) medium.

The pressure gauge works as follows.

The outer (borehole) pressure through the holes 13 in the housing 9 is transferred to the chamber 3 and acts on the rod 8, which, when moved, compresses the fluid in the two-stage chamber 12 until its pressure becomes equal to the pressure of the external (downhole) medium.

At the same time, the external pressure. Through the opening 18 is transferred to the additional chamber 15 and acts on the flexible jumper 16. As a result of the fluid being compressed in the two-stage chamber 12 by the rod 8, the pressure in this chamber is constantly kept equal to the external pressure, i.e. pressure drops are absent. In this way, the conditions for any passage of liquid from the two-stage chamber 12 between the rod 8 and the ring 11 are completely eliminated and, at the same time, the conditions for measuring any high pressures are created.

The movement of the rod 8 is transmitted to a writing pen 7 which is rigidly associated with it and which it draws on a cartogram attached to the cartographic holder 6.

. As the temperature increases, the fluid in the two-stage chamber 12 expands. To compensate for this expansion, the volume of the two-stage chamber 12 ,. the materials of the body over the length of the two-stage 12 and the additional 15 chambers, as well as the rods 17 are selected so that the change in the volume of the two-stage chamber 12 by moving the flexible jumper 16 upward, caused by thermal expansion of the body over the length of the chambers 12 and 15, is equal to the increase in the volume of the fluid in the two-stage chamber 12 due to thermal expansion of this fluid. As a result, the rod 8 with the pen 7 fixed on it remains stationary at constant pressure, as a result of which the temperature change does not reflect on the manometer readings.

The condition for compensating for thermal expansion of a fluid in a two-stage chamber 12 is the balance of volume increments caused by thermal expansion. expansion of this fluid aV, as well as thermal expansion of the body on the length of the chambers 12 and 15 liter V, .., and the rod 17 d Vj, ...

(one)

L V, D M - d Vet The change in volume caused by the expansion of the fluid and the elongation of the walls is expressed by the formulas LL-Oimit, respectively. ci nbcoteit--, V is the initial volume. liquids in a two-stage chamber 12; S - square jumper 16; L is the length of the two-stage chamber 12; L is the initial length of the rod 17; A-, LS are the coefficients of thermal expansion of a liquid and a rod material, respectively (linear); At - change in temperature Dg, Ots - diameters, respectively, of the upper (greater) and lower (smaller) stages of the two-stage - chamber 12. The change in capacitance of the two-stage chamber 12, due to the thermal expansion of the chamber body wall, occurs both in the longitudinal (axial and transverse directions. However, the effect of expansion in the transverse direction, as shown by calculations, is negligible compared to the longitudinal elongation the entire length of the camera body, including the length of the two-stage chambers 12 (L | 4,) and an additional 15 (LC). The latter is equal to the length of the stubs 17 (LCJ. Unaccounted for -12 expansion in the transverse direction only improves the and thermal expansion of the fluid in chamber 12. The increase in the volume of chamber 12, due to the elongation of the chamber body, is the product of an area equal to the area of jumper 16 with diameter On, by changing the length of the body - (L + Lc;). t, (4) where the coefficient of thermal expansion (linear) of the material, housing, chambers. Taking into account the expressions (2), (3) and (we obtain from the condition (1) the condition of compensation of the thermal expansion of the liquid in the two-stage chamber in the form

When testing the depth gauge, 96 cm is used as a working fluid.

The length of the camera body is equal to

11 + 96 107 cm. Overall

+ L

65 length of the tested sample of the deepest used olive oil, having a coefficient of thermal expansion equal to 1 - and compressibility factor equal to f, b, 3-10. The camera body is made of duralumin with a linear expansion coefficient of - 2.0-10 - // ° C, and the rod 17 is made of a superinvar with a coefficient of linear thermal expansion equal to с. 0,1510 When calculating the dimensions of the prototype, the following was preset: Length of the upper chamber 12 L 0.5 cm Stroke stroke length 8 LUI 10 cm Rod diameter 8D 0.4 cm The jumper diameter 16 Og 3.0 cm The dimensions of the rod 8 are selected in accordance with rod sizes. The length of the rod, in addition, provides a sufficient length of the record on the chart. A decrease in the capacity of the chamber 12 at full stroke of the rod 8 is,. , .., 5-0.4 .-, V, 26 This decrease is due to the elastic compression of the fluid in chamber 12 under the action of external pressure and therefore the value of d v. attached to the india r. Based on the fact that the increase in the profile in chamber 12 is from 0 to 1000 kgf / cm (kgf / cm), then the required initial volume of the chamber is 20 cm% 6.3. 1000 As indicated, the rod stroke 1c, aven 10 cm. To accommodate this current, chamber 12 must be of a greater length, for example, L 11 cm. Therefore, the inner diameter of the upper stage of the chamber is 12 Aven D, A.-0 | U ° 1, 4 CM I u I ± i, u - i;, j A length of 17 L. can be calculated on the basis of forglula (5), which describes the condition for compensating for thermal expansion of the fluid enclosed in chamber 12, -14-10 -2-10 2 , 00-10- -0.15- 10-5

the pressure gauge is 152 cm with an outer diameter of 3.8 cm.

The proposed depth gauge allows obtaining objective pressure values in the wells by automatically eliminating the effect of thermal expansion of the fluid on the gauge readings.

In the oil industry, the application of the proposed pressure gauge will capture the dynamics of pressure over the years of development and take on the basis of this measures to increase oil recovery; catch pressure changes in the process of deep well exploration, and make these studies practically feasible, which, for its part, will allow to develop sound development projects based on understanding the nature of the changes occurring in the reservoir during the development.

Claims (2)

1 .. Kamenetsky S.T. and others. Oilfield reservoir studies. ., Nedra, 1974, p. 151-153. 2. USSR author's certificate 462020, cl. E 21 B 47/06, 1974 (prototype). t