RU2104395C1 - Method for determining level in pipes - Google Patents

Abstract

FIELD: oil and gas production industry. SUBSTANCE: this is intended for investigation of oil and gas well in process of drilling. According to method, determined in pipes in testing of well is level raising through bed tester. Subcritical flow of gas is measured by membrane instrument. Rate of air flow discharged from pipes and absolute initial pressure in them in mm Water column, also moment of membrane closing and time period of pressure raising in pipes to final value are measured by stop watch and aneroid barometer. Calculated value of changing volume of empty pipes as product of air flow rate multiplied by membrane closing period as determined according to Boyle's - Mariotte's law constitutes initial volume of empty pipes, and through dividing this value by specific volume of pipes determined is sought for level in them. EFFECT: higher efficiency.

Description

 The invention relates to the testing and testing of oil and gas wells during drilling.

 On December 14, 1992, the Gosgortekhnadzor of the Russian Federation approved the "Safety Rules in the Oil and Gas Industry" (M.: 1993, NPO, MBT), where the section "Well Research by Pipe Testers" (IPT) indicates that the test is carried out without the release of topping fluid or formation fluid to the surface with the maximum possible depression in a two-cycle mode; The technology of testing an object with the release of formation fluid to the surface is used when re-launching an IPT to assess the industrial significance of a gas and oil-saturated formation.

 Thus, the question of assessing the industrial significance of the reservoir during the drilling process before the launch of the production string has been raised.

 Obviously, a negative assessment of the industrial significance of the reservoir and well can only be given in case of a weak fluid flow.

 The industrial significance of the well and the field depends on many factors, including geographic location.

 A known method for assessing the industrial prospects of the tested objects when obtaining lowering pressure values at the end of closed periods in two- and three-cycle tests [2]. Two- and three-cycle tests make it possible to more confidently assess the industrial prospects of productive horizons, i.e., those that are evaluated as oil and gas saturated by the test results. It is practically very difficult to agree to refuse the test in the column of an object that has proved to be productive when tested in an open trunk. This requires irrefutable data on the futility of such an object. Along with this, it is difficult to agree on the necessity of lowering the production casing to the facility, which, although it produced products, has a tendency to steadily lower the pressure as fluid is taken from it.

 Thus, it is important to properly and thoroughly organize an open-hole test, to achieve the final result.

 An example of testing Mineral 4 Mineral in the interval 5228-5288 m is described: 1st open period 10 min; 1st closed period 40 min; 2nd open period 60 min; 2nd closed period 130 min.

 The level in the pipes increased by 140 m, associated petroleum gas was taken. The difference between the pressure values at the end of the first and second closed periods was 6.3 MPa. The extrapolation of the pressure curves yielded two reservoir pressure values of 82.7 and 77.2 MPa, the skin effect turned out to be 3.07 and 4.4, respectively, which indicates that the bottom-hole zone is not contaminated. The “kink” of the Horner graph (for the second HPC) indicates that the permeability of the remote zone of the formation is even lower than the permeability of the zone. Assigning a layer to the test in the column is clearly impractical.

 An example of a test of well 253 Oktyabrskaya in the interval 4895-4896 m is also described.

After a repeated (08/17/76) three-cycle pressure test at the end of the first and second closed periods (61.8 and 58.8 MPa), they turned out to be almost the same as during the first test. At the end of the third closed period, the pressure turned out to be equal to 53.6 MPa. The total duration of the test was almost 15.5 hours. Due to the influx of gas with oil, the volume of liquid from the hopper pipes increased by 3.5 m ³ . Based on the results of two tests, it was possible to conclude that foraminifer deposits in well 253 are productive, but the size of the permeable section of the trunk is limited; the reservoir, although it has a supply area with an initial pressure of 62 MPa, is rapidly depleted and therefore of no industrial value. It should be added that after further deepening of this well and opening of the Upper Cretaceous deposits, when testing the latter, a similar picture was found. Even after repeated acid treatments, the formations worked with a decaying flow rate. Thus, the strata worked with a decaying flow rate and the Upper Cretaceous deposits had a limited permeable area, which quickly depleted when oil was taken from it.

 Currently, the prior art does not allow to raise the question of the negative industrial significance of the formation when it is tested once by the pipe formation tester (IPT).

 The proposed method for calculating the level in pipes should allow solving this problem in one run of IPT.

 The washer meter for subcritical gas flow has been known for a long time (in particular, see V.M. Muravyov, “The Master's Guide to Oil Production,” Moscow: Nedra, 1975, p. 189).

,
где d - диаметр отверстия шайбы в мм;
H - высота столба воды в образном манометре, мм;
T - температура газа, K;
ρ - относительная плотность газа по воздуху.To determine the gas flow rate, the following formula is used:

,
where d is the diameter of the washer hole in mm;
H is the height of the water column in the shaped pressure gauge, mm;
T is the gas temperature, K;
ρ is the relative density of the gas through the air.

 The simplicity of this device allows it to be made in repair shops.

 Two measurements were made in Belarus.

 Measurement of gas flow from well N 2 of the East Pervomaiskaya area on February 10, 1970: perforation interval 4142-4153 m; the level in the well is repelled at a depth of 2232 m.

где T принято равным 293 K, относительная плотность газа по воздуху принята 1,2.The measurement was made with a washer meter for subcritical gas flow. The debit is calculated by the formula

where T is taken equal to 293 K, the relative density of gas through the air is assumed to be 1.2.

Расход газа из насосно-компрессорных труб (НКТ)

С 5 по 10 февраля средний подъем уровня 12 м/сут, что соответствует притоку жидкости в 145 л/сут или 0,145 м³/сут.Gas flow from the annulus

Gas flow from tubing (tubing)

From February 5 to 10, the average level rise is 12 m / day, which corresponds to a fluid influx of 145 l / day or 0.145 m ³ / day.

Gas factor
(13.1 + 0.635): 0.145 = 13.735: 0.145 = 95 m ³ / m ³ .

 Measurement of gas flow from well N 72 of Rechitsa Square. With closed tubing, the pressure in them increases by 20 mm of water. Art. for 5 min or 240 mm of water. st / h Annulus closed.

During the measurement, the position of the level remains almost unchanged and remains at a depth of 1009 m according to the level beating. The volume of tubing is considered constant and equal
0.785 • 0.403 ² • 10 • 1009 = 1.275 • 1009 = 1290 l.

 The initial pressure at the mouth will be equal to atmospheric or 10300 mm of water. Art.

The pressure increment in the tubing for 1 h is
240: 10300 = 0.0233 part.

The hourly inflow of water and gas into the tubing is 0.0233 part of the volume of empty tubing or 0.0233 • 1290 = 30 l / h (0.72 nm ³ / day).

The influx of liquid (water) into the well by measurement with a deep winch and a float of 0.093 m ³ / day.

The calculated gas factor
0.72: 0.093 = 7.75 m ³ / m ³ .

 The above calculations were performed in 1970. We apply the Boyle-Marriott law to the last example with some error due to the additional supply of a small amount of gas in the wasteland.

We introduce the following notation:
V ₁ - the initial volume of empty pipes (in the example of tubing);
V ₂ - the end of the volume at the end of the measurement with the washer closed;
P ₀ - atmospheric (barometric) pressure, mm of water. st .;
P ₁ - initial absolute pressure in front of the washer;
P ₂ - the final absolute pressure before the buried washer;
t is the measurement time with the washer closed;
ΔV is the total amount of liquid and gas received in the tubing during the measurement time t;
Q - air (gas) flow rate measured by the device.

 Obviously, ΔV = Q • t.

 Conventionally, we assume that gas (air) in empty tubing was compressed by the ΔV volume due to a rise in the liquid level in them.

In this case, V ₂ = V ₁ -ΔV, q is the volume of 1 linear. m tubing, in the example of 1,275 l / m

By Boyle-Marriott Law
P ₁ • V ₁ = P ₂ V ₂ ; P ₁ • V ₁ = P ₂ (V ₁ -ΔV); V ₁ (P ₂ -P ₁ ) = P ₂ • ΔV.

,
где L - длина пустых труб или уровень в них определяется уравнением

.The initial volume from the last equation

,
where L is the length of the empty pipes or the level in them is determined by the equation

.

In the last example, ΔV = 30 l at t = 1 h. Absolute pressures P ₁ and P ₂ are equal to atmospheric (barometric) pressure plus readout on a U-shaped manometer H _b (mm. Water. Art.).

 Atmospheric pressure and equal to 10300 mm of water. Art.

P ₁ = 10300 mm of water. Art., gas flowed freely from the tubing to their closure.

P ₂ = 10300 + 240 = 10540 mm of water. Art. by measuring pressure growth.

P ₂ -P ₁ = 240 mm of water. Art.

.Empty tubing length

.

 The actual level with a deep winch and a float is repulsed at a depth of 1009 m.

.Measurement error 1035-1009 = 26 m or

.

 A similar error is permissible when testing (testing) IPT wells, especially in the case of weak fluid inflows. With an intensive inflow of produced water, a static level can be established in 30-40 minutes, from which dissolved gas will continue to be released.

 Having established this fact by the proposed method, it is possible to apply an informed decision on the further conduct of the testing (testing) process.

 The test is carried out without the release of liquid topping up on the surface with the maximum possible depression in a two-cycle mode (see. "Safety rules in the oil and gas industry).

The requirements for testing without the release of fluid and the maximum possible depression are fully justified, and the requirement of a two-cycle regime cannot be considered justified. It should be noted that the number of cycles is not related to work safety. The number of test cycles of IPT wells depends on the intensity of fluid inflow. In the case of intense inflow, one cycle is sufficient. The speed of air flow from drill pipes with IPT depends not only on the rate of rise of the dynamic level, but also on the gas factor, which varies from 10 to 100 m ³ per 1 m ^{3 of} fluid.

 To date, there is no acceptable way to determine the level in drill pipes when working with IPT.

 The present invention provides such a method.

 The closest analogs are acoustic equamers (Vasilevsky VN, Petrov AI "Technique and technology for determining the parameters of wells and reservoirs." M .: "Nedra", 1989, p. 180). However, they are based on another principle: when measuring the level by the acoustic method, an acoustic pulse is sent to the annulus of the well, created by the explosion of the powder charge at the mouth. After some time, the arrival of a pulse reflected from the surface of the fluid in the well is noted on the surface using a sensitive device.

 The specified method was used in NGDU "Rechitsaneft". The impulse was first created by closing the annulus with the U-shaped pressure gauge attached to it with water and opening it for a short time and closing it. The arrival of the pulse was recorded by the fluctuation of water in the tubes of the pressure gauge. The time was fixed by a stopwatch, which was turned on when the annulus was opened and turned off when the levels in the manometer fluctuated.

 The measured time (s) was multiplied by 160 m / s. The results obtained satisfied the practical requirements for determining the level in the annulus during the operation of wells by electric submersible pumps. The known and proposed method has allowed to abandon the use of an echo sounder.

 The reasons that prevent the measurement of levels in drill pipes with IPT, is the complication of work on testing (testing) wells IPT.

 The level rise in the drill pipes is fixed by the depth gauges installed in them.

 The objective of the invention is the measurement of levels in the pipes in the process of testing (testing) wells IPT with the aim of operational solutions for open and closed periods.

 In order to determine the rising level of fluid in the drill pipes due to the influx of fluid through the IPT, the following actions are performed.

1. Atmospheric pressure P _{0 is} measured with an aneroid barometer and converted to mm of water. Art.

 2. According to the inner diameter of the pipes specify the volume of 1 linear. m them q.

3. The washer meter measures the air flow from the pipes Q at the largest aperture of the washer and the lowest pressure H ₁ . Recalculate the pressure in absolute P ₁ = P ₀ + H ₁ , mm water. Art.

4. Close the washer hole until the pressure rises to 200-250 mm of water. Art., and stopwatch measure the time of pressure rise to the final H ₂ , recount it to the absolute pressure P ₂ = P ₀ + H ₂ , mm water. Art.

м.5. Determine the length of the empty pipes (level) by the formula

m

If Q • t = ΔV is defined in m ³ , then q is expressed in m ³ per 1 running meter. m

 The main technical result is expressed in the fact that the testing process can be carried out depending on the work of the formation and get enough material in one run of IPT to unambiguously evaluate the industrial significance of the formation.

 Comparing the rate of rise of the level in the pipes with the rate of outflow of air from them, it is possible to evaluate oil or the reservoir inlet from the gas factor.

 It can be noted that when determining the rate of level rise, the error of one sign associated with the deviation from the Boyle-Mariotte law is compensated.

 With a weak inflow of produced water, the task of taking its submitted sample comes to the fore. To this end, the open period is maximized by reducing the closed period.

 With a weak oil inflow through several cycles, they try to flush the bottomhole zone and get enough material to assess the industrial significance of the formation.

 In case of intensive inflow, they are limited to one cycle.

 Information confirming the possibility of carrying out the invention: a washer meter with a U-shaped pressure gauge for it can be manufactured in a mechanical workshop. The pressure gauge tubes are made of transparent plastic tubes. The washer gauge was attached to the standard cement thread with a non-standard union nut, which did not ensure the tightness of the connection. The washer meter is equipped with a standard union nut. A stopwatch is available at the rig. Measurement of atmospheric pressure is not difficult, with sufficient accuracy it can be used from a weather report.

Сопоставляя скорость подъема уровня в трубах со скоростью истечения воздуха из них, по газовому фактору оценивают, что проникает в трубы - нефть или пластовая вода.Empty drill pipe length

Comparing the rate of rise of the level in the pipes with the rate of outflow of air from them, it is estimated by the gas factor what penetrates the pipes - oil or formation water.

 Depending on this, the number and duration of open and closed periods is prescribed in order to obtain sufficient information to assess the industrial significance of the formation in one IPT run.

Claims (1)

 A method for determining the level in pipes rising through the formation tester during testing (testing) of the well, characterized in that the washer meter of the subcritical gas flow, stopwatch and aneroid barometer measure the air flow from the pipes and the absolute initial pressure in them in mm of water. Art. close the washer and measure the time the pressure rises in the pipes to the final value and, calculating the change in the volume of empty pipes as the product of air flow by the time the washer was closed, according to the Boyle-Mariotte law, determine the initial volume of empty pipes, dividing them by their specific volume, determine the level in pipes.