SU1470943A1 - Method of determining occurence of geological formations traversed by a well - Google Patents

Abstract

This invention relates to field geophysics. The goal is to improve the performance of the determination. For this, the pipe string is filled by displacing from it the washing fluid injected from the wellhead with clean water to the interval of the geological formation under study. The pressure of pure water in the column at the wellhead is measured. The average specific gravity of the fluid is determined taking into account the corrections for its volumetric temperature expansion. The depth of the intersected borehole geological formations is judged by the difference in measured pressures. This method can be used to accurately determine the depth of the geological formations.

Description

 one

The invention relates to field geophysics, specifically to geophysical methods for determining the location of geological formations.

The purpose of the invention is to increase the productivity of determining the depth of a well intersected by a geological formation.

Practically at all stages of the construction and operation of a well, a string of drill pipes or tubing pipes filled with flushing pipe is lowered into it. The method involves the use of a column pushed into the well as a vessel for the working fluid — pure water, by the pressure drop in which the height of the liquid column and, consequently, the absolute depth of the measuring point are determined.

there is pressure in it. Filling a column of pipes placed in the well with clean water is carried out by injecting it into the wellhead column and displacing the washing liquid from the column to a predetermined study interval. Due to the difference in densities of injected and displaced fluids to keep the injected water in the desired well interval, the wellhead is sealed and simultaneously with the fluid pressure measurement in the studied interval of the column, the fluid pressure in the wellhead is measured. Since the flushing fluid in the annulus of the well exerts pressure on the filling water through the open lower end of the pipe string, the pressure of water in the column at the mouth j

CO i4 CO

boreholes are different from zero, and the height of the water column from the measurement point in the well to the mouth of the skvagigach may be from the ratio of

n Ei-i-Ei, d j, p

where Pj is the pressure in the column at

J Pa studies; Ru water pressure in the column on

wellhead, Pa; .dj.p is the average value of the specific weight of water, drowning the thick column of pipe wells in wells, taking into account the influence of the continuous thermal expansion of the tank, its compressibility and the change in the normal acceleration of gravity at the measuring point, N / m,

The method is realized in the wells with the following sequence of operations.

Pure water is injected into a downhole tubing column (drilled or pump-compressed), for example, for drinking-water purposes up to a predetermined study interval. The volume of water is calculated from the BHyrpeiHiero volume of the filled pipes to the required depth. The wells determine the temperature of the water with an error of ± 0, and its initial density with an error of 0.01%. The water pumped into the pipe string produces: flushes the flushing fluid filling the well and displaces it through the annulus from the well. To reduce the zone of mixed clean water and the flushed flushing fluid between them, a small portion (100-200 liters) of viscous elastic the separator, which is a three-component gel-like mixture with a density of lOOOixr / Mj (d), it is used for well cementing. In this case, a clear boundary is obtained between the water pumped into the skvshkin and the fluid. Water is pumped into the column to the interval where the geological formation under investigation is located, the depth of which is determined. After that, 1 eperm5-1 ziziruyut wellhead. Near the occurrence of the geological formation under investigation by a contactless geophysical method (for example, TC or PHC), I register

Q

h 0

5 0 5 0

0

The benchmark, 13 of which is used as a character of a different plpsi on the curves of the CC | (NGK).

At the point of the geological reference, the pressure of the liquid column in the column is determined by a pressure gauge (for example, Tina-36) with a pressure error of less than 0.1% and the pressure of the liquid I is measured at the wellhead at the same time. no more than 0.01%. For introducing corrections to the change in liquidity with depth, the temperature is determined with an error of +0.1 ° C and pressure with a resolution of +1 atm fluid in Colonel along the wellbore and the average value of the specific gravity of the fluid is determined taking into account corrections for its flow temperature the expansion, compressibility, and changes — the normal acceleration of the force of gravity, Racce, and the amendment, 1; 1, are determined by special programs on the microcomputer or by hand.

Based on the calculations, the height of the liquid column from the wellhead to the point of the geologic reference point is calculated, and, knowing the altitude of the wellhead, the absolute depth of the well and normal and more than 0.12% is determined.

Know gol.niu for .p.gak1 -n geological reference point on the ospovails danny incognog etp1p1 determine the depth of the harravH-iH explored geological formation and, since the geological turnip 20 m), the error in determining the vertical projection of this interval will be negligible,

The proposed method can be with B1-1SOKOY. The depths of the depths of all were determined by the cleanliness (of those who cross the intersecting squambles / geological zone

P1) the proposed method makes it possible to significantly increase the productivity of conducting geophysical surveys of a well in order to determine the depth of the geological formations without reducing the accuracy.

To implement the method in a well, the cinema does not require the development of any new instruments and devices, which will provide it with the possibility of wide application in field research practice, 11.

51A709 36

Claims (1)

The invention of laziness, the pipe string is filled by The method of determining the depth of the room-displacement of the flushing fluid from the geological bones intersected by the well, which is injected from the wellhead formations, containing fill-clean water up to the interval, investigating the leak-tight column into the well, measure the pressure —say the wellhead, measure the length of the wellbore and determine the amount of pure water in the column at the mouth of the average specific gravity of the water in the wells, and about the depth of the well, i.e. zhinoy geological for- chayuschiys that, with tselyumatsy judged by the difference izmerenngh enhance performance-determined pressure.