SU1716118A1 - Method of seam pressure determination based on hole test data - Google Patents

Abstract

This invention relates to the coal industry and can be used. It is designed to determine the reservoir pressure of gas during exploratory drilling of wells from the surface, as well as when drilling measuring wells into the studied formation from adjacent workings. The goal is to increase the reliability of determining reservoir pressure. The bottom line is that they repeatedly create depressions on reservoir 1, followed by recording of recovery curves. After sealing the well, a fixed mass of gas is injected into the well, the steady pressure is measured, then the gas is vented, the measured pressure is measured. Once again, the same mass of gas is injected as in the first case, and the steady-state pressure is recorded. Formation pressure is determined by the formula, which includes the specified values, SL

Description

The invention relates to the coal mining industry and can be used to determine the reservoir gas pressure during exploratory drilling of wells from the surface, as well as when drilling measuring wells into the studied formation from adjacent workings.

The purpose of the invention is to increase the reliability of determining the gas reservoir pressure.

The method is carried out as follows.

A well is drilled from the surface, either from the iverstlag or from a different development along the normal to the formation under study, crossing its full capacity. At the same time, the volume of the volume removed from the well is recorded.

Drilling coal Ush (volume of shtyb). The section of the well traversed in the rock is sealed, and the section traversed in the coal seam, which is a measuring chamber, is connected to the production (or surface) using a thin tube. A pressure gauge is attached to the outer end of the pressure measurement tube, and a microventil and a flow meter are installed to measure the amount of gas entering or flowing out of the well. It is believed that in the natural, undisturbed state, the coal seam does not filter, and the gas is in isolated pores and cracks. After the well has been set up, the microventil is closed, the pressure recovery curve is recorded in the measurement

vi o

00

the camera and record the steady-state pressure R.

As a result of drilling a well in the reservoir, a destroyed zone is formed around it, in which a system of filtration channels (filtration zone) originated.

After the microventilation is closed, the gas enters the measuring chamber only from this zone, and not from the entire reservoir, so that the pressure of the pressure set in the measurement chamber will be significantly lower than the true initial pressure of the gas in the formation.

After the pressure is established in the measuring chamber, a fixed mass of gas А М is pumped through the microventil into the measuring chamber, the value of which is chosen from the condition

AM (0.5-2.0),

where Ush is the volume of coal (shtyb) taken out while drilling, m3.

Next, close the microventil, record the pressure recovery curve and record the steady-state value of pressure R. Open the microventil, allow gas to flow out of the metering chamber, and record the amount of gas flowing out. In this case, the pressure P in the metering chamber is kept constant, choosing it from the condition P (0.7–0.9) P. After the gas mass outflow from the well, the value of which is determined from the condition AMi (1.5-5.0) DM, the microventil is closed, the pressure recovery curve is recorded and the established pressure value P is recorded.

After the pressure P has been established, a mass of gas equal to the DM is injected into the well through the microventil. Then, the microventil is closed, the pressure recovery curve is recorded, and the steady-state pressure P is recorded.

The value of formation pressure is then determined by the formula

GDM1

.one

one

 - 1Cr -

Example. A coal seam with a capacity of h 1 m was re-drilled and sealed with a well of radius, 5. m, while the volume of coal was removed from the well. m3. When drilling and arranging the well, a zone of permeable angles was formed - a filtration zone. Its radius is. After sealing, the pressure was set in the measuring chamber atm.

Pumped into the well a mass of gas (methane) equal to

DM 1.Vu ,, 192 kg

After the pressure in the metering chamber was established, its value was equal to atm. Then the valve was opened and the mass of gas was released from the well, equal to D Mi 2.5 DM 0.48 kg. The pressure in the metering chamber was maintained equal,

atm

When the formation was emptied over time, the size of the zone, the permeable coal increased and became equal to Re.

After the pressure in the measuring chamber was established and became equal to P 41 atm, the mass of gas equal to DM 0.192 kg was pumped in again. Recorded the steady-state value of pressure in the measuring chamber atm and determined the value of the reservoir gas pressure by the formula

ro P +% uf 1 W-- 153.5 atm.

Claims (1)

The Invention Method for Determining Formation Pressure According to Well Testing, Including Sealing a Well, Repeatedly Creating Depression on a Formation, and Recording Pressure Recovery Curves gas DM, bleed the mass of gas AMi, while the pressure in the measuring chamber of the well during the etching is maintained equal to from 0.7 to 0.9 The pressure of the gas in the chamber after sealing, re-pumped into the well a mass of gas D M, and the reservoir pressure is determined by the formula Ro - P + -1 (Pi p4-- Pi F - R P -R G1 DMN1.5-5.0) DM; D, 5-2.0). РЛ / ш / РгТ where Ro is the reservoir pressure, Pa; P is the set value of the gas pressure in the chamber after sealing, MPa; P is the steady-state value of the gas pressure in the chamber after the first injection, Pa; P is the steady state value of the gas pressure in the chamber after bleeding, Pa; pT is the steady-state value of the gas pressure in the chamber after re-injection, Pa; Vuj - the volume of coal (shtyb) m3 taken out while drilling; Rr is a gas constant; K - temperature, K.