SU1346775A1 - Method and apparatus for measuring saturation pressure of formation fluid - Google Patents

Abstract

The invention relates to the oil industry and m. used in the exploration and exploitation of oil fields. The invention is an improvement in the accuracy of determination by controlling the sample compression process and ensuring control over the pressure increase in the sampling chamber. When testing a well while drilling, the formation is isolated from the wellbore. They create a depression in the reservoir and cause an influx from it. Before closing the flow-through zone, the reservoir fluid is withdrawn into the sampling chamber 1 (PC). The compressed fluid sample is compressed in the PC when the well was closed and recovered (L 00 О5 vj ate

Description

bottomhole pressure at a rate lower than the bottomhole pressure recovery rate. The pressure charts in the PC are recorded with the inflow and the pressure recovery in it. From the jump in the pressure recovery curve in the PC, the pressure of the phase transition of a two-phase formation fluid to a single phase is determined, the value of which is taken to be equal to the saturation pressure

one

The invention relates to the oil industry, relates to the determination of the physical parameters of a fluid under well conditions and can be used in the exploration and exploitation of oil fields. I

The aim of the invention is to improve the accuracy of determining the pressure of all of the reservoir fluid by controlling the process of compressing the sample and controlling the growth of pressure in the sampling chamber.

FIG. 1 shows a sampling device in the test equipment layout in the well; in fig. 2 - sampling device, general view; in fig. 3 is the same with the pressure distribution during the well test; in fig. 4 is a diagram of the pressure in the sampling chamber at the inflow (KP) and the pressure recovery in it (HPC). I

The method of determining the saturation fluid pressure of the reservoir fluid is implemented using a sampling device (PU) (Fig. 1-3). The device (FIG. 2) is a sampling chamber 1 located in the flow-through zone and placed in the body of the sampler 2. In the sampling chamber 1 a floating unit 3 is installed, which interacts with the hydraulic time relay 4. A pressure gauge 5 is installed in the gauge view to record the pressure change in the sampling chamber.

The device works as follows.

reservoir fluid. To implement the method, a device is used containing a floating piston 3 placed in PC 1, a hydraulic time relay 4 and a pressure gauge in the form of man meters 5. With the help of a piston 3, the sample is compressed in PC 1 and it interacts with the relay 4 and moves in the inner cavity PC 1 along the axis. 2 sec. f-ly, 4 ill.

In the layout of the test equipment, the device is located above the PC packer above the formation tester.

(PI) (Fig. 1). Equipment unloading to the bottom of the well communicates the under-packer space with the internal cavity of the drill pipe. To cause an influx from the reservoir, create a depression

which provides a reduction in bottomhole pressure below the saturation pressure of the formation fluid. At the same time, through the system of holes (Fig. 2) a gas-liquid mixture enters the pipes, the composition of which depends on the size of the depression created on the bed. A pressure gauge 5 installed in the sampling chamber 1 captures the inflow curve (CP) (FIG. 4). By vertical movement of the drill string, the well is closed to record the pressure build-up. When this occurs, the cut-off of the reservoir fluid in the sampling chamber. After the well is closed, the restoration of the bottomhole pressure causes the piston 3 in the sampling chamber to move upwards and the sample to be compressed, since the pressure above the piston is lower than the bottomhole pressure (Fig. 3). A pressure gauge 5 shows the increase in pressure in the chamber (Fig. 4) while the bottomhole pressure Pj and pressure in chamber P are equal. In this case, the compression of the sample by the movable powder occurs at a speed lower than the rate of recovery of the bottomhole pressure, because the rim is connected to the sub-packer zone via a hydraulic time relay, which provides a delay in the recovery of pressure in the sampling chamber. Accommodation meter

pressure in the sampling chamber makes it possible to control the pressure change in the chamber P.

Thus, the presence of these elements (a floating piston that interacts with a hydraulic time relay and a pressure meter placed in the sampling chamber) makes it possible to determine with sufficient accuracy the pressure of the phase transition of the gas-liquid mixture in chamber 1.

In the sampling chamber when the piston moves up, the following occurs. Due to the increased compressible tee two-phase gas-liquid mixture and the rate of pressure recovery in the sampling chamber is somewhat slower. When a gas is completely dissolved in a liquid, a pressure jump occurs at the QED, corresponding to the phase transition of a two-phase formation fluid to a single-phase one (Fig. A). The phase transition point, marked on the HPC, corresponds to the saturation pressure P of the reservoir fluid with gas under downhole conditions. This process can be controlled by comparing the pressure recovery diagrams in the sampling chamber and at the bottom of the well (Fig. 4, dashed line). In this example, it can be seen that the gas does indeed dissolve in the chamber, the saturation pressure of which is 16 MPa.

The accuracy of the measurement is ensured by the fact that the oil-and-gas mixture near the pressure, which is in the metastable state, has an anomalous change in the compressibility factor of the mixture. The compressibility of oil and gas solutions in the pressure region adjacent to the pressure of the pressure increases two or more times (compared with the neighboring region). Therefore, the pressure of the phase transition of the mixture to the single-phase state is clearly recorded on the form of the depth gauge in the form of a jump.

The oil saturation pressure of gas is one of the most important parameters required for the calculation of reserves and the design of oil reservoir development. Development of media births with a bottomhole pressure below the saturation pressure complicates the production of oil and

Claims (2)

1. A method for determining the saturation fluid reservoir pressure when testing a well during drilling, including isolating the formation from the squaline fluid, creating a depression to the formation and causing influx from the formation, withdrawing formation fluid to the sampling chamber and changing the pressure in it, that, in order to increase the accuracy of determination by controlling the process of compressing the sample and ensuring control over the growth of pressure in the sampling chamber, the selection of formation fluid is performed before closing the flow-through zone; The sampled reservoir fluid in the sampling chamber when the well was closed was restored by bottomhole pressure at a rate less than the bottomhole pressure recovery rate, and the phase transition pressure was determined by the flow rate and pressure recovery in the sampling chamber. two-phase reservoir fluid in a single-phase, the value of which is equal to the saturation pressure of the reservoir fluid. 2. A device for determining the pressure on the formation of a formation fluid, including a sampling chamber installed in the flow zone, with a floating piston and a hydraulic time relay, characterized in that it is equipped with a pressure gauge installed in the sampling chamber, and the floating piston interoperability with a hydraulic time relay and axial movement through the internal cavity of the sampling chamber. PU PC 1 R, MPa Rnas-WMna south 5-0 2 FIG. five VSHB About 0.5 10 r, Order 5103/31 Circulation 532 Random polygons pr-tne, Uzhgorod, Subscription