SU1624141A1 - Method of locating productive intervals in oil pools - Google Patents

Abstract

The invention relates to the downhole development of oil fields. The purpose of the invention is to improve the accuracy of determining the productive intervals of uncased formations due to the stratification of the measured flow rate 1 p. Before the inflow of formation fluid is called up, the wellbore in the test interval is filled with a fluid that is not miscible with oil. The determination of the productive intervals is made according to the measurement of the fluid's physical characteristics with the influx of formation fluid in the well. In the study of the flow rate of NRPTI and the density is not miscible with - (the liquid eft (pp) meets the condition qMCI№ qMV, 4 + 2 (pp / pH-i), 1De q / MUH, qMa "- the minimum and maximum values of the flow rate per 1 m the top of the product intervals, which ensure the stratification of the fluid flow in the well (t 1 m / day); Pi - the density of oil in reservoir conditions. To maintain stratification of the fluid flow at the time of measuring its physical characteristics, the wellbore is equipped with a perforated shank. f-ly, 2 ill. S (L

Description

The invention relates to the well development of mineral oil fields with porous-fractured reservoirs that do not contain water.

The purpose of the invention is to improve the accuracy of determining the productive intervals of uncased formations due to the stratification of the measured fluid flow.

Figure 1 shows the results of thermometry, flow measurement and moisture measurement in a well; figure 2 - the results of thermometry, flow measurement, moisture measurement and density measurement.

The method is carried out as follows.

Before examining the well bore in the non-core portion, pour heavy, oil-immiscible oil with a density greater than the density of the oil. Then, a bespakerny debitometer is lowered to the bottom of the well, and the well is put into operation with a flow rate that does not violate dynamic stratification. At the same time, the density of a liquid that is not miscible with oil and the flow rate per 1 m of the thickness of the working layers are chosen in accordance with the condition

VCIKC

RR

+ 2 (K - °

where QMYW P liax corresponds to the minimum and maximum flow rate per 1 m thickness of the productive intervals that ensure the stratification of the fluid flow (FR, PI 1 m3 / day); Pp, RY, respectively, the density of a fluid and oil that does not mix with oil under reservoir conditions.

The allocation of working oil intervals is as follows.

Depending on the location of the device, we consider 3 cases:

 The instrument (flow meter, density meter or moisture meter) is below the lower oil interbed. In this case, there is liquid in the sensitive part of the device pumped into the well, its physical characteristics are recorded by the device}

the device is located opposite the oil interbed. The oil flows from this interbed have a velocity component that is perpendicular to the direction of the instrument, which allows the oil to enter its sensitive part, displacing the liquid there. In this case, the physical parameters of the oil are recorded;

the device is located above the oil spill. Oil is bubbled through the fluid column along the wellbore, parallel to the direction of movement of the instrument, not passing through its sensitive part. In this case, the physical properties of the injected fluid are recorded.

Due to the dynamic stratification to isolate interlayers, not only a debitometer can be used, but also a moisture meter and a density meter, which were not used to improve the reliability of reservoir formation. These devices can be used consistently. To do this, in the working well, the diagrams of the mechanical debitometer, densitometer and moisture meter are taken. At steady-state filtration mode, the boundaries of the inflow intervals from the reservoir correspond to the boundaries of the mixture density variation on the density meter diagrams that correspond to the boundaries of the dielectric constant in the moisture meter diagram. In the mechanical debitometer, the lower limit of the working interval is beaten off at the beginning of an abrupt change in the speed of the turntable in the direction of increasing readings, and the upper limit is beaten off by a sharp decrease in the speed of its rotation.

When using devices that allow a part of the flow through internal channels, stratification of the stratified state or loss of its stability with complete mixing of two liquids are possible. This is usually observed with a sharp difference in the thickness of two adjacent layers of oil or the productivity of the respective interlayers. In order to increase the reliability of the method in these conditions by eliminating the violation, the perforated liner is lowered into the well to disrupt the stratification before the heavy liquid is poured.

The diameter of the perforated shank should be taken into account. The diameter of the shank should be so commensurate with the diameter of the device so that there are water-oil jumpers inside it at non-operating intervals when the device is moving or that the device does not force the liquid out of the shank when lifting. In this case, in the study interval, the main output fluid flow moves between the walls of the well and the shank. Inside the shank, the layers are separated into oil - liquid against working intervals and liquid - oil against non-working intervals.

Example 1 A formation was investigated in the range of 2754-2775 m. A CsCl-solution with a density of 1.28 g / cm was used as a working fluid that is not miscible with oil. The density of oil is 0.7 g / cm. The flow rate was 24 m / day. The working thickness of the reservoir is 15.4 m. Thus, the flow rate was 1.4 m / day for 1 m of the working thickness of the formation. Differentiation in density of 1, 8 times at a debit of 1.4 mea / day per meter of working thickness of the layer provides stratification of the measured fluid flow. The well was examined by a mechanical flowmeter. An experienced highly sensitive thermometer was used for comparison. The debitometer was used to make two recordings: the main and the control (second by points). The well was equipped with a 2.5-inch shank suspended on lift pipes

The interpretation diagram for debitometry and thermometry is shown in FIG. 1. The allocated productive intervals are indicated by the sign in the column of inflow intervals. The interval points selected according to the reading of the flow meter are confirmed by the thermometric method.

Example 2. A well is equipped with a 4-inch shank in the open hole interval, suspended on elevator 2.5-inch pipes. The slaughter is filled with a CaCl solution with a density of 1.07 g / cm. The density of oil is 0.7 g / cm. Differentiation in density by 1.5 times. The well was investigated by mechanical flow rate in February with a flow rate of 42 m / day at 22 m working thickness. Thus, the flow rate was 1.9 m3 / day per 1 m working thickness. With a differentiation in density of 1.5 times and a yield equal to 1.9 m / day per meter of working thickness, stratification is provided (FIG. 2),

Further, the well was investigated by the method of moisture measurement and thermometry. In this case, the flow rate was 30 m / cy at 22 m working thickness. The flow rate was Ј.1.4 per 1 m of working reservoir, with the same differentiation of densities 1.5 times the stratification was ensured.

As can be seen in FIG. 2, the boundaries of the main operating inflow intervals fully correspond to each other in all the diagrams. The selected intervals are indicated by a sign in the column of inflow intervals in Figure 2. The method allows to reliably distinguish productive intervals in cased,

and in uncased wells in the collectors of the granular, fractured and fractured type. This method allows the use of instruments such as a density meter and a moisture meter to isolate oil inflows.

Claims (1)

1. A method for determining productive intervals in oil reservoirs, including invoking the inflow of formation fluid into the well and determining the productive intervals according to the measurement of the physical characteristics of the fluid along the axis of the wellbore, characterized in that, in order to improve the accuracy of determining productive intervals of the open casing due to stratification the measured fluid flow, the wellbore in the interval under study, prior to the call of the inflow of formation fluid, is filled with a fluid that is not miscible with oil, and the measurements of the physical their fluid characteristics are carried out at an oil production rate and the density of a liquid not miscible with oil that meets the condition RR Max ™ + 2 T 1} where Chmeee and chm ks are the minimum and maximum values of flow rate, respectively, a 1 m thick j. productive intervals, ensuring an fluid flow stratification (MJ / CYT), m Vcyr; i is, respectively, the density of a liquid and oil that is not miscible with oil in reservoir conditions, g / cm, 2, the method of claim 1, dated 1 and 2, and the fact that the physical characteristics of the fluid flow are measured in a wellbore equipped with a perforated shank. ri p (