SU870688A1 - Method of determining seam pressure - Google Patents

Description

(54) METHOD. DETERMINATION OF PLASTIC PRESSURE

FIELD OF THE INVENTION The invention relates to the oil industry, in particular to the operational determination of reservoir pressures in the course of exploration drilling under AHRF conditions. The known method for determining the reservoir pressure gradient, in which in the immediate vicinity of the bottomhole, the well is washed in several stationary modes of operation of the mud pump, the mud flow rate, gas concentration in it, and the pressure in the well SP are measured. This method has the disadvantage that in the case of simultaneous gas injection of several previously opened formations, the accuracy of determining formation pressure decreases sharply, or the determination of formation pressure becomes impossible. Methods are known for determining plate pressures using packer pressures separately for each formation 2. These methods do not allow simultaneous sampling from different depths in the well. There is also a known method of testing several horizons in one descent of the GZ tool. This method also has a number of disadvantages. It is impossible to measure reservoir pressures in all gas streams of the lean strata: if there are cavities in the walls of the open hole C, due to the impossibility of packer); in an open hole with a different (stepped) diameter, in cases when, during the testing of the first formations, the packing element is damaged, in ultra-deep wells with abnormally high temperatures (the material of the rubber sealing element loses elasticity). In addition, the method of testing several objects in one trip requires the use of complex test tools. The goal of acceleration is to accelerate the determination of reservoir pressure. This goal is achieved due to the fact that in the process of drilling a borehole at the bottomhole, deep mud samples at each of the stationary modes of operation of pumps from different depths of the annulus are sampled simultaneously and pressure is measured at depths of sampling. At all sampling depths, the pressure in the annular space of the well is measured continuously. The sequence of operations in the implementation of the method is as follows. Down the drill pipe to the bottom with installed at each of several levels from the lower end of the drill pipe through a set of depth gauges, consisting of a depth gauge and several depth samplers. The number of samplers at each depth should be equal to the number of selectable modes of washing. Flushing of wells at several stationary modes of pump operation is performed and at each mode deep drilling fluid samples are taken at the same time (with a time difference of no more than 10 minutes) from all depths of the instruments. Depth samplers are triggered by installing commercially available clockwork mechanisms or by introducing a freely falling fluid into a drill pipe, such as a metal ball, which passes through all the installation depths of the instruments and actuates the existing software mechanism. If clock mechanisms are used, they are set on the surface to operate for a strictly certain time according to the program for changing the rinsing modes in time so that upon reaching the stationary state of each mode rinsing at all depths, sampling would occur simultaneously drilling mud. After flushing in all planned modes and sampling, the drill pipes raise and measure the gas concentration in the deep. Bean samples of drilling mud. In a further known way (see Instructions, on a comprehensive study of gas and gas condensate wells. Under the general editorship of YP Korotaev, GA Zotov and ES Iliva. M., Nedra, 1971, p. . 23) when constructing graphs of gas flow rate versus pressure value, in the second degree, the reservoir pressure of each gas-producing interval is found. Then, gradients of reservoir pressure are determined, a graph is plotted and extrapolated to a predetermined depth. The advantage of this method over the known ones is that when carrying out flushing at the same depth it is possible to determine reservoir pressures along the open interval where there are gas-induced horizons, while reducing the time for carrying out these works to 20%. Improving the accuracy of determining the reservoir pressure in the implementation of the proposed method can be achieved due to the fact that sampling is performed simultaneously under uniform stationary thermobaric conditions due to the immobility of the drill pipe during the entire flushing time period in several modes. When using this method, it must be borne in mind that when applying a lightweight drilling mud, in the process of sampling, it is necessary to take precautions against the open flow. Save time on the implementation of a single reservoir and glisten forecast up to 20% compared with the known methods. Taking the time spent on measuring the formation pressure by the layer tester at three different depths of about 50 hours, we get a time saving of 50 0.2 10 hours. The outcome of the cost of mechanical drilling is 66 rubles per hour, the economic effect in terms of money per forecast is 66 10 660 rubles. . If we consider that in one well the number of required forecasts usually exceeds 10, then the cost savings per well will be at least 6,600 rubles. Formula , a curve of change in the gradient of reservoir pressure is constructed, distinguished by the fact that, in order to accelerate the determination of reservoir pressure, sampling at each mode of operation of the mud pumps is performed simultaneously about all depths, the end position nizhiHero drill pipes stored constant - depth below the highest selection mud samples.

Sources of information taken into account in the examination

1. Cheremisinov OA, Determination of reservoir pressures during drilling. Express information Geologists, drilling and development of gas fields. M., VNIIEGazprom, 14 ,. 1978

2. Yasashin A.M. and others. Test 1teli. seams. M., 1973.

3.Sitdykov G.A. and others. Testing of several objects in one tool flight into the well. M., Nedra, Oil refinery, 1978, W 5,

with. 24-26 (prototype).

Claims (1)

Claim 55 A method for determining reservoir pressure, including flushing a well with lightweight drilling fluid through drill pipes at several stationary pump operating conditions, in which mud samples are taken from a number of depths and gas concentration is measured in them, mud flow rate and pressure in the well are measured, and a change curve is built reservoir pressure gradient, characterized in that, in order to accelerate formation pressure determination, sampling at each operating mode of mud pumps is carried out simultaneously from all bin, while the position of the lower end of the drill pipe is kept constant - below the largest depth of sampling of the drilling fluid.