SU1018085A1 - Geological structure locating method - Google Patents

Description

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The invention relates to exploration geophysics and can be used when conducting a search for geological structures on the shelf of the seas by the method of geometric exploration.

There is a known method of searching for geological structures by a geothermal method, which includes temperature measurements) at a depth of at least 20-25 m, where annual temperature fluctuations practically fade out Hi.,

The disadvantage of this method is the need for a large amount of dead drilling operations.

The closest in technical essence to the invention is a method for searching geological structures, including drilling wells and measuring the temperature of rocks in them at depths equal to 0.23-0.30 in thickness of the layer with varying annual temperatures fZ.

A disadvantage of the known method is that when conducting a search for geological structures on the shelves, the use of this depth interval for temperature measurements requires large amounts of drilling.

The purpose of the invention is to reduce the volume of drilling during geothermal research on the shelf.

The goal is achieved by the fact that, according to the method of searching geological structures, including drilling, the temperature of rocks in them is measured and their abnormal values are judged on the presence of structures, the temperature of bottom sediments is measured at depths of 0.09-0.13 layer thicknesses with varying annual temperatures.

The method is based on the following laws. The upper limit of the depths of this interval is limited by the attenuation depth of the daily amplitudes of temperature fluctuations on the shelf, which at the depth of the sensor should be less than 0.01 ° C. According to calculations and data from experimental observations, the decay level of daily temperature fluctuations in bottom sediments is 0.09 layer size with varying annual temperatures. This level is not reached by other temperature interferences associated with short-period quasiperiodic oscillations. The lower limit of the depths of the interval is determined by the greatest contrast of the thermal diffusivity of lithological

TYPES of bottom sediments of the shelf combined with the minimum allowable depth of the sea at the observation points and is 0.13 layer sizes with varying annual temperatures from the bottom surface. The indicated depth interval is universal for different seas, oceans and climatic conditions.

The method is implemented as follows.

In the surveyed area of the shelf, a reference point with the minimum sea depth and the type of bottom sediments with the lowest thermal diffusivity coefficient is selected using the navigation and earth maps. For this item, by the known thickness of the water layer, the determined T is the depth of the bottom of the layer with varying annual temperatures. Then, in the reference point, the required immersion depth of the Temperature Sensor is calculated to be 0.09 of the layer size with varying annual temperatures. At the reference point and all points of interest in the area under study, the depth of the sea is determined from a navigation map or by echo sounder measurements. For all these points, using the soil map or, taking cores of bottom sediments, determine the lithologic type of sediments and determine their thermal diffusivity, which is measured experimentally using the method of instantaneous linear heat source or choose the average for the corresponding lithological type of bottom sediments using the reference bottom. Further, for each observation point, the desired depth of immersion of the temperature sensor is calculated taking into account the depth of the sea and the lithology of bottom sediments using the formula H

h .0, OZNE. 1 N where Hj is the depth of the sea in the reference point: кте; I. depth of the sea at the point of observation;

thickness of the layer with varying N with annual temperatures; temperature coefficient of bottom sediment waterfall in the reference point; a is the thermal diffusivity of bottom sediments at the observation point. Then, using the technique and equipment of marine geothermal survey.

310180854

The temperature is measured in points of the area. Using the bottom method at a given depth (T), this shelf eliminates distorted measurements, makes geotemperatives from external temperature waves and a one-way area map. Timely reduce the cost of drilling

Claims (1)

METHOD FOR SEARCHING GEOLOGICAL STRUCTURES, including drilling wells, measuring rock temperature in them and judging by their abnormal values about the presence of structures, which means that, in order to reduce drilling volumes during geothermal studies on the shelf, the temperature of the bottom precipitation is measured at depths equal to 0.09 0.13 thickness of the layer with varying annual temperatures.