METHOD OF PERMAFROST ROCK BEDDING DELIMITATION Russian patent published in 2008 - IPC E21B36/00 E21B47/06 

FIELD: mining.

SUBSTANCE: invention refers to gas and oil industry and can be used, in particular, to select technology of well building and construction, as well as to monitor technical condition thereof inside permafrost rocks (PFR) and in permafrost zone. According to proposed method, a well is drilled, temperature is measured in depth of a well and then geothermic gradient is defined. On the basis of the results of these measurements, lower boundary depth of PFR ground bed is defined. For this purpose, before temperature in well depth is measured, a casing string (CS) is let down in a well along its sidewall and cemented. After cementing of CS is completed, measurements of temperature inside a well are carried out in the process of cement setting during thermal recovery. The results of temperature measurements are used to plot temperature curve of a well depending on the depth of a well. According to the depressed temperature level of the temperature curve, upper zone of PFR mass bedding inside it and lower zone under it are indicated. Lower zone is the zone of thawed, cooled and/or waterflooded rocks with higher temperature level when the average temperature gradient does not exceed 0.02-0.05°C/m. Between them, an intermediate transition "step" zone is indicated. This is a zone with rapid increase in temperature and high value of temperature gradient (G = 0.06-0.45°C/m and higher). According to the temperature curve and indicated connection point of the "step", which is an intermediate, high-gradient temperature zone with lower thawed, cooled and/or waterflooded zone, the depth of PFR mass bedding is defined. Inside PFR mass, separate local zones of thawed rocks with higher temperature level, frozen zones with depressed temperature level and intermediate high-gradient temperature zones lying between them are indicated simultaneously. According to junction points of intermediate zones and thawed zones, the boundaries between thawed and frozen zones located inside PFR mass are defined. In this case, temperature measurements inside a well are made using a highly sensitive thermometer with intervals of temperature measurement in depth of not more than 0.1-0.2 m.

EFFECT: more accurate definition of bottom depth of permafrost rock mass.

2 cl, 2 dwg