PROCEDURE FOR CONSTRUCTION OF HORIZONTAL WELL IN DEVONIAN STRATA Russian patent published in 2011 - IPC E21B7/06 

FIELD: oil and gas production.

SUBSTANCE: procedure for construction of horizontal well in Devonian strata consists in driving vertical section, section of initial curve with inclination angle built-up according to project, sections of inclination angle built-up coming to horizontal and in drilling horizontal borehole. To reduce probability of drilling tool freeze-in clay of Kynovsk horizon is driven at inclination angle α_entr less, than 60°. Also, if inclination angle αentr is 50-60°, then a casing string is lowered into a borehole with entry into upper limestone and cemented. If inclination angle α_entr is 45-40° and less, than a borehole is cased with a casing string and cemented after there is reached a bottomhole of a well of the pay horizon by drilling according to a project profile. Actual value of inclination angle of entry into upper limestone on floor of Kynovsk horizon α_entr is determined with distance from upper limestone to a project oil reservoir A and radius of curve R at reaching curve in this interval to a required value according to formula: α_entr=arc sin (1-A/R), where α_entr is inclination angle of entry into upper limestone on floor of Kynovsk horizon, in degrees. A is a distance from upper limestone to a project oil reservoir, m, R is radius of drift angle build-up in the interval from upper limestone to a project oil reservoir, m, when value of A is reached at allowed value of intensity of curve for a given drill tool and casing string assembly.

EFFECT: reduced probability of drill tool freeze-in, reduced period of construction of well, reduced material expenditures.

2 cl, 1 dwg, 1 ex