RU95109767A - Method for development of multiple-bed deposit by system of horizontal wells - Google Patents

Abstract

FIELD: oil production industry. SUBSTANCE: multiple-bed oil deposit is developed by system of horizontal wells with preliminary determination of length of horizontal hole of well in each interlayer with taking into consideration its hydraulic permeability. According to method, additionally performed are field and laboratory investigations with determination in each interlayer of output of vertical wells, non-uniformity as to permeability and initial oil saturation, and also balance and movable reserve of oil, coefficient of displacement. Horizontal bore-hole of well is driven through reservoir with distribution of its length through interlayers according to formula:, where L- total effective length of horizontal well;, where n - number of interlayers (beds) of multiple-bed oil deposit; i, j - index of actual interlayer; r - average number of well operating days per year, 24 h;- output of vertical well per unit of conductanceof i-bed, t/day;- coefficient of permeability of i-bed, mcm 2;- effective oil saturation capacity of i-bed, m;- movable oil reserve of i-bed per single well and per 1 m of effective oil saturation thickness of bed h;- maximal calculated water content of well product in i-bed determined with respect to physico-chemical properties of oil and displacing agent, hydrodynamic characteristics and coefficient of oil displacement by injected agent;- average calculated water content of well product at end of development; at moment of reaching Ain every interlayer;- coefficient of flooding; A- accumulated intake of liquid in conditions of beds in proportions of movable oil reserve, determined with respect to non-uniformity of bed as to its permeability and A. Method ensures simultaneous extraction from all beds and cuts entire deposit development periods. All extracted oil reserves are taken at reduced accumulated liquid. EFFECT: high efficiency.

Claims (1)

The invention relates to the oil industry, and in particular to methods for developing multilayer oil fields using a horizontal well system. The inventive method for developing a multilayer oil field by a system of horizontal wells with preliminary determination of the length of the horizontal wellbore in each layer, taking into account its hydroconductivity, additionally conduct field and laboratory studies with the determination of the rate of vertical wells for each layer, heterogeneity in permeability and initial oil saturation, as well as balance and moving oil reserves and displacement factors, and horizontal wiring of the wellbore is performed through the manifold to the distribution of its length by the formula interlayers

where L _{total GS} - the total effective length of the horizontal well;

where n is the number of layers (layers) of a multilayer oil field; i, j is the index of a particular interlayer; τ - is the average number of days of well operation in a year, days;

flow rate per unit conductivity

first layer, t / day;

permeability coefficient of the i-th layer, microns ² ;

effective oil-saturated power of the i-th layer, m;

mobile oil reserves of the i-th formation per 1 well and 1 m of its effective oil-saturated thickness

A _i - estimated marginal water cut of well production in the i-th formation, determined taking into account the physicochemical properties of the oil and the displacing agent, the hydrodynamic characteristics and the coefficient of oil displacement by the injected agent;

the estimated average water cut of well production at the end of development, at the time of reaching A _i for each layer;

water flooding ratio; F _i - accumulated fluid withdrawal in reservoir conditions in fractions of mobile oil reserves, determined depending on the heterogeneity of the formation by permeability and A _i . The method ensures the simultaneous development of all formations and reduces the development time of the field as a whole. All recoverable oil reserves are selected with less accumulated fluid withdrawal. Higher oil recovery rates are achieved with approximately the same maximum annual rates of oil recovery from initial recoverable reserves.