The Use of Block Permeability Fractured Reservoir Model for Engineering Horizontal Well Bores (Russian)

Kiselev, Valeriy (Siberian Federal University) | Kinsfator, A. R. (RN-KrasnoyarskNIPIneft Ltd.) | Antonenko, A. A. (RN-KrasnoyarskNIPIneft Ltd.) | Chaskov, A. V. (OJSC VCNG)

OnePetro 

The pdf file of this paper is in Russian.

Abstract

The permeability of fissured reservoirs is characterized by a pronounced spatial anisotropy, which must be taken into account during the field exploitation [1-10]. Data on the anisotropy permeability can greatly assist in the interpretation of the results of well interference testing and hydrodynamic studies.

Earlier, we introduced a new (bloc) permeability fissured reservoirs model [11-12]. The equation for the directional permeability as a function of spherical coordinates and the two constants, determined according to the distribution of the incidence angles and trending azimuths of fissures and linear dimensions of impermeable blocks was established. The principal difference between our model and the earlier one is that, firstly, statistical distribution of orientation and the linear dimensions of the blocks were taken into account. Secondly, we examined a system of hydrodynamically interconnected fissures.

According to geophysical studies of well bores, 3D seismic measurements and core analysis, a database of spatial orientation and size of the blocks much of the productive Riphean deposit of Yurubcheno-Tokhomskoye oil field were established. This data is used to identify the directional anisotropy of permeability. In addition to the previous studies, blocks, which cross-sections at the bottom was not square, but rectangular, was examined. The ratio of the rectangle bores were determined by the number of orthogonal fissures within the reservoir studied interval.

An algorithm for the calculation of the average directional permeability, which characterizes the flow of fluid to the horizontal bore, was established. Calculations have shown that this quantity depends strongly on the azimuth of the horizontal bore. If there will be a deviation from the optimum azimuth of the bore lines, even in the (5-10)0, flow of fluid to the bore may be reduced by more then ten percent. Another practically important result that follows from the calculations, is that the optimal direction of the horizontal bore must be oriented not perpendicular to the preferred fissure (as it is currently in the engineering of horizontal well bores), but at the angle other than 900. The value of this angle depends on the anisotropy of permeability and can be calculated.