Georesursy (Sep 2017)
The Role of Horizontal Wells when Developing Low-Permeable, Heterogeneous Reservoirs
Abstract
The widespread use of horizontal drilling in recent years has shown that horizontal wells can be successfully used both at the initial and late stages of development. This is due to the fact that horizontal wells, in contrast to vertical wells, contact a larger area of the productive formation, while the surface of drainage of the oil-saturated layer, productivity of the wells due to the formation of cracks, and also the influence on thin layers increases. One of the methods of impact on the reservoir is the steam-thermal method. The main advantage of the use of the heat wave method in horizontal wells is a significant increase in the well production rate, a decrease in the water cut of the reservoir, a decrease in the oil viscosity, an increase in the injectivity of the injection well, and an increase in the inflow in producing wells. As a result of the total effect, a significant increase in production is obtained throughout the entire deposit. Enhanced oil recovery from the injection of steam is achieved by reducing the viscosity of oil, covering the reservoir with steam, distilling oil and extracting with a solvent. All this increases the displacement coefficient. One of the most effective ways to increase oil recovery at a late stage of field operation is sidetracking in emergency, highly watered and low-productive wells. This leads to the development of residual reserves in weakly drained zones of reservoirs with a substantial increase in well productivity in low-permeable reservoirs. This approach assumes that the initial drilling of wells is a ‘pilot’ stage, which precedes the development of oil reserves in the late stages of deposit development. In the fields of Western Siberia, multiple hydraulic fracturing of the reservoir has been improved due to a special stinger in the liner hanger of multi-packer installation, which excludes the influence of high pressures on the production column under the multiple hydraulic fracturing. Employees of BelNIPIneft RUPPO Belorusneft have developed equipment and technologies for creating a network of deep permeable radial filtration channels under the SKIF trademark, which is based not just on multiple hydraulic fracturing of a formation, but on hydraulic fracturing in each of the interlayers creating a network of deeply penetrating radial channels. The calculations show that the technology of deeply penetrating radial channels significantly increases the production rates in comparison with the multiple hydraulic fracturing technology. In China and other countries, deep-seated, low-permeability carbonate reservoirs are operated with the use of an acid fracturing in open horizontal trunks with two technological innovations at the final stage of drilling: reorientation of the fracture and retraction of the fluid.
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