In the given work the estimation of efficiency of practice of wide application of horizontal drilling on Sugmut reservoir, one of the largest in Russia is presented.
The reservoir is in development of 10 years, significant reserves of oil are concentrated in a water-oil zone. At the first stage of drilling, at realization of three-row system of development by vertical wells there was a problem of non-uniform development of reserves with formation of the centers of active movement of fluids and stagnant zones, effects early water cut wells, annulus overflows were showed.
During search of new decisions by means of hydrodynamical modelling the estimation of set of variants of the further drilling on oil formation has been lead, is chosen optimum, providing reduction of densitygrids and mass application of system of horizontal wells with horizontal length of wellbore up to 1300 m. Realization of the chosen strategy immediately has led to essential growth of levels of extraction, decrease in rates of water cut wells.
Within last four years work of separate horizontal wells proceeds in the waterless period with well producing rateup to 1500 ?onn/d. On practical experience it is proved, that system engineering of horizontal wells allows to increase essentially rate of development of reserves, considerably to prolong the waterless period of operation. Thus the density of a grid of wells decreases, the front of replacement is leveled; the problem of water cone decreases; the favorable front of distribution of pressure is created; there is an opportunity to provide development of reserves along line water-oil contact.
Feature of development of a reservoir is that on uniform on geological structure and permeability properties the areas essentially various systems of development are realized, in operation there are wells with various orientation of a horizontal part of well concerning natural permeability properties. An actual trade material available on today has provided the richest information for comparison purposes applied technologies, revealings of problems, extraction of lessons for the further optimization of development that is presented in work.
General feature of reservoir
Sugmut reservoir is one of the largest reservoirs opened recently. Its industrial development is connected with development of layer BS9–2, begun in 1995.
The reservoirinclude the layer BS9–2 not structural type, extended by a strip from the north on the south, length about 70 km, width 5–14 km. It is characterized sharp litology by heterogeneity. The zone of the maximal thickness is traced on an axial line from the north on the south. Porosity on a core in an oil zone of 15,3 % (on logging - 17 %), in a water-oil zone porosity on a core and logging are practically equal - 17,78 % and 18 %, accordingly. Permeability of collectors according to hydrodynamical researches on extracting wells varies from 2 up to 25 md and on the average on a layer 15,7 md. By the petrosated part of a layer on materials logging average permeability is equal 79,8 md.
The created geological model of reservoir reflects complex a structure of layer BS9–2. In a cut are allocated 7 packslayes developing and gradually replacing one another in a direction from the east on the west.
Large oil reserves are concentrated in water-oil zones of reservoir.