M.S. student Yeszhanov
D.O.
Kazakh National
Technical University after K.I.Satpaev
Almaty, Kazakhstan
Innovative method of oil
recovery enhancement
There are known hundreds oil fields
in the CIS’s territory which are bedding at a depths of more than 600m, and at
the mines using underground method - over 1000m. Recovery factor at these fields
does not exceed 0.3-0.4. After oil recovery from
these fields according to current technology there even more half of reserves remain
in the bowels. Such fields are located mainly in the developed old regions of
Kazakhstan (in Atyrau and Mangystau regions).
For research of oil
production enhancement methods from reservoirs in Kazakhstan there is offered
use of recovery methods with application of gravity depletion through
underground mine workings and drainage wells (downhole method).
It is possible to
present following data regarding efficiency of mine-borehole methods of oil
recovery. Developed projects for construction of experimental oil mines in Makat
(Kazakhstan) and Balakhan (Azerbaijan) have shown that the cost price of 1t oil
will be approximately 6 usd. Drainage of oil reservoirs by inclined and upward
borehole passed from mine workings creates favorable conditions for thermal
influence on oil reservoirs. Due to that fact, mathematical models of
thermodynamic condition of reservoirs during impact on them of long-acting heat
sources are developed. It will accelerate the problem solving of total extraction
of residue oil reserves from bowels.
Scientific foundations of innovative mine-borehole concepts of oil fields
development, pursuing the main objective –increase of well production rate of
oil fields in comparison with traditional operating procedure at the expense of
use of gravitation forces and, consequently, final oil recovery enhancement. It
should be noted that this method is especially preferable to development of
fields with extra-heavy crude oils bedding at rather shallow depths as, in most
cases, special difficulty at extraction by known widespread methods is
extraction of such oil type.
Innovative mine-borehole
method of oil fields development, as a whole, is applicable for depths average to
2000m.
Specifically, this method is
interesting during development of offshore (shelf) oil fields in Kazakhstan as,
in this case, the drilling and opening-up of production horizon is executed not
through water, and through the mine workings which have been passed ashore and
under sea floor. Due to this factor, requirements and norms for environment
protection during drilling, opening-up of production interval and during
subsequent hydrocarbon production on the sea sharply reduce, in a view of the
fact that requirements and norms for environment protection during offshore
fields development several times above in comparison with development of the
same fields overland. But it shouldn’t be confused with horizontal well-drilling.
It is known in the whole world, that at the present time, in general, the mean
oil recovery factor is equal to 0.3-0.4, rarely reaches to 0.5. Thus, more (more
than 50%) of geological reserves of hydrocarbons remain in the formation. Our
method assumes correction of oil recovery factor by 1.5-2 times in comparison
with current position and at offshore fields.
Meaning of new mine-borehole technology consists in the following [1]:
1) First of all, we
construct vertical well from surface, as close to oil-drainage boundary as
possible (to drainage area), (mine diameter to 4-8m), to depth below the interval
of interest to us productive oil deposit on the shelf;
2) There is laid “cross-strata
heading” from shaft along stratum aside bedding of productive deposit. Thus, go
under oil deposit and start bottom-up drilling-out of interest to us production
horizon according to technology of upward (uprise) drilling with technology of
well casing, cementing in water, as during bottom-up formation exposing there
is assumed, first of all, possible exposing of water-bearing horizons (bottom waters).
Well is cased, cemented and perforated opposite to interval of interest;
3) For lifting of well production
on the surface to production well along horizontal bend of cross-strata heading
there is laid exhaust lines falling to shaft, and along vertical bend,
accordingly, stalks ;
4) For construction of mine, wells,
drilling-out of deposit, laying of exhaust lines, stalks it is required
attraction of people for works both on surface and in underground openings. In
this connection, for creation of optimum operating conditions (first of all,
temperature control at a depth) there is planned erection of ventilation;
5) During oil recovery, for
production lifting on the surface through exhaust lines there will be installed
booster pumps of different capacities depending on deposit burial depth, consequently,
from formation pressure and subsequent drawdown in reservoir.
Main advantages of this field development method consist in the
following [2]:
1) Reduction of norms
and requirements for environment protection during development of offshore (shelf)
fields due to the absence of drilling and other operations in the sea, thus, it
excludes any possibility of pollution
of the sea areas, waters and damage of sea flora and fauna;
2) Oil movement at this method does not subject to gravity, rising
upwards from depths, creating uplift pressure on reservoir, as at normal,
standard operating procedure. On the contrary, under positive gravity plus at
the expense of depletion energy there is created maximum drawdown in reservoir close
to or nearly not differing from formation pressure that is barely impossible to
reach at traditional methods of development.
Thus, oil falls down through producing well with
increased production, exceeding existing production owing to what there is total
extraction of hydrocarbons, and consequently, oil recovery factor increases significantly. These main advantages
allow considerably increasing of oil recovery, to extend the life of the oil
producing companies and to reduce oil extraction factor practically up to 0.6-0.8.
List of sources:
1. Patent RK ¹2008/0001.1 dated 03.01.2008. Method of extra-heavy oil
development. Oryngozhin E.S., and other.
2. Moldabaeva G. Zh.
Mine-borehole method of oil recovery. Scientific and technical maintenance of mining
practice. Transactions, volume 79, 2010.