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Geological Engineering
113
Comparison of actually achieved and predicted gas recovery factors for the Urga field
Table 3.
Batch
Porosity, %
from-to
average
Gas saturation
from-to cf.
Gas
recovery
coefficient
according
to MPD
current
Group
according
to
К
иг
Forecast
coefficient.К
иг
J
3
1
22,8
0,82
-
В
0,75
J
3
2
22,7
0,85
0,76
*
/0,5
А
0,85
J
3
2а
16,5-20,5
18,2
0,7-0,8
0,77
-
В
0,75
J
3
3а
+J
3
3б
17,7-18,7
18,2
0,74-0,75
0,74
0,54
*
/0,85
В
0,75
J
3
5
18,7
0,75
-
В
0,75
J
3
6
15,7
0,74
0,62
*
/0,52
С
0,65
J
3
7
18,4
0,78
0,06
*
/0,08
В
0,75
J
3
8
14,3
0,77
-
Д
0,55
Average value
0,725
Predicted gas recovery factors for the field Surgil-North.Aral
Table 4.
Productive
batch
К
p
, %
from-to
average
К
pr
from-to
average
Group acc. to
table 1.1
extraction coeff.
J
3
1
22,4-26
25
0,59-0,66
0,64
А
0,85
х
J
3
2
20,8-22
21,5
0,62-0,65
0,63
В
0,75
х
J
3
3
23-28,5
25
0,57-0,7
0,63
А
0,85
х
J
3
3а
23
0,65
В
0,75
х
J
3
4
16,8
0,55-0,59
0,57
С
0,65
х
J
3
5
22,5-22,9
22,7
0,63-0,64
0,63
В
0,75
х
J
3
5а
24,0-24,2
24,1
0,64-0,67
0,65
А
0,85
х
J
3
6
18-23,8
20,7
0,6-0,72
0,66
В
0,75
*
J
3
7
17-22,6
19,8
0,6-0,72
0,66
В
0,75
+
J
3
7а
19
0,62
В
0,75
»
Average value J
3
:
0,77
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114
J
2
1а
20-24
22
0,58-0,7
0,65
В
0,75
+
J
2
2
18,1-21
20
0,66-0,75
0,7
В
0,75
*
J
2
3
18,8-22
20,5
0,69-0,72
0,7
В
0,75
+
J
2
4
16,0-19,3
17,5
0,6-0,7
0,65
С
0,65
+
J
2
5
18-18,8
18,5
0,7-0,73
0,71
С
0,65
*
J
2
6
12-20,8
16,5
0,62-0,75
0,67
С
0,65
*
J
2
7
14-19,3
17,5
0,63-0,72
0,67
С
0,65
*
J
2
8
15-23
19
0,57-0,74
0,6
С
0,65
*
J
2
9
14,6
0,62
Д
0,55
х
J
2
10
14,6-16,2
15,4
0,61-0,75
0,66
Д
0,55
*
J
2
11
11-20
15,5
0,62-0,78
0,7
С
0,65
+
Average value J
2:
0,69
Average value:
0,73
Predicted gas recovery factors on the East. Berdakh
–
Uchsay
Table 5.
Productive
batch
К
p
, %
from-to
average
К
pr
from-to
average
Group acc. to
table. 1.1
Forecast of gas
extraction coeff.
J
3
7
19,2
0,7
В
0,75
J
3
8
17,6
0,65
С
0,65
J
3
9
17,7
0,65
С
0,65
J
3
10
18,8
0,65
В
0,75
J
3
11
15
0,6
Д
0,55
Average value J
3
:
0,67
J
2
1
15
0,65
С
0,65
J
2
2а+2б
15
0,65
С
0,65
J
2
3
15
0,65
С
0,65
J
2
4
13,2-15
14,2
0,66
Д
0,55
J
2
5
14-15
14,5
0,73
Д
0,55
J
2
6
13-14
13,5
0,7
Д
0,55
Geological Engineering
115
J
2
7
19,2
0,7
В
0,75
Average value J
2
:
0,62
Average value:
0,65
Group B includes 3 reservoirs (J
3
7
, J
3
10
, J
2
7
), in which 37 % of the total reserves are
concentrated.
Group C includes 5 reservoirs (J
3
8
, J
3
9
, J
2
1
, J
2
2а+2б
, J
2
3
) with 37.0 % reserves.
Group D includes 4 reservoirs (J
3
11
, J
2
4
, J
2
5
, J
2
6
) with 26 % reserves.
2. The average gas recovery for the field is 0.65, which is slightly lower than for the Urga
and North Aral-Surgil fields.
Based on the final gas recovery estimate, a histogram of the distribution of this parameter
(Fig. 3) was constructed separately for J
2
and J
3
(Fig. 3 a) and in the sum J
2
+ J
3
(Fig. 3 b). These
histograms reflected the corresponding samples and were processed statistically [11]. As a result
of statistical processing, it was found that the average values of all samples are practically equal
and amount to К
ex.g
=0,7. The variances of these values, respectively, are σ
2
К
ex.g
J
3
=0,005; σ
2
К
ex.g
J
2
=0,006; σ
2
К
ex.g
J
2+3
=0,011 and the standard deviations: σКex.g(J
3
)=0,07; σК
ex.g
(J
2
)
=0,08;
σК
ex.g
(J
2+3
)=0,1.
a)
b)
Figure 2 - Histograms of gas recovery factor distribution (I
2
, I
3
)
a) histogamma of the distribution of the final gas recovery separately for J
2
and J
3
b) histogram of the distribution of the final gas recovery in the sum J
2
+ J
3
Therefore, the К
ex.g
value for each section of the section will be according to the formula:
x
x
x
(2)
- J
3
0,63 < К
ex.g
< 0,77;
- J
2
0,62 < К
ex.g
< 0,78;
- J
2+3
0,6 < К
ex.g
< 0,8.
Findings.
For the fields of Uzbekistan, gas deposits which are confined to terrigenous
reservoirs and which are either completed or are at a late stage, the gas recovery factor varies
from 0.5 to 1, with an average value of 0.64.
Such a scatter of К
ex.g
values allows us to conclude that for some deposits there is both
underestimation and overestimation of gas reserves.
In addition, the absence of a correlation between К
p
ef
=К
p
general
К
g
and the gas recovery
factor К
ex.g
suggests that the value of К
g
for most of the fields is underestimated, since the
Geological Engineering
116
calculation of reserves for these deposits was carried out in the 50-60 s of the last century, when
this parameter was determined mainly by the method of centrifugation on the core. As studies of
recent years have shown, this method, with a not optimally selected mode, gives overestimated
values of К
r.w
, and, consequently, underestimated К
g
. Therefore, there is a possibility of an
increase in reserves for these fields due to the revision of К
г
.
The average К
ex.g
values generally coincide with the estimates for other fields in various
oil and gas regions of the world, which gives rise to their use in assessing the gas recovery factor
at the fields where prospecting and exploration are being carried out, in particular, at the fields of
the Sudochniy. To estimate the gas recovery factor for the Sudochiy fields, it is recommended to
take the following factors: J
3
– 0,7; J
2
- 0,69; J
1
- 0,55.
References
[1]
Abidov A.A., Khalismatov I.Kh., Burlutskaya I.P. Podschet izvlekayemix zapasov
prirodnogo gaza na mestorojdeniyax uglevodorodov - osnova dlya vnedreniya
resursosberegayushix texnologiy razrabotki// Uzbekskiy jurnal «Problemi energo - i
resursosberejeniya». 2005g., str. 31-36.
[2]
Begmetov
E.Yu.,
Khalismatov
I.Kh.,
Gom
S.Yu.
O
sovershenstvovanii
geologorazvedochnix rabot v Ustyurtskom region v svyazi so slojnostyu geologicheskogo
stroyeniya mestorojdeniy (na primere mestorojdeniya Vostochniy Berdax-Uchsay ).
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[3]
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[4]
Vezirova R.Kh. Vozmojnosti otsenki konechnoy gazootdachi produktivnix plastov gazovix
mestorojdeniy Midkontinenta (SSHA). II sb. Geologiya, bureniye, razrabotka i
ekspluatatsiya gazovix i gazokondensatnix mestorojdeniy, M., Gazprom, vip. 3, 1991.
[5]
Ivanova M.M. et al. // Geologiya neftegazovix mestorojdeniy M., Nedra, 2001.
[6]
Karimov A.K., Khalismatov I.Kh., Smanov A. et al. Anliz geologo-geofizicheskix
materialov i obobsheniye rezultatov razrabotki mestorojdeniy Ustyurtskogo
neftegazonosnost regionov s selyu utochneniya konechnoy gazootdachi. Uzbekskiy jurnal
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[7]
Lerner U., Mitchell D. et al. On the issue of gas recovery of gas-bearing terrigenous
reservoirs of the Perm province of Pennsylvania. // Oil and Gas Maqasin No. 3 P.81-95,
2002 (translated from English).
[8]
Metodicheskiye rekomendatsii po opredeleniyu podschetnix parametrov po dannim
geofizicheskix issledovaniy skvajin. Vendelshteyna B.Y., Pod redaksiyey Kalinin, 1990g.
[9]
Omes S.P., Romanovskaya N.S. O prirode gazovix plastov Medvejyego mestorojdeniya. //
Geologiya i razvedka gazovix i gazokondensatnix mestorojdeniy, vip.6, VNIIE Gazprom,
Moskva: 1976.
[10]
Problemi dobichi gaza iz terrigennix kollektorov. // Edited by S.N. Nazarenko M.,
Gazprom, 1995.
[11]
Porotov S.N. Matematicheskiye metodi modelirovaniya v geologii. Izd. Sankt-
Peterburgskogo gosudarstvennogo gornogo universiteta, SPB, 2005g.
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