PEMODELAN GEOSTATISTIK UNTUK MENGETAHUI SEBARAN KANDUNGAN GAS METHANE DAN POROSITAS PADA SEAM BATUBARA FORMASI WARUKIN DIDAERAH TAMIANG LAYANG KAB. BARITO TIMUR
This study was conducted to determine coal seam which has high permeability as coalbed methane reservoir. Determination of high permeability zones was approached by using grid model of high anomaly value of porosity log and high anomaly value of gas content, both lateral and vertical distribution...
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| Format: | Theses and Dissertations NonPeerReviewed |
| Published: |
[Yogyakarta] : Universitas Gadjah Mada
2015
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| Online Access: | https://repository.ugm.ac.id/134797/ http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=77944 |
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| Institution: | Universitas Gadjah Mada |
| Summary: | This study was conducted to determine coal seam which has high permeability as
coalbed methane reservoir. Determination of high permeability zones was
approached by using grid model of high anomaly value of porosity log and high
anomaly value of gas content, both lateral and vertical distribution. Good coal
permeability zones have a high reflection of log porosity values and gas content
values.
Porosity log values used in this study was calculated using the method of Serra
(Serra. 1984) based on short density log ( SD ) and long density log ( LD ) data
input, while the gas content values using the equation of Kim (Kim , 1977). To
determine porosity log value and gas content value on particular wells which have
no data, a regression linear equation has been employed. After porosity log value
and gas content value on the whole point of all well already recovered, then
further step for estimating value of porosity log and gas content, both lateral and
vertical distribution on all grid areas can be modeled by using linear regression for
cokriging method.
Coal seam zone on North East (NE) deposit has a very high kernel density
anomaly index, however it has a very low anomaly value of porosity logs and
gas content. It is interpreted that those may be effected by intensively tectonic
activity on this side areas. As a result, causing changes in direction of cleats
orientation. In addition, uplifting has changes coal seam deposit closed to the
surface and make weathering index become much higher, consequently coal might to be powdered. The coal powder may fill openings pulverization of cleats
and impede flow of gases and fluids.
Coal seam deposit in research area that has a high distribution value of log
porosity is located on the Southwest (SW). This is caused by cleat permeability in
this zone is formed with excellent under traction (burial) conditions which
occurred by the result of uplifting on North East (NE) of research area. Result of
lineament extraction shown in this potential zone is not much influenced by
excessive tectonic intensity, so that the lineament is not much developed. Trend of
overall anomalies of gas content on each coal seam shows a high anomaly with
increasing depth of overburden which influence the accumulation of hydrostatic
pressure. By increasing hydrostatic pressure, gas content value in coal seam will
be higher. Total gas in place resources inside sweet polygon area (650,8 Ha)
having a high anomaly value of porosity log and gas content is 540.55 MM SCF
approximately.
Anomaly of gas content values inside sweet polygon area were obtained by using
Kim equation (Kim, 1977), has showed different trends with anomaly of porosity
log values. The difference between trend of porosity logs values and gas content
values (Kim, 1977), can be answered through gas desorption isotherm formula
which has proposed by the authors in this study. The difference of those trend is
due to the interconnection with the cleat fracture system outer equilibrium
pressure (disequilibrium pressure). Consequently, accumulation of gas at high
porosity coal seam zones migrate toward lower hydrostatic pressure zones |
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