scholarly journals STUDI POTENSI MIGAS DENGAN METODE GAYABERAT DI LEPAS PANTAI UTARA JAKARTA

2016 ◽  
Vol 8 (1) ◽  
pp. 23
Author(s):  
Saultan Panjaitan ◽  
Nyoman Astawa

Anomali Bouguer dapat dibagi kedalam dua kelompok yaitu: Anomali gayaberat rendah terbentuk pada kisaran nilai 15 mGal hingga -40 mGal sebagai rendahan sinklin. Anomali gayaberat tinggi terbentuk pada kisaran nilai 40 mGal hingga 60 mGal sebagai tinggian antiklin. Formasi batuan dari atas hingga bawah sebagai berikut: Formasi Cisubuh rapat massa batuan 2.5 gr/cm³ ketebalan pada penampang ±1400 meter. Formasi Parigi rapat massa batuan 2.7 gr/cm³ ketebalan ± 400 meter. Formasi Cibulakan rapat massa batuan 2.6 gr/cm³ ketebalan ± 1600 meter. Formasi Jatibarang rapat massa 2.8 gr/cm³ ketebalan ± 1000 meter. Batuan reservoir didominasi lensa-lensa batupasir Formasi Cibulakan Atas, Cibulakan Bawah serta batugamping Formasi Parigi dan batupasir Formasi Talangakar. Batuan induk migas adalah serpih lakustrin halus Anggota Cibulakan Bawah (Formasi Talang Akar). Tinggian batuan reservoir pada anomali sisa antara 0 mGal hingga 16 mGal dan kedalaman pada penampang ± 1500 meter dengan rapat massa batuan 2.7 gr/cm³ Sesar normal terbentuk arah Utara-Selatan dan sesar naik arah Timur-Barat dikontrol oleh pematahan bongkah pada batuan alas metamorf dengan rapat massa 3.0 gr/cm³. Kata kunci: gayaberat, antiklin, anomali sisa, lepas pantai. Bouguer anomaly can be grouped into two parts: Low Gravity anomaly formed at 15 mGal to 40 mGal as syncline lower. High gravity anomaly formed at 40 mGal to 60 mGal as anticline high. Rock formation from the top to the bottom as follows: Cisubuh Formation rock of density with 2.5 gr / cm³ thickness at section of ± 1400 metre. Parigi Formation rock density of 2.7 gr / cm³ thicknees ± 400 metre. Cibulakan Formation density with 2.6 gr / cm³ thickness ± 1600 metre. Jatibarang Formation with density 2.8 gr / cm³ of thickness ± 1000 metre. Reservoir rock is dominated by lens of sandstone upper Cibulakan Formation, Lower Cibulakan and also Parigi Formation limestone and Talangakar Formation sandstone. Sourced rock of oil and gas from shales lacustrine of Cibulakan Lower or Talang Akar Formation. High Rocks reservoir at recidual anomaly range from 0 mGal to 16 mGal at section deepness ± 1500 metre with density of 2.7 gr / cm³, formed by normal fault of Northern-Southern direction and reverse fault Eastern-Western direction controlled by block faulting metamorphics bedrock with density of 3.0 gr / cm³. Keywords: gravity, anticline, recidual anomaly, offshore.

2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline. DOI:10.33332/jgsm.2019.v20.1.27-36


2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline.


2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline.


2019 ◽  
Vol 20 (1) ◽  
pp. 27
Author(s):  
Tatang Padmawidjaja

Geophysical research in Tomori Basin, Kolonodale Bay using the gravity method was carried out to identified anticline structural trap in associated with hydrocarbon prospect. The occurence of hydrocarbon seepage in some places, indicate that hydrocarbon have been formed although its distribution is not clearly known. The gravity Bouguer anomaly resulted two groups of rock units: the group of 40 mGal up to 120 mGal gravity anomaly represent ultramafic rocks, and group of 30 mGal up to -80 mGal gravity anomaly reflected a sedimentary rocks basin. The subsurface modeling of the rock density can be grouped into three layers: the Cenozoic (2.5-2.55 gr/cm³ density), the Mesozoic (2.6-2.7 gr/cm³ density), and the Basement ( 2.8-2.9 gr/cm³ density). Elongated and vertical closure are reflected by anomaly 0-2 mGal with density 2.5 gr/cm3 to 2:55 mGal which is supposed to be oil and gas structures. The Source rock is characterized by  0  to -10 mGal anomaly  interpreted as oil kitchen at sub-basin area. Location of the reservoir rock is assumed in the Cenozoic layer on Salodik Group with density of 2.5 gr/cm³. The Basement is estimated at depth of 3.5-4 km, derived from the Group of metamorphic and volcanic rocks.Keyword: Gravity, basin, residual anomaly, fault, anticline. DOI:10.33332/jgsm.2019.v20.1.27-36


2016 ◽  
Vol 13 (2) ◽  
pp. 87 ◽  
Author(s):  
Saultan Panjaitan ◽  
Subagio Subagio

Hasil penelitian gayaberat di Pulau Biak menghasilkan anomali gayaberat yang dikelompokkan kedalam 2 (dua) satuan yaitu anomali gayaberat 50 mGal hingga 120 mGal membentuk rendahan anomali mencerminkan cekungan. Kelompok anomali gayaberat 120 mGal hingga 220 mGal membentuk tinggian anomali. Pola tinggian anomali sisa 0 mGal hingga 2 mGal diduga sebagai perangkap struktur migas yang terdapat di daerah Kota Biak utara, Mandon dan lepas pantai timur P. Pai. Batuan bertahanan jenis rendah antara 0 - 16 Ohm-meter yang mengindikasikan batuan reservoir jenuh fluida terbentuk di kedalaman 2500 meter. Kedalaman batuan dasar terbentuk antara 7000-8500 meter, dengan rapat massa batuan 2.9 - 3.1 gr/cm3 bertahanan jenis tinggi 1000-8200 Ohm-meter diduga sebagai cerminan dari batuan ultramafik kerak samudera. Batuan yang menyusun di daerah penelitian terdiri atas lapisan batuan Tersier dengan rapat massa 2.45 gr/cm3, batuan Pra-Tersier dengan rapat massa 2.75 gr/cm3 dan batuan dasar dengan rapat massa 3.1 gr/cm3. Batuan sumber adalah serpih Formasi Makat berumur Miosen dengan rapat massa batuan 2.45 gr/cm3, sedangkan batuan reservoir terdiri dari batupasir Formasi Mamberamo. Kata kunci Gayaberat, cekungan, migas, anomali sisa, rapat massa, sesar, antiklin, batuan sumber, tahanan jenis. Gravity research on the island of Biak gravity anomalies are grouped into two (2) units is a gravity anomaly 50 mgal up to 120 mgal is basin reflecting. Gravity anomaly 120 mgal up to 220 mgal formed heights anaomaly. Altitude residual anomaly from 0 mGal to 2 mgal is oil and gas as trapping structures contained in the northern City of Biak, off the east coast Mandon and P. Pai. The rocks is of low resistivity between 0 -16 Ohm-meter that indicates the saturated fluid reservoir rocks are in the depths of 2500 meter. The depth of the bedrock formed between 7000-8500 meters, with density 2.9 - 3.1 gr / cm3 is heights resistivity types of 1000-8200 Ohm-meter interpreted as a reflection of ultramafic rocks oceanic crust. The rocks in the study area consists of Tertiary rocks layers with a density 2.45 gr / cm3, the Pre-Tertiary rocks with density 2.75 gr / cm3 and bedrock with density 3.1 gr / cm3. The source rocks is of shale from Makat Formation Miocene age with density 2.45 gr / cm3, and the reservoir rock consists of sandstone Mamberamo Formation. Keywords: Gravity, basin, oil and gas, recidual anomaly, density, fault, anticline, source rocks, resistivity.


Kappa Journal ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 240-249
Author(s):  
Muhammad Zuhdi ◽  
◽  
Jannatin Ardhuha ◽  
Kosim Kosim ◽  
Wahyudi Wahyudi ◽  
...  

The 4D microgravity method is a development of the gravity method with the time as the fourth dimension. This research was conducted to find a better way of interpreting the 4D gravity anomaly due to fluid injection around the reservoir. Researchers used GRABLOX for the interpretation of 4D anomalies around the reservoir. The results of the inversion of field data using GRABLOX provide the value of the injection fluid infiltration volume, which shows the distribution of the injection fluid movement on the reservoir. Another physical parameter that can be generated from GRABLOX with a modified value is the reduction in oil and gas saturation due to fluid injection. The inversion results using GRABLOX in the field data indicate a change in reservoir rock density up to 0.28 gr/cc associated with a reduction in gas and oil saturation. The reduction in gas saturation due to the injection fluid has the smallest value of 0% and the largest is up to 66%. The reduction in oil saturation only contributes to a density change of 20% of the reduction in gas saturation. The results of the GRABLOX trial on synthetic data and field data show that both can provide an identification of the movement of the injection fluid in the reservoir, as well as provide other physical parameters, ie. the reduction in oil saturation due to fluid injection.


2016 ◽  
Vol 9 (1) ◽  
pp. 1
Author(s):  
Anjar Pranggawan Azhari ◽  
Sukir Maryanto ◽  
Arief Rachmansyah

Gravity survey has been acquired by Gravimeter Lacoste & Romberg G-1035 at Blawan-Ijen geothermal area. It was a focusing study from previous research. The residual Bouguer anomaly data was obtain after applying gravity data reduction, reduction to horizontal plane, and upward continuation. Result of Bouguer anomaly interpretation shows occurrence of new faults and their relative movement. Blawan fault (F1), F2, F3, and F6 are normal fault. Blawan fault is main fault controlling hot springs at Blawan-Ijen geothermal area. F4 and F5 are oblique fault and forming a graben at Banyupahit River. F7 is reverse fault. Subsurface model shows that Blawan-Ijen geothermal area was dominated by the Ijen caldera forming ignimbrite (ρ1=2.670 g/cm3), embedded shale and sand (ρ2=2.644 g/cm3) as Blawan lake sediments, magma intrusion (ρ3=2.814 g/cm3 & ρ7=2.821 g/cm3), andesite rock (ρ4=2.448 g/cm3) as geothermal reservoir, pyroclastic air fall deposits (ρ5=2.613 g/cm3) from Mt. Blau, and lava flow (ρ6=2.890 g/cm3).


2016 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Tatang Patmawidjaya ◽  
Subagio Subagio

Paparan Arafura di bagian selatan Kepulauan Aru merupakan depresi Lempeng Indo-Australia yang ditunjukkan oleh anomali gayaberat dan geomagnet tinggi. Sedangkan depresi di bagian utara yang tertahan Palung Aru diperlihatkan oleh anomali gayaberat tinggi dan anomali geomagnet rendah. Anomali ini diduga sebagai penebalan batuan metamorf yang mengalami pangangkatan sebagai alas cekungan Wokam. Analisis data gayaberat dan geomagnet mengindikasikan penurunan cekungan ini ke arah utara. Penurunan anomali gayaberat ke arah Pulau Wokam yang berarah baratdaya-timurlaut di selatan dan baratlaut-tenggara di daerah utara ditafsirkan sebagai struktur sesar. Hal ini dicirikan oleh arah sungai atau selat sebagai pemisah pulau-pulau di Kepulauan Aru. Anomali gayaberat residual mengindikasikan cekungan dan punggungan berarah baratdaya-timurlaut yang membentuk antiklin dan sinklin. Sesar dan lipatan ini menerus sebagai struktur geologi dangkal bawah permukaan. Berdasarkan pemodelan gayaberat dan geomagnet dapat dikatakan bahwa Cekungan Wokam cenderung menurun ke arah utara akibat sesar normal. Kata Kunci : gayaberat, geomagnet, pemodelan geologi, Cekungan Wokam Arafura Shelf in the southern part of the Aru Islands is a depression of the Indo-Australian crust at the south that indicated by high gravity and geomagnetic anomalies. While the northern depression blocked by the Aru Trough indicated by high gravity anomaly and low geomagnetic anomaly. These anomalies presumed as a thickening of the metamorphic rocks due to uplifting and acting as the basement of Wokam Basin. Gravity and geomagnetic analyses indicate a northward subsidence of the basin. The decreasing of the southwest–northeast gravity anomaly in the south and the northwest-southeast in the north, interpreted as a fault. It this characterized by the river direction or strait as islands separation in Aru Archipilagoes. Residual gravity anomaly indicates a southwest-northeast basin and ridge form anticline and syncline. These faults and folds are continuous as the shallow subsurface geological structures. On the base gravity and geomagnetic models, it can be concluded that Wokam Basin tends to subside northward as the result of a normal fault. Keywords: gravity, geomagnetic, geological models, Wokam Basin


2019 ◽  
Vol 8 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Dian Darisma ◽  
Marwan Marwan ◽  
Nazli Ismail

Estimation of the subsurface geological structures in oil and gas prospect area of West Aceh has been done by utilizing gravity field anomaly of satellite gravity data. This research aim to analyze satellite gravity data in order to get geological features which is include deep and shallow structure or fault around oil and gas prospect area in West Aceh. The satellite gravity data is originally provided as Free Air Anomaly and should be corrected to get Complete Bouguer Anomaly (CBA). Furthermore, CBA was transformed into a horizontal plane and corrected from regional anomalous effects to obtain residual anomaly, horizontal and vertical derivative. From CBA, the gravity anomaly show good correlation with geological boundaries on different rock formation and the anomaly is decrease from NE-SW. Residual anomaly also gives same information with CBA but this anomaly focus on shallow structure. Furthermore, horizontal derivative and vertical derivative also show good correlation with geological structure or fault but in some areas the anomaly related with deep structure cannot be seen on the surface or geological map. Despite the result cannot correlate directly with oil and gas prospect area, satellite gravity can be used to identify gravity anomaly and also fault that related with hydrocarbon anomaly area


2018 ◽  
Vol 36 (5) ◽  
pp. 1136-1156 ◽  
Author(s):  
Yuanhua Qing ◽  
Zhengxiang Lü ◽  
Xiandong Wang ◽  
Xiuzhang Song ◽  
Shunli Zhang ◽  
...  

The oil and gas in the Palaeogene lacustrine carbonate rock reservoirs in the Bohai Sea accumulated during several periods. The reservoir porosity formed during each period affected the degree of accumulation that occurred. In this paper, the percentages of particles, authigenic minerals and pores in the reservoir bed were calculated with the statistical method of microstructure analysis. The formation time was determined with an isotopic analysis of the authigenic carbonate minerals and the homogenization temperature of the gas–liquid inclusions. The percentages of the primary intergranular pores that formed during the different stages were recovered based on the compaction features both before and after the formation of the major authigenic minerals. The evolution of porosity was thus described quantitatively and chronologically, employing the percentages of the residual primary intergranular pores, visceral cavity pores and dissolved pores at the different burial depths. The results indicate that in the initial sediments of the reservoir rock, the primary intergranular porosity was 32.4%. During the early burial stage, the total reservoir porosity increased by up to 46.9%, due to the addition of another type of primary pore, namely visceral cavity pores, which were generated from the decomposition of bioclasts. During the late, deep burial stage, the compaction reduced only 8.2% of the porosity, due to the support of the pore-lining dolomite precipitating during the early stage. Authigenic minerals occupied 12.6% of the porosity, and the dissolution created the secondary porosity by 3.8%. Good preservation of the visceral cavity pores and the growth of the pore-lining dolomites during the early stages are the major factors leading to the high reservoir porosity. The quantitative and chronological characteristics of the reservoir porosity evolution could be described accurately. The prediction of reservoir beds can be better guided than in previously reported methods by applying high resolution microscopic quantitative analysis technology and authigenic mineral timing analysis technology.


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