Zaputlyaeva EGU 2018: Cairan mantel di lapangan migas sekitar Lusi

EGU2018-579

Cairan yang berasal dari mantel di lapangan minyak dan gas bumi di sekitar semburan  Lusi, Timurlaut Jawa, Indonesia

Mantle-derived fluids in the oil and gas fields around the Lusi mud eruption, NE Java, Indonesia

From <https://meetingorganizer.copernicus.org/EGU2018/posters/27155

Geophysical Research Abstracts Vol. 20, EGU2018-579, 2018 EGU General Assembly 2018 © Author(s) 2017

Alexandra Zaputlyaeva (1), Adriano Mazzini (1), Antonio Caracausi (2), Henrik Svensen (1), and Alessandra Sciarra (3)

(1) CEED, University of Oslo, Norway (alexandra.zaputlyaeva@geo.uio.no),

(2) Istituto Nazionale di Geofisica e Vulcanologia (INGV) Palermo, Italy ,

(3) Istituto Nazionale di Geofisica e Vulcanologia (INGV) Rome, Italy

Ditinjau Oleh: Dr. Hardi Prasetyo

Sciences Manager,  Misi Nasional Penanggulangan Bencana LUSI

2006-2017, Kerjasama BPLS-LUSI LAB

TINJAUAN: EGU 2018

Abstrak

Lusi adalah semburan lumpur yang sedang berlangsung di Timurlaut Jawa, Indonesia, yang dimulai pada bulan Mei 2006.

Induk sediman Sistem hidrotermal yang aktif ini (This active sediment-hosted hydrothermal system) terletak pada suatu cekungan sedimen di busur belakang yang kaya material hidrokarbon (in a hydrocarbon-rich back-arc sedimentary basin), yang hanya berjarak sekitar 10 km dari gunung api berumur Holosen terdekat.

Tiga lapangan minyak dan gas bumi terletak di sekitar Lusi (3-5 km ke barat, barat daya dan timur laut).

Akumulasi hidrokarbon (HC) terbatas pada reservoir Pleistosen klastik volkanik dangkal pada kedalaman 400-700 meter, dan produksi saat ini terutama gas alam, sedangkan minyak diproduksi pada tahap awal.

Percontohan dari bidang HC ini dilakukan pada tahun 2017 dalam kerangka proyek Lab ERC Lusi.

Gas telah dianalisis dengan kromatografi gas dan spektrometri massa spektrum isotop.

Hasilnya menunjukkan bahwa gas tersebut didominasi metana, dengan homogen metana yang lebih tinggi hadir juga, di mana nilai isotop karbon dan hidrogen dari metana menunjukkan asal jenis termogenik.

Rasio helium isotop yang meningkat (3He/4He) serupa dengan nilai dari fumarol di gunung berapi Welirang (fumaroles of the Welirang volcano), yang berjarak 25 km ke barat daya dari daerah studi, menunjukkan sumber mantel helium (suggesting a mantle source of the helium),

Selain itu, nilai 3He/4He (Elevated helium isotope ratios) yang serupa diukur pada kawah, gas didominasi CO2 dari Lusi (CO2-dominated gas venting from Lusi) dan dari rembesan satelit didominasi oleh CH4 (from CH4-dominated satellite seeps), menunjukkan kurangnya korelasi antara spesiasi gas dan rasio isotop helium (demonstrating a lack of correlation between gas speciation and helium isotope ratios).

Data menunjukkan bahwa baik reservoir HC dan sistem Lusi mengandung sinyal geokimia yang berasal dari sistem vulkanik yang dalam (The data highlight that both the HC reservoirs and the Lusi system contain a geochemical signal derived from a deep-seated volcanic system), dimana helium kemungkinan bermigrasi sepanjang patahan bersamaan dengan CO2 (where helium likely migrated along faults together with CO2).

Abstract

Lusi is an ongoing mud eruption in NE Java, Indonesia, that started in May 2006.

This active sediment-hosted hydrothermal system is located in a hydrocarbon-rich back-arc sedimentary basin, only 10 km away from the nearest Holocene volcano.

Three oil and gas fields are located in the immediate vicinity of Lusi (3-5 km to the west, south-west and north-east).

The hydrocarbon (HC) accumulations are confined to shallow volcanoclastic Pleistocene reservoirs at 400-700 meter depth, and the current production is focused on gas, whereas oil was produced earlier.

Sampling of these HC fields was conducted in 2017 within the framework of the ERC Lusi Lab project.

Gases were analyzed by gas chromatography and isotope ratio mass spectrometry.

The results show that the gas is methane dominated, with higher methane homologues present as well, where the carbon and hydrogen isotope values of the methane indicate a thermogenic origin.

Elevated helium isotope ratios (3He/4He) are similar to values from fumaroles of the Welirang volcano, 25 km to the south-west from the study area, suggesting a mantle source of the helium.

Moreover, similar 3He/4He values were measured in the CO2-dominated gas venting from Lusi and from CH4-dominated satellite seeps, demonstrating a lack of correlation between gas speciation and helium isotope ratios.

 The data highlight that both the HC reservoirs and the Lusi system contain a geochemical signal derived from a deep-seated volcanic system, where helium likely migrated along faults together with CO2.