For accelerating asphaltene evaluation, a commercial packaged apparatus applying laser light scattering technique was installed in our laboratory in 2010. This apparatus can measure asphaltene onset pressure (AOP), count/size of precipitated asphaltene particles and density/viscosity. During isothermal de-pressurizing test, AOP is detected by mainly using solid detection system (SDS) equipped in the apparatus. The SDS consists of laser light source, receiver, and glass cell. Measuring by SDS provides continuous profile for power of transmitted light (PTL) that can typically show a sudden drop when asphaltene particles start precipitating. However, our laboratory experience is sometimes faced to untypical PTL profiles. This paper focused on a case that did not detect SDS-basis AOP for a single phased fluid from domestic oil field. To find a way for solution, it was applied to estimate AOP by comprehensively interpreting whole measured data (i.e. particle count/size, density and viscosity) that were simultaneously taken at the SDS application. As a result, appropriate and practical AOP was estimated successfully.
アフガニスタンにおいては, 北部に位置するアム・ダリア堆積盆地とアフガン―タジク堆積盆地で炭化水素の存在が確認されており, 最も高い炭化水素ポテンシャルを持つと考えられている。本研究は, アム・ダリア堆積盆地の2つの油田において, 原油分析データの定量的な解析に基づいて根源岩を推定する初の試みである。アム・ダリア堆積盆地のアフガニスタン側の油田で原油試料を採取し, 原油一般性状, 軽質炭化水素組成, バイオマーカー組成, 炭素同位体組成を分析した。
本研究により, 採取した原油試料が還元環境で堆積した海成の有機物起源であることが, 原油中のノルマル・アルカンやイソプレノイド化合物の組成から判明した。さらには, 油生成帯初期の根源岩から生成したこと, 微生物による分解を受けていないことにも明確になった。アム・ダリア堆積盆地の地質情報と炭素同位体組成などの地化学分析結果を総合的に考察した結果, ジュラ紀の炭酸塩岩が原油の根源岩であると推定することができた。
The exploration well named METI Joetsu Kaikyu (JX) was drilled in the “Buri” structure in the Joetsu Basin from April through July, 2013. The “Buri” structure is located in the Joetsu Knoll at the eastern edge of the Sea of Japan, offshore Niigata Prefecture, Japan.
This well reached down to 3,110mMDBRT and confirmed the Haizume, Nishiyama, Shiiya (Pliocene), Upper Teradomari (Upper Miocene) and Lower Teradomari (Upper Miocene) Formations. Those formations were mainly composed of interbedded sandstone and mudstone with minor tuff. Four key beds, “P tuff”, “Q tuff”, “S tuff” and the fossil marker of “Blue Zone” which are identified in the Niigata Basin were also recognized in this well.
Several hydrocarbon shows were encountered in the target sections between the Shiiya and Lower Teradomari Formations. The methane gas shows were observed in the main part of the Shiiya Formation without any oil shows. Several minor oil and gas shows were encountered between the basal part of the Shiiya and Lower Teradomari Formations.
Although the hydrocarbon accumulations have not been discovered, valuable subsurface information such as stratigraphy, geochemistry and rock properties has been acquired in the well, which contributes to a further understanding of the petroleum system and future hydrocarbon exploration in the Joetsu Basin.
A method for the determining of solubility of methane and carbon dioxide in high-pressure water was developed by direct injection of the sample into a gas chromatograph column. Solubility was determined from the values obtained from the absolute calibration curve. This is a simple and quick method replacing a conventional method (flash method). Solubility of CH4 and CO2 was measured by this method and the high accuracy was confirmed compared to acquired data by flash method.