In order to evaluate asphaltene deposition behavior near wellbore region in the reservoir as well as inside the tubing in Minami-Kuwayama field, Japan, a single phase bottom hole sample was devoted to laboratory experimental analysis such as the Asphaltene Deposition Envelope (ADE), molecular weight profile at different pressure/temperature conditions and re-dissolution tests. The attenuation of laser light transmission due to asphaltene precipitation was used to identify the onset pressure of asphaltene precipitation. Once coming across the asphaltene onset pressures, asphaltene deposition volumes significantly increased as the pressures decreased, which was quantitatively evaluated by SARA analysis. Consequently, the ADE was generated based on these experimental results. The asphaltene deposition behavior was estimated by comparing the ADE with measured pressure/temperature profile near wellbore region in the reservoir and inside the tubing. The asphaltenes were separated from the deposits inside the tubing and bottom hole sample using Heptanes. The composition and molecular weight of asphaltenes were obtained using LDI-TOFMS (Laser Desorption Ionization Time of Flight Mass Spectrometer). According to the analysis, the average molecular weight of asphaltenes in the deposits inside the tubing and that in bottom hole sample were 1,400 and 1,290, respectively. The asphaltene in single phase bottom hole sample precipitated by pressure reduction was re-pressurized to test the re-dissolution. The laser light transmission and SARA analysis showed that it was reversible. When the asphaltenes were re-dissolved in the oil sample, the concentration of asphaltenes in the oil increased. In the re-dissolution process, the concentration of low molecular weight component in the asphaltenes tended to increase, and the average molecular weight of asphaltenes tended to decrease. This indicated that high molecular weight component of asphalten were more easily dissolved at early stage, whereas low molecular weight component of asphalten were more hardly and slowly dissolved.
While conventional oil and gas production is expected to hit a peak in dozens of years, the world still requires hydrocarbons as the main source of energy. The need to fill the gap between supply and demand, and the recent high oil price, have aroused enthusiasm for unconventional oil and gas. But, the development of them is, full of ups and downs. The extra heavy oil boom began in early 2000's, when large projects started in Canada and Venezuela. But, rising plant cost, shortage of skilled workers, and environmental concerns have increased uncertainty of those projects, and finally this year global economic crunch and oil price plunge ended the boom. In those circumstances, technologies to reduce production cost are keenly craved and several are on trial in actual projects. In 2005, U.S. Congress directed the Bureau of Land Management to manage oil shale development on public lands. By 2008, the bureau issued six research development and demonstration leases that will allow oil shale development to resume on a 160-acre tract of public land. Currently, in-situ conversion process is arguably the most cost effective recovery method. The U.S. has led the world in coalbed methane (CBM) development, and the production reached 1.8 tcf by 2006. While some countries are after the footsteps of the U.S. in CBM development, the U.S. is now considering giving a higher priority to shale gas instead as the results of efforts to develop economical production methods for years. Japan has studied gas hydrate development since 1990's. In 2008, the Japan Oil, Gas and Metals National Corporation carried out a successful gas hydrate production test in Canada. The next step of their pursuit will include practical application of the production method, nationwide potential evaluation, and development of environmental assessment technique.
The construction of new jackup rig of Japan Drilling Co., Ltd. (JDC) has been completed in June 2008 at PPL Shipyard in Singapore. JDC's new rig named “HAKURYU-10”, a Baker Marine Pacific Class 375 design, is providing its drilling services for ENI offshore Tunisia, North Africa without single serious operation downtime since November, 2008 to date. In this text, we will introduce high specification of HAKURYU-10 to respectable Japanese clients, in the meantime, JDC project team's stressful experience as well as Lesson and Learned from this construction will be briefed.
S-wave information, in conjunction with conventional P-wave, may quantitatively delineate reservoir condition and has progressively been playing important roll in recent oil/gas exploration and development. A reflection seismic method using PS converted waves (PS seismic) is considered one of the most promising approaches to collect S-wave data since it involves P-wave seismic sources instead of costly S-wave sources and the MEMS sensor has been dramatically reducing deployment cost. This expository paper summarizes PS seismic methods in three aspects; principal characteristics of S-wave, basic concepts of PS seismic, and its typical applications in the industry.