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Volume 78 (2013)
- Issue 6 Pages 445-
- Issue 5 Pages 354-
- Issue 4 Pages 295-
- Issue 3 Pages 243-
- Issue 2 Pages 125-
- Issue 1 Pages 5-
Volume 78, Issue 6
Displaying 1-10 of 10 articles from this issue
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Lecture
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Sumihiko Murata, Akihisa Ashida, Satoru Takahashi, Hiroshi Okabe2013 Volume 78 Issue 6 Pages 445-454
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSIn-depth profile modification, that is blocking the already swept high permeable zones in a reservoir with a gelling agent, would be one of the most effective sweep efficiency improvement (SEI) methods.
Firstly, in this paper, gelling agents developed for the in-depth profile modification are reviewed in order to understand their present situation and problems. Then, it is shown that TAP (thermally active polymer), PPG (preformed particle gel), CDG (colloidal dispersion gel) are suitable for the in-depth profile modification and overcome the difficulties of in-situ gelation, but they still have limitations in the applicable range of pH, temperature, pore throat diameter, and so on.
Secondly, a visualization experiment of the in-depth profile modification performed to a multilayered reservoir model, in which high permeable formations and low permeable formations are alternate, is shown to confirm the effect of indepth profile modification on SEI and oil recovery. Moreover, the problem that the injected water bypasses the blocked zones in high permeable formation from the low permeable formations and the 100% of sweep efficiency is quite difficult to be achieved is shown.
Finally, following results of the numerical simulations conducted to thirty-two heterogeneous reservoir models under the several blocking conditions are shown. The effect of in-depth profile modification on SEI increases with the increase in the volume of gelling agent and the decrease in the volume of chase water. But, in this case, the bottom-hole pressure increases and the risk to cause a severe formation damage or to make a fracture increases. Furthermore, the effect of in-depth profile modification on SEI increases with the increase in the vertical heterogeneity, and the horizontal heterogeneity is less correlated to the effect than the vertical heterogeneity when the heterogeneity indexes, Dykstra-Parsons coefficient and correlation length, are in the range set for this study.View full abstractDownload PDF (1744K) -
Yuichi Sugai2013 Volume 78 Issue 6 Pages 455-462
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSMicrobial EOR (MEOR) is generally understood as one of other EOR techniques although its high potential has been shown through numerous investigations for almost 90 years. The author concludes that the following three challenges should be needed to develop MEOR to a practical EOR.
· Screening for potential microorganisms that can grow under reservoir conditions such as high temperature and high salinity
· Development of commercial MEOR simulator
· Developing real-time sensing system to monitor the target microorganism in reservoir
The author has isolated successfully a thermophilic anaerobe that can degrade long-chain hydrocarbon of crude oil selectively and reduce oil viscosity to 60 percent of its original viscosity after a few days' incubation. It can grow even under a temperature of 80°C and a salinity of 90 g/L. The potential of MEOR using this anaerobe was shown through core-flood experiments.
The author has developed a prototype numerical simulator for MEOR that consists of 5 compositions: degraded oil, undegraded oil, brine, oil-degrading anaerobe, and yeast extract. The growth of the anaerobe depends on the concentration of yeast extract, temperature, and salinity on this numerical model. According to the numerical experiments, growth of the anaerobe and reduction of oil viscosity were found only around the injection well because the anaerobe consumed whole yeast extract around there. Therefore, the recovery factor can be increased by increasing the amount of yeast extract injected.
The author is estimating a possibility of a novel real-time sensing system based on the flow cytometry in order to monitor the target microorganism in reservoir. A target microorganism could be found selectively in culture solution where the target and nontarget microorganisms mixedly exist using a commercial flow cytometer, therefore, the possibility of the sensing system based on the flow cytometry was shown.View full abstractDownload PDF (1352K) -
Yohei Kawahara, Mutsuto Takagi, Nguyen Chu Chuyen, Atsushi Hatakeyama, ...2013 Volume 78 Issue 6 Pages 463-468
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSThe Lower Miocene sandstone reservoir in Rang Dong Field, within Block 15-2 offshore Vietnam, has continuous oil production since 1998. Since achieving peak rates in 2002, oil production has steadily declined despite efforts to improve oil recovery. Numerous production improvement techniques were studied with focus on the potential applications of hydrocarbon gas enhanced oil recovery (HCG-EOR). Initial feasibility studies on HCG-EOR indicated potential applicability to addressing the production decline.
The HCG-EOR Pilot Test program, designed with appropriate monitoring plan, was implemented in 2011 coupled with a water-alternating-gas (WAG) scheme. The HCG-EOR pilot test yielded positive EOR impacts such as oil rate increase and water cut reductions concurrently with oil property changes. Reservoir saturation logging on a well between an injector and a producer indicated reduction in residual oil saturation, which is encouraged by injected gas encroachments, in multiple layers. These observations are considered positive indications of the effectiveness of HCG-EOR in a field scale application.
This paper presents the initial feasibility study results, the field findings to date of the HCG-EOR Pilot Test including designs, monitoring plan, results, and the post evaluation toward achieving the HCG-EOR full field scale implementation.View full abstractDownload PDF (1890K) -
Masanori Kurihara2013 Volume 78 Issue 6 Pages 469-481
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSUnconventional oil and gas attract attention as next generation energy, because of their vast amount of resources. A part of the unconventional oil and gas has been already produced on a commercial scale, while the development of some of them is still in the stage of research. This paper first reviews the methodologies for producing unconventional oil and gas, which are already utilized on a commercial basis or are considered to be promising in the research stage. It is, then, introduced how the existing production methods are being improved/modified to increase the productivity of unconventional oil and gas.
In the development of heavy oil/extra heavy oil/bitumen, advanced production methods including the combination of steam and solvent injection as well as the in-situ upgrading are investigated besides conventional steam injection and in-situ combustion. In the shale gas/oil exploitation, it is well-known that the improvement and integration of horizontal well, multi-stage hydraulic fracturing and micro-seismic technologies have made it possible to dramatically increase the production rate. However, the area of high productivity, which is called a ‘sweet spot,’ is confined to small parts of a formation. Toward the identification of this sweet spot, there is a variety of research work conducted, including the examination of the effects of reservoir properties such as natural fracture permeability, matrix permeability and hydraulic fracture length on gas/oil production, and the investigation of the fluid flow mechanism through micro organic pores. The research work for the development of methane hydrate has started recently. Although the superiority of the depressurization method over other methods such as thermal methods has been revealed, the recovery of methane by depressurization is expected to be not more than 50-60%. The methodologies that can be applied in conjunction with and/or after depressurization are being pursued.View full abstractDownload PDF (1836K) -
Noriaki Watanabe, Takuya Ishibashi, Noriyoshi Tsuchiya, Tetsuya Tamaga ...2013 Volume 78 Issue 6 Pages 482-490
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSWe explore the three-orders-of-magnitude difference in productivity between two wells, observed at the Yufutsu oil/gas field in Hokkaido, Japan. A highly reliable discrete fracture network (DFN) model for this field was previously constructed by integrating 3-D seismic data, well logging data, in-situ stress data, and acoustic emission data during a massive hydraulic injection. However, the huge difference in well productivity was not reproduced even with the highly reliable DFN model. In the present study, different from previous studies, scale-dependent fracture aperture distributions are numerically determined by using pairs of fractal fracture surfaces, and given to the critically stressed fractures in the DFN model. For this DFN model with the aperture distributions, fluid flow simulations are conducted by using a novel simulator, GeoFlow, which has been recently developed by the authors to predict the 3-D channeling flow (formation of preferential flow paths) in a rock fracture network. In the GeoFlow simulations, the huge difference in well productivity, which is never reproduced by conventional DFN simulations with the parallel plate model for fracture flow, is successfully reproduced. It is indicated that, in reality, fluid flow within a fractured reservoir is much more localized than a prediction by the conventional DFN simulation, due to the formation of preferential flow paths, which is likely to impact well productivity. It is therefore desirable to evaluate a distribution of preferential flow paths in a fractured reservoir with the concept of GeoFlow.View full abstractDownload PDF (3501K) -
Ryohei Kamitsuji, Yusuke Kumano, Satoru Yokoi2013 Volume 78 Issue 6 Pages 491-495
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSAyukawa oil and gas field is located in Akita prefecture, Northern part of Japan. In the field, we have frequent and intensive oil show through the Onnagawa shale, which is Miocene, bio-siliceous and known as the main source rock in Japan. Onnagawa is considered to be similar to Monterey shale. Acidizing in Monterey shale has a long history of success. Though the production is generally improved by removing the drilling and completion damage, unexpected favorable responses from low permeability rock are also reported. These improvements are considered to result from dissolving the calcite and clay minerals in natural fractures and enhancing the wellbore connection into natural fracture network. The acid stimulation test was conducted to verify this acidizing effect in Onnagawa shale. The target well showed very low productivity. Weakly fracture distribution is detected from wellbore images. No skin damage and low permeability on the order of 0.01 md were estimated from the pressure analysis. So the objective of this stimulation is not the removal of drilling and completion damage, but the improvement of natural fracture conductivity. The stimulation program was comprised of three stages that alternated 15% HCl preflush, 12% HCl + 3% HF main acid, NH4Cl overflush, and particulate diverting agent. The significant pressure drops indicating the injectivity improvement were observed during both preflush and main acid injection. The oil production dramatically increased from 1.5 kl/day to 50 kl/day. The productivity index also increase from 0.3 kl/day/MPa to 45 kl/day/MPa. This test is the first successful stimulation of the tight oil formation in Japan.View full abstractDownload PDF (1038K) -
Takaaki Uetani2013 Volume 78 Issue 6 Pages 496-499
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSThe Minami Kuwayama field, one of the largest oil fields in Japan, began production in 2003. Severe asphaltene problems have been experienced in all wells, in both the reservoir and production tubing, and at the surface facilities. We have been operating this field for over 10 years and learned that we could sustain the productivity through the use of chemicals and the control of production rates. This article provides our experience and major findings.View full abstractDownload PDF (1020K) -
Kodai Kato, Kenji Endo, Hiroyuki Nakagawa, Tsuneta Nakamura2013 Volume 78 Issue 6 Pages 500-505
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSHANGINGSTONE oil sands field is approximately 50 km away from Fort McMurray, Alberta province. Japan Petroleum Exploration has been producing bitumen (oil) from this field by SAGD method through overseas subsidiary, Japan Canada Oil sands for over a decade. SAGD stands for Steam Assisted Gravity Drainage and steam is injected into oil sands reservoir to decrease the viscosity of bitumen in this process, while mobile oil is produced by the gravity force simultaneously. The production performance of SAGD is significantly affected according to geological heterogeneities and reservoir parameters such as permeability. Therefore, highly detailed geological models have been constructed to evaluate the production performance, operation strategies and new technologies applied to future green fields. Simulation approaches are considered of value in terms of its flexibility. Although base work flow of our simulation approach has been established in this work, a couple of parts of the work flow need to be brushed up further to make it applicable to future evaluations.View full abstractDownload PDF (1318K)
Original Article
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Vitsarut Attavitkamthorn, Javier Vilcáez, Kozo Sato2013 Volume 78 Issue 6 Pages 508-519
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSMetamodeling is a powerful tool used to create analytical relationships between input parameters and reservoir simulation responses. Once created, these analytical relationships called metamodels can be used instead of time consuming and costly reservoir simulations. This research explores the feasibility of using metamodeling for the assessment of gas flooding Enhanced Oil Recovery (EOR) in Pattani basin where performing individual simulations for thousands of reservoirs is practically impossible. Two types of metamodels were created, a parametric and a nonparametric metamodel. The parametric metamodel was created using design of experiment techniques and regression analysis, whereas the non-parametric metamodel was created using alternating conditional expectations and local linear smoother fit with varying window width. Monte Carlo simulations using actual field data were performed to verify both, the created metamodels and the strategy adopted in this study to complete the fluid and petrophysical properties data required to perform reservoir simulations. Based on the results obtained using the created metamodels, it is concluded that Double Cycle Water Alternating Gas (Double Cycle WAG) injection is the best gas flooding EOR method when CH4 is used. This method provides a 4.4% of Original Oil in Place (OOIP) incremental oil recovery over waterflooding. Whereas, when CO2 is used instead of CH4, Simultaneous Water Alternating Gas (Simultaneous WAG) injection is the best gas flooding EOR method. This method provides a 7.8% of OOIP incremental oil recovery over waterflooding. Our results prove the feasibility of using metamodeling to deal with thousands of reservoirs under lack of detailed data on fluid and petrophysical properties of reservoirs of Pattani Basin.View full abstractDownload PDF (1371K)
Glossary
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Masaki Daitoh, Norihito Inada2013 Volume 78 Issue 6 Pages 520-523
Published: 2013
Released on J-STAGE: April 03, 2015
JOURNAL FREE ACCESSIn 1997, JNOC (the present JOGMEC) introduced the drilling simulator DS-5000 Classic in Kashiwazaki Test Field. This simulator is used for training school on well control, and this training can lead to the issuance of an IADC WellCAP certificate. The simulator can reproduce an environment similar to that in actual drilling operations and is useful for accident prevention as well as personnel training. However, because the DS-5000 has been in operation for ten years or more, various problems (such as loose connections) have been occurring. Therefore, we decided to overhaul and revamp the equipment and upgrade the software of the DS-5000. In addition, we introduced a new simulator, the DS-600. The DS-600 imitates an automated control system, which is being applied in the latest drilling rigs. From now on, we are planning to use these two simulators for new training courses besides those on well control.View full abstractDownload PDF (1218K)
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