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65 巻 , 5 号
選択された号の論文の11件中1~11を表示しています
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  • 浅井 忠一郎, 加藤 透, 重松 英一郎, 石田 浩三, 栃川 哲朗, 三品 哲, 松澤 三朗, 今野 淳, 中村 元
    65 巻 (2000) 5 号 p. 391-392
    公開日: 2008/03/27
    ジャーナル フリー
  • 中村 元, 中村 常太
    65 巻 (2000) 5 号 p. 393-402
    公開日: 2008/03/27
    ジャーナル フリー
    The traditional casing design method for Japan Petroleum Exploration Co., Ltd. (JAPEX) was based on specific margins (either ratios or differences) between the anticipated load and the strength of the casing. The specific margins, however, had never been explained as to the downhole conditions on which the margins are based. The size of the margins had been accepted by the company engineers without reasonable explanations.
    In the mid-1980's, when JAPEX drilled a 6, 000-m Japanese record depth well, the triaxial stress design method was studied. However, due to its relative complexity, the triaxial stress design method was utilized only for some special cases to confirm the soundness of the traditional design.
    In 1989, JAPEX decided to disuse the traditional design method and adopted a new design method. The new design method assumes specific downhole conditions for each part of the design, namely collapse, burst and tension. Design factors were adopted from a combination of the JAPEX traditional design method and the Maximum Load Casing Design method presented by Mr. C. Prentice.
    Through the repeated field use since then, the new JAPEX method has been modified to better reflect the downhole conditions and to reduce casing cost. Application of different sets of design scenarios to exploratory wells and development wells is an example of such modifications.
    In the future, the concept of probabilistic distributions of the strength and the load of the casing shall be introduced in casing design. This approach will quantify the risk of casing failures and will provide a new methodology to preserve an acceptable level of safety without sacrificing economic considerations.
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  • 齋藤 清次, 佐久間 澄夫
    65 巻 (2000) 5 号 p. 403-416
    公開日: 2008/03/27
    ジャーナル フリー
    A 540°C, 3, 729m geothermal well, WD-1A, was drilled in Kakkonda, Japan. One major issue for drilling high temperature wells was how to protect temperature sensitive downhole tools from high temperature stagnant mud while RIH (Running-in-the-hole). To solve this problem, a TDS (Top-drive-drilling-system)-Cooling-Method was developed to drill the WD-1 A well. With this method, mud was pumped continuously while running a BHA (Bottom-hole-assembly) into the hole using a TDS. To evaluate this TDS-Cooling-Method, an experiment was conducted and discovered to be very effective for cooling BHAs while RIH.
    Bit performance for two geothermal wells, drilled with and without using the TDS-Cooling-Method, was evaluated and revealed that the TDS-Cooling-Method could prolong three-cone bit life 5times. Also, economic evaluation of using the TDS-Cooling-Method was made based on the field data. More than a 40% cost reduction was simulated by using the TDS-Cooling-Method when drilling the bottom 1, 000m section of a 3, 500m well.
    Several deep, high-temperature oil wells, with bottom hole static temperatures ranging from 180 to 230°C, have been drilled since 1990 in Japan by MITI. Reports are that bit life decreased to 15 to 30 hours, when the deeper sections of these wells were drilled. Bit performance of the MITI-Nishikubiki well was surveyed and judged that o-rings were damaged while RIH due to high temperatures. Judging from the WD-1A case, the TDS-Cooling-Method was considered to be a possible solution method to prolong the bit life. Economic evaluation of the use of TDS-Cooling-Method was made for the MITI-Nishikubiki well and determined that a 56 million yen cost reduction could be achieved by using the TDS-Cooling-Method if applied for the last 600m section.
    TDS-Cooling-Method can be expected to extend the use of temperature sensitive tools and prolong their life for both geothermal and oil wells. Therefore, even greater cost savings can be expected in addition to those simulated.
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  • 山本 晃司
    65 巻 (2000) 5 号 p. 417-429
    公開日: 2008/03/27
    ジャーナル フリー
    The importance of borehole instability has been acknowledged as one of the main causes of unproductive time and reduction of drilling performance in the oil industry. Recent intensive studies on borehole instability in some regions have shown the successful applications of geomechanics to borehole instability in the overthrust region. TRC/JNOC has started a research program to establish a comprehensive scheme to tackle important but scientifically complex phenomenon. Many physical and chemical processes are related to the mechanical behavior of the formation surrounding wells during and after drilling. Also, the establishment of a geomechanics model for deep underground is an important and difficult subject of this study.
    In this paper, the author presents the basic concept of the borehole failure mechanism, recent advances of such studies including realistic constitutive laws, failure criteria, poroelastic treatment for low permeable rocks and a discrete model of rock mass failure. The importance of the geomechanical model for this problem is discussed, and the results of an investigation results of drilling troubles caused by borehole instability in Japanese fields are presented.
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  • 吉田 肇
    65 巻 (2000) 5 号 p. 430-438
    公開日: 2008/03/27
    ジャーナル フリー
    Iwaki Platform was built in 1984, which is located about 40 km off the east coast of Fukushima prefecture, and natural gas has been produced from C-Structure for 15 years. There are a few Satellite fields toward the south-south-west from the platform, which is called C-Satellite North, C-Satellite Central and C-Satellite South and those approximate distances from the platform is 4km, 6km and 7.5km each.
    Johban Oki-2 well was drilled to C-Satellite North structure as the first extended reach well in Japan and completed successfully in 1994. After the success of the well, some engineering study mainly regarding rig modification was done for the next ERD to C-Satellite Central structure, however the detail engineering and the execution had been temporarily given up for the various reasons.
    From the end of 1998, feasibility study of the ERWs to both C-Satellite Central structure and C-Satellite South structure was conducted as the alternative development instead of subsea completion. The FS covered preliminary drilling engineering, structural analysis of drilling structures and rig modification, and the FS took almost nine months. After all, the execution was totally given up mainly due to the difficulties of the rig modification and reinforcement. This paper reports the critical issues of drilling engineering in this study, 1) well path design, 2) hole cleaning, 3) torque & drag and mud friction, and 4) borehole stability, which will match the subject “The Integration of Technology and Engineering” of the 2000 JAPT Drilling Symposium.
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  • 川村 和広, 市川 祐一郎, 江 俊賢, 江守 稔, 上村 義則, 中村 元
    65 巻 (2000) 5 号 p. 439-449
    公開日: 2008/03/27
    ジャーナル フリー
    A downhole temperature, and pressure simulation program for drilling, especially for safe methane hydrate drilling, has been developed under a joint R & D project led by Japan National Oil Corporation. The simulation program integrates a database management, a numerical computation core, and a graphical user interface (GUI) in a Windows-based application. It aims to support the control of methane hydrate drilling by simulating wellbore temperature and pressure simultaneously. Three key models are employed in the computation core, 1) a one-dimensional flow dynamics model, 2) a two-dimensional heterogeneous heat conduction model, and 3) a wellbore-formation interface model.
    New features in the development include, 1) computation of circulating temperature profiles of not only the wellbore but also radially in the formation, 2) the ability to show the in-situ P-T conditions and hydrate equilibrium curve simultaneously, 3) use of multiple heat transfer correlation and rheology model options, 4) ability to simulate heat transfer in a marine riser including buoyancy modules, 5) capability to simulate environmental effects, such as current, sea temperature, etc., and 6) friendly GUI.
    The validation and verification (V & V) have been performed using field data. The comparison showed a good agreement based on the return and downhole circulating temperature and standpipe pressure. After the work of V & V, the simulation program has been successfully applied in the planning of, and during the drilling of the Japan MITI methane hydrate exploratory well“NANKAI TROUGH”.
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  • 鎌田 正博, 笠松 隆幸
    65 巻 (2000) 5 号 p. 450-458
    公開日: 2008/03/27
    ジャーナル フリー
    掘削同時地震探査法(Drill-Bit Seismic While Drill-ing)は,陸上,海洋での作井で長年使用され,その作井にかかる費用の削減と掘削中の危険防止に貢献してきた。この技術は,ドリルビットが発生する掘削音を地震探査の音源として,地上に設置されたセンサーで信号をとらえるもので,通常のVSPの震源とレシーバーの位置を入れかえただけだが,ノイズの多い地上にレシーバーがあるので,数々の信号処理を行うことにより,作井にかかわる貴重な情報を掘削中に提供する。
    この技術は,時間と深さ関係,地層の音速を測定し,掘削中にドリルビットの位置を地震探査図の時間軸を深度に変換し,その上に示すものである。VSP画像処理を使ってドリルビットの前方を示し,異常高圧層にビットが接近していることをモニターすることができる。これは,作井費用を削減し,危険防止に貢献する。
    近年,海底センサーアレイは500mの水深まで展開でき,イシドネシアの沖で水深480mの軟弱層の掘削に用いられ,ケーシングを予定していた地層の境に設置することに貢献した。
    さらにこの技術を3,000mの大水深掘削に適応するため,OCCの協力を得て,垂直けい流用のケーブルを開発した。このケーブルには,海流により誘起されるヴォルテックスを防止するため,特殊なフェアリングが施されている。ヴォルテックスは海流によるケーブルにかかる力を増大し,信号の計測に悪影響を及ぼす雑音になる。この技術はメキシコ湾で水深1,280mの海底油田開発で使用された。時間と深さ関係は,.ローラーコーンビットを使った軟弱層の掘削で3,810mまで測できた。
    このような情報は掘削前の地層の地震波音速構造を作井中に校正することができ,掘削前の深度の推定の違いによって突然異常高圧層に出会うような,予測できない事態を防止することに貢献する。
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  • 栃川 哲朗, 中村 元, 鎌田 正博, 増田 昌敬, 齋藤 清次, 吉田 肇, 山本 晃司, 川村 和広
    65 巻 (2000) 5 号 p. 459-466
    公開日: 2008/03/27
    ジャーナル フリー
  • 浅井 忠一郎
    65 巻 (2000) 5 号 p. 467-468
    公開日: 2008/03/27
    ジャーナル フリー
  • 山本 正伸, 田口 一雄
    65 巻 (2000) 5 号 p. 469-476
    公開日: 2008/03/27
    ジャーナル フリー
    秋田県矢島地域の新第三系女川層•船川層ビチュメンと猿倉原油の窒素官能基を非水滴定法により強塩基性窒素(ピリジン態窒素),弱塩基性窒素(主にアミド態窒素),非塩基性窒素(ピロール態窒素と非反応性窒素)に分けて定量した。一次生産性が高かったと考えられる層準で,高い強塩基性窒素量が認められた。この含有量が古一次生産力に関連している可能性が考えられる。また,強塩基性窒素の全窒素に対する割合はビチュメンよりも原油のほうが高い。この違いの原因として,熟成度の違いと石油移動に伴う分別の両者の可能性が考えられた
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  • 佐藤 光三, 武田 秀明
    65 巻 (2000) 5 号 p. 477-488
    公開日: 2008/03/27
    ジャーナル フリー
    水圧破砕で形成されるフラクチャーの形状を改善するつめの一手法として,穿孔区間の制限が提唱されている。しかし法がら,通常の坑井で広く認識されているように,この手法は生産性の低下を招きうる。フラクチャーの形成された坑井で,この低下がどの程度のものであるかを把握するために,シミュレーションによるケーススタディーを実施した。
    本研究により,以下の点が明らかと法つた。す法わちぢ,非ダルシー流が支配的で法い限り,部分仕上げはフラクチャー坑井の生産性を著しくは低下させず,したがって,油井に対しては穿孔制限をすることに問題はない。また,フラクチャーが十分に長く広ければ,非ダルシー流であっても部分仕上げによる生産性低下はさほど大きくない。しかしながら,フラクチャー形状の改善が達成され法い場合,穿孔制限は非ダルシー流の下で顕著な生産性低下を招きうる。そのよう法場合に取りうる対処法としては,未穿孔区間への再穿孔が有効である。非ダルシー流の影響を緩和するためには,生産区間全体にわたる流量の均等化が重要である。
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