Oil exploration has been carried out since 1914 in the Tenpoku Area, Hokkaido. Several oil fields were discovered in the early stage of the exploration. Main producing horizon of those fields was the Masuporo Formation however, all of these fields were minor in their scale bacause of the poor development of sandstone reservoir.
During 1970 to 1975, the fourth five-year-exploration plan was carried out by the Government and three deep wells (MITI stratigraphical wells) were drilled after the basic seismic works in the area. These activities were followed by several seismic survey and two deep wildcats which were carried out by JAPEX.
Based on the results of a frame work of the area, by reviewing available data obtained from the past exploration activities, the authors had some geological considerations for the petroleum exploration of the area and concluded as follows:
(1) The result of the compilling work on the source rock evaluation, which is based on the hydrocarbon, non-carbonate carbon and their ratio, shows that the Wakkanai, Masuporo, Onishibetsu and Chikubetsu Formations have possibilities as oil source. However, data on the maturation are not enough to be discussed on the charactristics of the area in this stage.
(2) Sandstone of the Masuporo Formation is the most possible reservoir rock. The sandstone well develops in the eastern half of the area such as the east of the Horonobe fault, core of the Masuporo anticline and lower part of the Masuporo Formation in the Omagari R-1 well however, in the western half, the sandstone is not well develops in such wells as Okumenashi SK-1, Masuporo SK-1D, MITI Wakkanai, Toyotomi R-1 and MITI Hamayuchi.
(3) Palaeogene formations are missing in the central part of the Kiyokawa uplift where MITI Enbetsu was drilled. It is presumed that there is a higher possibility of the development of coarse clastic rocks in the Miocene formations, especially in the Masuporo Formation, around the Kiyokawa uplift.
(4) Kiyokawa uplift and its surrounding area is located at the margin or near the boundary of the palaeogene sedimentaly basin. It is considered that the area situated on the isoclinal high in the Miocene and the migration of hydrocarbon is expected from both of the Miocene and the Palaeogene sediments.
(5) It is considered that the most of the recognized anticlines have grown up since the Early-Middle Miocene on the base of seismic interpretation therefore, possible hydrocarbon migration is expected in the earlier stage of the sedimentation of the Miocene formations.
(6) The average scale of anticlines in the area is about 5km2 of the clousure, which introduce about 1.3 million kl of oil reserve from the reasonable parametres.
(7) Structures around the Kiyokawa uplift are considered to be prospective, Miocene sequence as main target and Palaeogene to upper Cretaceous sequence as second target. According to the results of the above, the exploration can be extended toward north to the Maruyama anticline via the Horonobe anticline.

抄録全体を表示

Since the MITI NANPORO Well was compreted in 1973, twelve deep wildcats were drilled in the areas of eastern Ishikari, southern Sorachi. western Hidaka and offshore Hidaka. Subsurface geologic data, especially of the Takinoue Formation and the Poronai Group, were added by these wells. Based on these data, stratigraphy and correlation were discussed particularly on the pyroclastic sequences, from which no foraminiferas were found.
It is concluded that the pyroclastics in interval between 3, 195.2 and 3, 997.5 metres of the MITI NANPORO well is correlated to those of the Takinoue Formation, seen in the wells of YUFUTSU SK-1 and TOMAKOMAI-OKI A-1.

抄録全体を表示

セメント-砂人工コアとべレア砂岩コアを用いて水およびポリマー溶液による油の回収実験を行なった。コア試験は流れが直線的であるが実際の油層の流れは3次元である。このように流れの様子が異なるので水攻法等の計画に必要な3つの効率のうち接触効率に相当するものしかコア試験から直接得ることはできない。最も重要な効率である面積掃攻率は易動度比に関係する。この易動度比はコア試験により得られる。ポリマー溶液のような非ニュートン流体の易動度は,多孔質体内の非ニュートン流動理論が発達するまではコア試験により求めざるを得ない。ポリマー溶液圧入条件の設定,ポリマーの岩石への吸着,圧入施設の設計等の問題の解決もコア試験に頼らざるを得ない問題である。この他ポリマーの性能評価もコア試験の大切な役割の1つである。ポリマー溶液圧入法のこれらの問題すべてに触れることは実験設備等の制約により難かしく,本実験は置換効率の面に重点を置いて行なわれた。本実験のまとめを以下に記す。
(1) セメント-砂人工コアとべレア砂岩コアを用いた。ポリマーは三洋化成化学(株)製のTSU-330であり,清水に0.01%の濃度で溶解した。
(2) ポリマー溶液圧入法は水圧入法に比べて油の回収を促進し,少ない圧入量で高い回収率を達成できるが,残留油飽和率には影響を与えない。
(3) ポリマー溶液の圧入には水の圧入に比べて高い圧入圧を必要とする。
(4) ポリマー溶液の圧入は水飽和率が低いほど効果がある。
(5) ポリマー溶液の適量を水圧入の間に挾んで用いることによりポリマー量当りの増油量を増加できる。ポリマー溶液量は0.1PV位でも効果があった。
(6) ポリマー溶液圧入により水圧入に比べて易動度比を5倍位改善できた。
(7) ポリマー溶液圧入により水の易動度を3倍位改善できた。
(8) コア試験の意義を高めるには(相対)易動度を測定することが必要である。このためには実験上の処理として,圧入液体中の不純物の除却,圧力の正確な測定が必須であり,相対浸透率曲線および使用液体に対する全相対易動度曲線を作ることが必要である。

抄録全体を表示