利用深井岩心探討岩性及構造作用對碎屑沉積岩孔隙率和滲透率之影響

楊盛博(Sheng-po Yang)

指導教授 ： 董家鈞

國立中央大學/地球科學學院/應用地質研究所/碩士(2015年)

摘要

對於岩體而言，孔隙率與滲透率是決定地下流體富集與移棲之關鍵因素，然而岩體會受沉積環境與構造作用而產生不同之孔隙率與滲透率。故本研究利用高圍壓孔隙率/滲透率量測儀(YOKO2)量測沉積岩隨有效圍壓變化下之孔隙率和滲透率、觀察岩石薄片及岩石粒徑分析，探討岩性與構造作用對岩石孔隙率與滲透率之影響。本研究使用之試體取自台西盆地南側彰化濱海地區之台灣電力公司TPCS-M1鑽井，為受大地構造影響較低之地區，而試體所屬地層為中新世至更新世。利用其試驗結果，相較於受構造抬升作用影響較大之台灣車籠埔斷層深井鑽探計畫(Taiwan Chelunpu-fault Drilling Project, TCDP)鑽井的岩心試體。結果顯示因岩性與受到構造作用的程度之差異，使得TCDP與TPCS-M1砂岩類之孔隙率及滲透率為粒徑組成、膠結程度與微裂隙密度所控制。然而，TCDP砂質岩類孔隙率與滲透率高於黏土含量較高及微裂隙密度較低之TPCS-M1砂質岩類(孔隙率差距約2 - 5%；滲透率差距約兩個數量級)，卻低於膠結較差之TPCS-M1砂質岩類(孔隙率差距約3 - 7%；滲透率差距約一至兩個數量級)。另外，TCDP泥質岩類之孔隙率及滲透率，均低於TPCS-M1泥質岩類(孔隙率差距約8%以內；滲透率差距約一至三個數量級)，原因可能與砂含量和岩石之原始埋藏深度有關。

關鍵字

岩性 ； 構造作用 ； 碎屑沉積岩 ； 孔隙率 ； 滲透率

並列摘要

The porosity and permeability of rocks are important parameters for the storage and migration of underground fluids in formations; however, rocks are affected by depositional environment and tectonization and then the porosity and permeability will be changed. The objective of this study is to discuss the effect of lithology characters and tectonization on permeability and porosity of rocks, so this study use the porosity/permeability measurement system(YOKO2) to measure the permeability and porosity of siliciclastic sedimentary rocks, and analyze the thin-sections of core samples and grain size distribution. The tested samples are siliciclastic sedimentary rock from Miocene to Pleistocene of TPCS-M1 with the low degree of tectonism, in the west of Taiwan, and to contrast with TCDP (Taiwan Chelunpu-fault Drilling Project, TCDP), which is on the structure uplift. The experimental results indicate that porosity and permeability of TCDP and TPCS-M1 sandstone is controlled by particle size composition, cementation and microfracture density. However, the porosity and permeability of TCDP sandstone are higher than that of TPCS-M1 arenite with high content of clay and low microfracture density, the differences in porosity and permeability resperctively are about 2 - 5% and two orders, but lower than that of TPCS-M1 arenite with weak cementation, the differences in porosity and permeability respectively are about 3 - 7% and one or two orders. Moreover, the reason for the porosity and permeability of TCDP argillaceous rocks are lower than TPCS-M1 is related to sand content and original buried depths, the differences in porosity and permeability resperctively within about 8% and one or three orders.

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