陳美玲, 潘仁芳, 張超謨, 沈祿銀

(長(zhǎng)江大學(xué) 油氣資源與勘探技術(shù)教育部重點(diǎn)實(shí)驗(yàn)室，武漢 430100)

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濟(jì)陽拗陷沙河街組頁巖與美國Bakken組頁巖儲(chǔ)層“甜點(diǎn)”特征對(duì)比

陳美玲, 潘仁芳, 張超謨, 沈祿銀

(長(zhǎng)江大學(xué) 油氣資源與勘探技術(shù)教育部重點(diǎn)實(shí)驗(yàn)室，武漢 430100)

從源巖到儲(chǔ)層的思路，探討濟(jì)陽拗陷沙河街組頁巖和美國Bakken組頁巖儲(chǔ)層特征和形成機(jī)理。通過對(duì)Bakken組和沙河街組頁巖有機(jī)地球化學(xué)分析、巖性分析、儲(chǔ)層物性分析和礦物學(xué)分析，表明沙河街組頁巖儲(chǔ)層“甜點(diǎn)”特征為：有機(jī)質(zhì)以Ⅰ型干酪根為主；wTOC>2.36%，Ro為0.76%～0.90%；主要為紋層狀泥灰?guī)r、泥質(zhì)白云巖、灰質(zhì)泥巖、油泥巖和油頁巖；孔隙度>3%，滲透率<0.5×10-3μm2；脆性礦物質(zhì)量分?jǐn)?shù)>20%；含油飽和度為60%～90%；儲(chǔ)層厚度為13.60～90 m；儲(chǔ)層主要為沙三下亞段。對(duì)比Bakken有利頁巖儲(chǔ)層地質(zhì)特征表明，Bakken組頁巖儲(chǔ)層“甜點(diǎn)”特征為：有機(jī)質(zhì)以Ⅰ型干酪根為主；wTOC>5.36%，Ro為0.51%～0.72%；砂質(zhì)白云巖；孔隙度>3%，滲透率<0.1×10-3μm2；脆性礦物質(zhì)量分?jǐn)?shù)>50%；含油飽和度為50%～71%；儲(chǔ)層厚度為3.10～12.20 m；Bakken中段為優(yōu)質(zhì)儲(chǔ)層段。沙河街組和Bakken組頁巖儲(chǔ)層形成的機(jī)理主要為有利的礦物組合和普遍發(fā)育的超壓。

濟(jì)陽拗陷；威利斯頓盆地；沙河街組；Bakken組；頁巖油；儲(chǔ)層特征

隨著世界能源需求的增加，頁巖氣勘探和開發(fā)不斷深入發(fā)展，與此同時(shí)，世界很多地區(qū)已經(jīng)發(fā)現(xiàn)頁巖油，展示了巨大的資源潛力[1-5]。美國是最早從頁巖氣轉(zhuǎn)移到頁巖油勘探和生產(chǎn)的國家，中國頁巖油的開發(fā)剛剛起步。北美學(xué)者認(rèn)為頁巖油是指儲(chǔ)存在富有機(jī)質(zhì)泥巖或頁巖和鄰近貧有機(jī)質(zhì)碳酸鹽巖夾層中的石油[2]。國內(nèi)大多數(shù)學(xué)者認(rèn)為頁巖油是指以吸附或游離態(tài)賦存于納米級(jí)孔喉和裂縫中的石油，或是鄰近的致密碳酸鹽巖夾層的儲(chǔ)集層中，未經(jīng)過長(zhǎng)距離運(yùn)移的連續(xù)型石油聚集，是中國未來非常規(guī)石油發(fā)展的潛在領(lǐng)域[6-10]。

美國威利斯頓盆地Bakken組和中國渤海灣盆地古近系沙河街組頁巖均以富有機(jī)質(zhì)烴源巖和低孔隙度-滲透率儲(chǔ)層為特征，二者皆為非常規(guī)連續(xù)型石油聚集[11-17]。美國地質(zhì)調(diào)查局對(duì)Bakken頁巖可恢復(fù)資源潛力調(diào)研表明，Bakken組頁巖資源潛力約36.5億桶[18,19]，是北美頁巖油最具遠(yuǎn)景的頁巖層系。截至2015年，美國已經(jīng)在威利斯頓盆地Bakken組鉆遇約5 000口井[19]，取得了顯著的勘探開發(fā)成效。中國東部陸相頁巖分布面積廣、厚度大、有機(jī)質(zhì)熱演化處于生油高峰階段，渤海灣盆地沙河街組頁巖油資源潛力為(20.5～25.4)×108t[20,21]。截至2013 年底，濟(jì)陽拗陷300余口探井在沙河街組頁巖中見油氣顯示，其中30余口井獲工業(yè)油氣流[21]，預(yù)示著沙河街組有較大的頁巖油勘探前景，有必要對(duì)沙河街組頁巖儲(chǔ)層“甜點(diǎn)”特征展開研究(圖1)。

圖1　濟(jì)陽拗陷頁巖油鉆井分布圖Fig.1　Distribution of shale oil drilling wells in Jiyang depression

國內(nèi)學(xué)者對(duì)志留系龍馬溪組頁巖儲(chǔ)層研究后，認(rèn)為頁巖儲(chǔ)層形成機(jī)理主要為巖性、有利的礦物組合和有機(jī)質(zhì)熱裂解[22,23]；閆德宇等對(duì)海陸過渡相頁巖研究后，指出礦物巖石特征是頁巖儲(chǔ)層形成和保存條件之一[24]；大部分學(xué)者認(rèn)為頁巖儲(chǔ)層發(fā)育的主控因素為有利的沉積環(huán)境和有機(jī)地化特征[25-29]。但是，目前針對(duì)中國東部沙河街組頁巖儲(chǔ)層“甜點(diǎn)”特征和儲(chǔ)層形成機(jī)理尚未涉及。筆者在充分調(diào)研Bakken組頁巖儲(chǔ)層特征以及最新勘探開發(fā)的基礎(chǔ)上，依據(jù)分析測(cè)試數(shù)據(jù)、測(cè)井?dāng)?shù)據(jù)和巖性數(shù)據(jù)對(duì)中國東部濟(jì)陽拗陷古近系沙河街組頁巖儲(chǔ)層“甜點(diǎn)”特征進(jìn)行研究，通過對(duì)比Bakken組和沙河街組頁巖烴源巖分布、儲(chǔ)集巖性、儲(chǔ)集空間、儲(chǔ)層厚度、儲(chǔ)層物性、儲(chǔ)層分布和質(zhì)量，最終探討沙河街組和Bakken組頁巖儲(chǔ)層的形成機(jī)理。

1　液態(tài)烴比較

“甜點(diǎn)”是指鉆井的地層或深度層段最具有勘探潛力的頁巖遠(yuǎn)景區(qū)，表現(xiàn)為2種不同的方式：①識(shí)別盆地內(nèi)含油最好的地理區(qū)域；②識(shí)別完井段最好的地質(zhì)層段。許多研究者認(rèn)為頁巖儲(chǔ)層“甜點(diǎn)”是含油遠(yuǎn)景區(qū)或者是具有經(jīng)濟(jì)潛力的可生產(chǎn)區(qū)域，其目標(biāo)是綜合識(shí)別優(yōu)質(zhì)儲(chǔ)層特征(有機(jī)質(zhì)類型、有機(jī)碳含量、有機(jī)質(zhì)成熟度、儲(chǔ)層厚度、含油地質(zhì)儲(chǔ)量、孔隙度和滲透率)[8,30,31]。

沙河街組頁巖為陸相沉積背景，分布較穩(wěn)定，有機(jī)質(zhì)以Ⅰ型干酪根為主，總有機(jī)碳質(zhì)量分?jǐn)?shù)(wTOC)值范圍大，一般為0.41%～9.32%；有機(jī)質(zhì)熱演化程度較低，有機(jī)質(zhì)成熟度Ro值為0.45%～0.94%(表1)。Bakken組頁巖為海相沉積背景，分布穩(wěn)定，有機(jī)質(zhì)以Ⅰ型干酪根為主，wTOC值為5.36%～24.70%；有機(jī)質(zhì)熱演化程度低，Ro值為0.53%～1.30%，主要集中在0.51%～0.72%[5](表1)。

沙河街組頁巖儲(chǔ)層非均質(zhì)性極強(qiáng)，受陸源碎屑影響大，頁巖儲(chǔ)層孔隙度相對(duì)較低，測(cè)井孔隙度峰值集中在3%～7%，以發(fā)育微孔為主。Bakken組頁巖儲(chǔ)層非均質(zhì)性相對(duì)較弱，受陸源碎屑影響較小，頁巖孔隙度相對(duì)較高，測(cè)井孔隙度一般在5%～10%。

沙河街組頁巖主要分布在凹陷的眾多次級(jí)洼陷，頁巖厚度大，儲(chǔ)層厚度為13.60～90.00 m，分布范圍廣、面積大，含油飽和度為27.80%～122.40%，平均值為27.80%，可動(dòng)液態(tài)烴部分相對(duì)較低。Bakken組頁巖主要分布于背斜-穹窿帶，為陸棚濱岸沉積環(huán)境，頁巖厚度小，儲(chǔ)層厚度為3.10～12.20 m，含油飽和度為10%～71%，平均值為51%，可動(dòng)液態(tài)烴部分相對(duì)較高[13]。

沙河街組陸相頁巖地層經(jīng)歷了較強(qiáng)烈復(fù)雜的晚期構(gòu)造運(yùn)動(dòng)，影響頁巖的保存條件；超壓發(fā)育，壓力系數(shù)為1.21～1.81；凹陷地區(qū)地溫梯度較低，一般為0.20～0.45℃/km[32]；主力烴源巖層深度為2.8～5.1 km，液態(tài)烴多為中質(zhì)油。Bakken組海相頁巖構(gòu)造穩(wěn)定，保存條件好，超壓發(fā)育；地溫梯度較低，一般為0.25～0.34℃/km；主力烴源巖層深度為2.5～3.25 km，液態(tài)烴多為輕質(zhì)油[33]。

2　儲(chǔ)層特征對(duì)比

2.1Bakken組頁巖

Bakken組上段和下段富有機(jī)質(zhì)頁巖發(fā)育，廣 泛分布于整個(gè)盆地(圖2-A)。Bakken組中段發(fā)育粉砂質(zhì)白云巖，北部變薄，可容納空間增加導(dǎo)致厚度變化[13]。Bakken組中段發(fā)育的生物擾動(dòng)白云巖和砂質(zhì)白云巖為優(yōu)質(zhì)儲(chǔ)層巖性，是水平井主要目的層段(圖3-A)。Bakken組中段測(cè)井孔隙度(q)為1%～8%，滲透率(K)為(0.03～0.20)×10-3μm2(圖3-A)。Bakken組中段產(chǎn)油層深度為2 593～3 203 m，有效厚度>4.30 m。Bakken組儲(chǔ)集空間類型以粒間孔和晶間孔為主，儲(chǔ)層質(zhì)量向上改善，普遍發(fā)育超壓(圖2-A)[13]。

表1　沙河街組與Bakken組儲(chǔ)層特征對(duì)比Table 1　Comparison of reservoir characteristics of shale oil between Shahejie Formation and Bakken Formation

2.2沙河街組頁巖

目前針對(duì)濟(jì)陽拗陷東營(yíng)-沾化凹陷非常規(guī)油儲(chǔ)層研究仍然處于初級(jí)探索階段，而在東營(yíng)-沾化凹陷勘探井中古近系獲得工業(yè)油流，是近幾年中國東部非常規(guī)油氣勘探的突破之一。

濟(jì)陽拗陷古近系儲(chǔ)集層主要集中在沙三下亞段，巖性組合主要為深灰色灰質(zhì)泥巖、深灰色(灰褐色)灰質(zhì)油泥巖、灰色泥灰?guī)r、深灰色泥巖和灰色泥質(zhì)白云巖(圖2-B)。研究區(qū)牛52井沙河街組頁巖測(cè)井孔隙度為0.10%～8.60%，滲透率為(0.001～1.601)×10-3μm2(圖3-B)。沙河街組頁巖油儲(chǔ)集層空間以晶間孔、溶蝕孔和裂縫為主， 有機(jī)質(zhì)孔較少[17,34](表1)。一般地，沙河街組頁巖油井儲(chǔ)集層空間主要為泥巖裂縫型或是Ⅰ/Ⅱ/Ⅲ級(jí)頁巖裂縫型，儲(chǔ)層質(zhì)量向上改善(圖2-B)。與Bakken組頁巖儲(chǔ)層相比，研究區(qū)沙河街組儲(chǔ)層表現(xiàn)為巖性多樣，頁巖裂縫發(fā)育，且非均質(zhì)性較強(qiáng)(圖2-B)。

東營(yíng)-沾化凹陷5口頁巖油井沙河街組巖心物性統(tǒng)計(jì)結(jié)果表明：①有91%的樣品孔隙度>3%，孔隙度峰值為3%～7%;滲透率<5×10-3μm2的樣品占78%，其中有49%樣品滲透率<0.05×10-3μm2(圖4)。②埋藏較深，成巖作用強(qiáng)，發(fā)育部分次生孔隙。③含油飽和度高。④儲(chǔ)層非均質(zhì)性強(qiáng)，巖性多樣，粒度細(xì)，黏土礦物含量高，裂縫發(fā)育。⑤地層壓力高。其中：①孔隙度為0.10%～13.38%，平均值為4.33%，以低孔為主，少量中孔，無高孔特征(圖4-A)。②滲透率為(0.001～22.934)×10-3μm2，表現(xiàn)為低滲特征(圖4-B)。

圖2　頁巖油井測(cè)井特征圖Fig.2　Well logging characteristics for shale oil well(A) Bakken組頁巖[5]；(B)義186井沙河街組頁巖

圖3　頁巖油井孔隙度滲透率特征圖Fig.3　The characteristics of porosity and permeability for shale oil well(A)44-24 Vaira 井Bakken組中段[14]；(B)牛52井沙河街組頁巖

結(jié)合濟(jì)陽拗陷頁巖儲(chǔ)層特征，可將其分為2類：Ⅰ類儲(chǔ)集層，孔隙度為8%～12%，滲透率為(1.22～22.93)(10-3μm2，以油跡、熒光粉砂巖為主；Ⅱ類儲(chǔ)集層，孔隙度為3%～8%，滲透率為(0.01～1.59)×10-3μm2，以油斑泥灰?guī)r、灰質(zhì)泥巖、灰質(zhì)油泥巖和油頁巖為主。

圖4　沙河街組頁巖孔隙度與滲透率分布直方圖Fig.4　Histogram showing porosity and permeability for Shahejie Formation shale

沙河街組和Bakken組頁巖油產(chǎn)層對(duì)比，總體上共性大于個(gè)性(表1)。差異較大的幾點(diǎn)是總有機(jī)碳含量、儲(chǔ)集巖性、儲(chǔ)層厚度、儲(chǔ)層物性和儲(chǔ)層分布層段。

整體上，沙河街組頁巖wTOC為2.36%～9.32%，儲(chǔ)集巖性主要為泥灰?guī)r、泥質(zhì)白云巖、灰質(zhì)泥巖、灰質(zhì)油泥巖、泥巖和油頁巖，頁巖油儲(chǔ)集空間以粒間孔、晶間孔和裂縫為主。儲(chǔ)層厚度為13.60～90.00 m，儲(chǔ)集性能整體表現(xiàn)為低孔、低滲、高壓力、基質(zhì)滲透率極低、致密特征，以Ⅱ類儲(chǔ)層為主(表1)，儲(chǔ)層主要分布在沙三下亞段。

Bakken組wTOC為5.36%～24.70%，儲(chǔ)集巖性主要為生物擾動(dòng)白云巖和砂質(zhì)白云巖，儲(chǔ)集空間以粒間孔、晶間孔和裂縫為主。儲(chǔ)層厚度為3.10～12.20 m，儲(chǔ)集性能整體表現(xiàn)為低孔、低滲、普遍發(fā)育超壓、基質(zhì)滲透率極低、致密特征，以Ⅱ類儲(chǔ)層為主(表1)，儲(chǔ)層主要分布在Bakken組中段。

3　頁巖儲(chǔ)層形成機(jī)理對(duì)比

3.1有利的礦物組合

頁巖的礦物組成和有機(jī)質(zhì)熱演化是頁巖儲(chǔ)層發(fā)育的重要因素[1]。X射線衍射分析結(jié)果表明，沙河街組頁巖油產(chǎn)層主要礦物的質(zhì)量分?jǐn)?shù)分別為：石英平均為18.17%，長(zhǎng)石平均為1.40%，方解石平均為51.92%，白云石平均為6.17%，黃鐵礦平均為3.81%，另有少量的菱鐵礦(圖5-A)；黏土礦物平均為18.89%，以伊蒙混層和伊利石為主，未見蒙脫石(圖5-B)。Bakken組頁巖油產(chǎn)層主要礦物的質(zhì)量分?jǐn)?shù)分別為：石英為52%，長(zhǎng)石為9%，白云石為21%～70%(平均為38%)，黃鐵礦為9%，黏土礦物為17%[4]，上段和下段碳酸鹽平均值分別為10%和6%。脆性礦物含量控制頁巖的裂縫體積，黏土礦物含量影響頁巖的吸附能力[22]。研究區(qū)沙河街組石英含量不及Bakken組，方解石含量較高，黏土礦物含量相近;wTOC為0.71%～9.32%，平均值為3.10%(圖6)。因此，在沙河街組頁巖儲(chǔ)層中，溶蝕孔和黏土礦物晶間孔較發(fā)育，有機(jī)質(zhì)孔以發(fā)育微孔為主。

圖5　羅69井沙河街組頁巖礦物含量直方圖Fig.5　Histogram showing shale mineralogic and clay mineralogic content of the Shahejie Formation rocks in Well Luo-69(A)頁巖礦物含量直方圖；(B)黏土礦物含量直方圖

圖6　羅69井沙河街組頁巖儲(chǔ)層壓力綜合圖Fig.6　Comprehensive map showing shale reservoir pressure of Shahejie Formation in Well Luo-69

3.2有機(jī)質(zhì)熱演化

從研究區(qū)5口重點(diǎn)探井——義187井、義186井、義182井、牛52井和梁758井沙河街組巖石熱解地化參數(shù)和巖心統(tǒng)計(jì)結(jié)果來看，沙河街組頁巖絕大部分Ro值>0.76%，處于生油高峰階段。有機(jī)質(zhì)熱演化與轉(zhuǎn)換率(Rt)的關(guān)系研究表明(表2)，Ro值為0.76%時(shí)，沙河街組頁巖已經(jīng)發(fā)生排烴，牛52井深度為3 279.50～3 306.00 m、義187井深度為3 453.00～3 688.00 m的生烴潛力(S2×21.89)、含油量(S1×21.89)和排烴效率分別為(223.50×104t/km2, 295.52×104t/km2)，(25.83×104t/km2, 55.16×104t/km2)，(88%,81%)。Jarvie等對(duì)Barnett頁巖的研究認(rèn)為高的排烴效率，不僅為頁巖油的富集創(chuàng)造良好的生油條件，而且有利于改造頁巖儲(chǔ)層的孔隙度和滲透率[1]。

研究區(qū)沙河街組與Bakken組頁巖相比，差異最大的是有機(jī)質(zhì)轉(zhuǎn)換率。北部Dakota地質(zhì)研究表明，Bakken組頁巖Ro值為0.51%～0.72%，有機(jī)質(zhì)以Ⅰ型干酪根為主，有機(jī)質(zhì)裂解程度低，有機(jī)質(zhì)轉(zhuǎn)換率低于沙河街組[5]。沙河街組 頁巖同一深度段的游離烴S1值比S2值更小，這含油量=S1×21.89; 烴潛力=S2×21.89[1]。

表2　沙河街組頁巖有機(jī)質(zhì)轉(zhuǎn)換率Table 2　Organic matter transformation ratios for Shahejie Formation shale

代表處于低成熟度的有機(jī)質(zhì)轉(zhuǎn)換為油氣(圖6)。由此可見，有機(jī)質(zhì)轉(zhuǎn)換率能夠有效地預(yù)測(cè)沙河街組頁巖生油和排烴窗。

3.3普遍發(fā)育的超壓

超壓有利于頁巖油的富集和保存，高產(chǎn)頁巖油往往具有超壓[35]。根據(jù)鉆井資料對(duì)30口井沙河街組非常規(guī)頁巖儲(chǔ)層壓力的預(yù)測(cè)表明，沙河街組頁巖儲(chǔ)層普遍發(fā)育超壓。以沾化凹陷羅69井為例，計(jì)算的壓力系數(shù)為1.21～1.82，預(yù)測(cè)的壓力與實(shí)測(cè)地層壓力吻合較好(圖6)。羅69井沙河街組泥巖裂縫層段，孔隙流體壓力增加，這就解釋了為什么沙河街組頁巖普遍發(fā)育異常壓力縫，主要超壓成因機(jī)制為欠壓實(shí)和有機(jī)質(zhì)生烴增壓[34,36,37](圖6)。沙河街組頁巖Ro值為0.70%～0.93%，處在油氣的生成和保存期，這就使得生油巖熱解產(chǎn)生較大的S2值(圖6)。

H. L?seth等對(duì)富有機(jī)質(zhì)頁巖變形構(gòu)造研究表明油氣產(chǎn)量與異常壓力之間存在著相關(guān)關(guān)系[38]，一般地，超壓帶往往具有較高的含油飽和度，且超壓的頁巖油氣儲(chǔ)層需要識(shí)別“甜點(diǎn)”，而低壓儲(chǔ)層本身具有可生產(chǎn)性，不需要識(shí)別儲(chǔ)層“甜點(diǎn)”[39]。沙河街組頁巖與Bakken組頁巖儲(chǔ)層對(duì)比，二者均普遍發(fā)育超壓。

4　結(jié) 論

a. 對(duì)比研究區(qū)沙河街組與Bakken組頁巖儲(chǔ)層“甜點(diǎn)”特征，明確兩者存在共性與差異。沙河街組頁巖儲(chǔ)層“甜點(diǎn)”特征是有機(jī)質(zhì)以Ⅰ型干酪根為主，wTOC>2.36%，Ro為0.76%～0.90%，主要巖性為紋層狀泥灰?guī)r、泥質(zhì)白云巖、灰質(zhì)泥巖、油泥巖和油頁巖，孔隙度>3%，滲透率<0.5×10-3μm2，脆性礦物的質(zhì)量分?jǐn)?shù)>20%，含油飽和度為60%～90%，儲(chǔ)層厚度為13.60～90.00 m，儲(chǔ)層分布于沙三下亞段。說明研究區(qū)沙河街組具有高產(chǎn)油的地質(zhì)條件。

b. Bakken組頁巖儲(chǔ)層“甜點(diǎn)”特征是有機(jī)質(zhì)以Ⅰ型干酪根為主，wTOC>5.36%，Ro為0.54%～0.71%，砂質(zhì)白云巖，孔隙度>3%，滲透率<0.1×10-3μm2，脆性礦物的質(zhì)量分?jǐn)?shù)為50%，含油飽和度為50%～71%，儲(chǔ)層厚度為3.10～12.20 m，中段為優(yōu)質(zhì)儲(chǔ)層段。Bakken組頁巖是典型的連續(xù)型石油聚集。

c. 頁巖儲(chǔ)層的形成機(jī)理主要為有利的礦物組合、有機(jī)質(zhì)熱演化和普遍發(fā)育的超壓。沙河街組和Bakken組頁巖共同的儲(chǔ)層形成機(jī)理主要為有利的礦物組合和普遍發(fā)育的超壓。

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Comparison of “sweet spots” characteristics of shale oil reservoir rocks between Shahejie Formation in China and Bakken Formation in North America

CHEN Mei-ling, PAN Ren-fang, ZHANG Chao-mo, SHEN Lu-yin

KeyLaboratoryofExplorationTechnologiesforOilandGasResourcesofEducation,YangtzeUniversity,Wuhan430100,China

The characteristics and formation mechanism of the shale oil reservoir rocks in the Shahejie Formation and Bakken Formation shale are discussed. Geochemical analysis, lithology analysis, reservoir petrophysics analysis and mineralogical analysis show that the characteristics of sweet spots of shale oil features for the Shahejie Formation are as follows：①The organic matter is dominated by typeⅠ-kerogen; ②Total organic carbon is large than 2.36%, withRoranging from 0.76% to 0.90%; ③Reservoir is composed of laminated argillaceous limestone, argillaceous dolomite, limestone mudstone, oil mudstone and oil shale; ④The porosity is larger than 3% and permeability is less than 0.5×10-3μm2; ⑤Brittle minerals content is over 20%; ⑥Oil saturation is in the range of 60%～90%; ⑦shale thickness ranges from 13.60 m to 90.00 m; ⑧The reservoir rocks for the petroleum system are lower of the 3rd of Shahejie Formation. Similarly, the sweet spots of excellent reservoirs in Bakken are characterized by ①The organic matter is predominantly typeⅠ-kerogen; ②Total organic carbon>5.36%, withRoranging from 0.51% to 0.72%; ③Sandy dolostone has the best reservoir properties; ④Porosity >3% and permeability <0.1×10-3μm2; ⑤ Brittle minerals content>50%, ⑥ Oil saturation is in the range of 50%～71%; ⑦ Shale thickness ranges from 3.10 m to 12.20 m; ⑧ The middle member is excellent reservoir rocks. The formation mechanism of the Shahejie Formation and Bakken shale reservoirs includes favorable mineral composition and extensive development of overpressure.

Jiyang depression; Williston Basin; Shahejie Formation; Bakken Formation; shale oil; reservoir characteristics

10.3969/j.issn.1671-9727.2016.04.07

1671-9727(2016)04-0438-09

2016-04-30。

國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃(973)項(xiàng)目(2014CB239100)。

陳美玲(1986-)，女，博士研究生，研究方向：非常規(guī)油氣資源評(píng)價(jià), E-mail:chenmll@126.com。

TE132.2

A