歧口凹陷歧北斜坡白云岩演化规律研究
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摘要
在古近系沙河街组沙一段沉积期,为歧口凹陷最大湖扩期,在西南部整体古地理为宽缓的湖湾环境,气候潮湿温暖,物源供给较弱,在这种条件下,该地区发育大面积的碳酸盐岩沉积,以白云岩夹油页岩互层分布为特征。利用歧北斜坡两口重点井的岩心资料,对该区内的白云岩演化特征进行分析。研究表明,湖平面的升降决定了古地理环境,直接影响了白云岩发育的类型。歧北高斜坡区,水体较中斜坡浅,自下而上发育生屑灰岩、微晶云岩、灰质云岩、云质灰岩,表明古地理环境由粒屑滩—局限洼地—湖湾的演化过程;而在歧北中斜坡区,位于港西凸起周缘,早期主要为浅滩环境,发育灰质云岩和云质灰岩,向上过渡为微晶云岩、泥质云岩、泥岩,湖平面的多次升降,决定了该区古地理环境由浅滩—局限洼地—湖湾—半深湖的演化过程。通过地质钻探,该区在部分区域的白云岩已发现油层,证明该区白云岩储集层具有良好油气潜力,白云岩储集层已成为歧口凹陷古近系非常规油气增储的重要领域之一。
In the southwest of Qikou depression, the sedimentary period of Member 1 of Shahejie Fm. was corresponded with the expansion of lake basin, which belonged to the large ancient bay environment, with the warm and wet climate, and lacking of the source supply. In this environment, the carbonate rocks were deposited greatly, and dolostones interbedded with oil shales dominated especially. Based on the data of two wells on the Qibei slope, this paper analyzes the evolution characteristics of the dolostones. Research results show that the paleogeographic environment was controlled by the rise and fall of the lake level, and affected the type of dolostones. In the high position of the slope, the lake level was shallow, and the bioclast limestone-micritic dolostone-calcite dolostone-dolomitic limestone were developed from bottom to top. It shows that the palaeogeographic environment evolved from debris beach-local depression to lake bay. In the middle position of the slope, the calcite dolostone and dolomitic limestone were developed, up toward the rocks changed into the micritic dolostone and mudstone. Rising and falling of the lake level controlled the evolution trends of palaeogeographic environment——from shoal-confined depression-lake bay to semi-deep lake. By the drilling, some oil-bearing layers are found in the dolostone in local areas to the southwest Qikou depression. So dolostone reservoir has become one of the important layers of Paleogene petroleum in Qikou depression.
In the southwest of Qikou depression, the sedimentary period of Member 1 of Shahejie Fm. was corresponded with the expansion of lake basin, which belonged to the large ancient bay environment, with the warm and wet climate, and lacking of the source supply. In this environment, the carbonate rocks were deposited greatly, and dolostones interbedded with oil shales dominated especially. Based on the data of two wells on the Qibei slope, this paper analyzes the evolution characteristics of the dolostones. Research results show that the paleogeographic environment was controlled by the rise and fall of the lake level, and affected the type of dolostones. In the high position of the slope, the lake level was shallow, and the bioclast limestone-micritic dolostone-calcite dolostone-dolomitic limestone were developed from bottom to top. It shows that the palaeogeographic environment evolved from debris beach-local depression to lake bay. In the middle position of the slope, the calcite dolostone and dolomitic limestone were developed, up toward the rocks changed into the micritic dolostone and mudstone. Rising and falling of the lake level controlled the evolution trends of palaeogeographic environment——from shoal-confined depression-lake bay to semi-deep lake. By the drilling, some oil-bearing layers are found in the dolostone in local areas to the southwest Qikou depression. So dolostone reservoir has become one of the important layers of Paleogene petroleum in Qikou depression.
引文
蒲秀刚,周立宏,肖敦清,等,2011.黄骅坳陷歧口凹陷西南缘湖相碳酸盐岩地质特征[J].石油勘探与开发,38(2):163-168.
蒲秀刚,周立宏,韩文中,等,2014.歧口凹陷沙一下亚段斜坡区重力流沉积与致密油勘探[J].石油勘探与开发,41(2):119-121.
姜超,邓爱居,田小川,等,2014.歧口凹陷西南缘沙一段下部碳酸盐岩储层特征及控制因素[J].东北石油大学学报,37(1):385-387.
姜文亚,柳飒,2015.层序地层格架中优质烃源岩分布与控制因素——以歧口凹陷古近系为例[J].中国石油勘探,20(2):119-121.
李宏军,刘国全,石倩茹,等,2009.歧口凹陷西南缘岩性油气藏成藏条件、分布规律及典型实例剖析[J].天然气地球科学,20(4):1-3.
刘玉梅,刘艳芬,彭彬,等,2010.歧口凹陷西南缘沙一段湖相白云岩储层识别及储量参数计算[J].天然气地球科学,21(4):474-477.
王振升,周育文,刘艳芬,等,2012.歧口凹陷西南缘湖相碳酸盐岩油气聚集规律浅析[J].中国石油勘探,17(2):17-21,87.
杨剑萍,晋同杰,姜超,等,2015.歧口凹陷西南缘沙一下亚段碳酸盐岩沉积模式[J].新疆石油地质,36(2):119-121.
蒲秀刚,周立宏,韩文中,等,2014.歧口凹陷沙一下亚段斜坡区重力流沉积与致密油勘探[J].石油勘探与开发,41(2):119-121.
姜超,邓爱居,田小川,等,2014.歧口凹陷西南缘沙一段下部碳酸盐岩储层特征及控制因素[J].东北石油大学学报,37(1):385-387.
姜文亚,柳飒,2015.层序地层格架中优质烃源岩分布与控制因素——以歧口凹陷古近系为例[J].中国石油勘探,20(2):119-121.
李宏军,刘国全,石倩茹,等,2009.歧口凹陷西南缘岩性油气藏成藏条件、分布规律及典型实例剖析[J].天然气地球科学,20(4):1-3.
刘玉梅,刘艳芬,彭彬,等,2010.歧口凹陷西南缘沙一段湖相白云岩储层识别及储量参数计算[J].天然气地球科学,21(4):474-477.
王振升,周育文,刘艳芬,等,2012.歧口凹陷西南缘湖相碳酸盐岩油气聚集规律浅析[J].中国石油勘探,17(2):17-21,87.
杨剑萍,晋同杰,姜超,等,2015.歧口凹陷西南缘沙一下亚段碳酸盐岩沉积模式[J].新疆石油地质,36(2):119-121.
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