塔里木盆地志留系-泥盆系层序地层及有利储层分布

应用地震、钻井、测井、野外露头等资料,在塔里木盆地志留系-泥盆系识别出了10个三级层序(Sq1~Sq10)及4个二级层序,其中Sq1、Sq4、Sq8和Sq10层序为Ⅰ型层序,其余为Ⅱ型层序.盆内Ⅰ型层序主要以滨岸-内陆棚沉积体系为特征,与典型的Ⅰ型层序相比,低位体系域缺失盆底扇、斜坡进积复合体等沉积体系;Ⅱ型层序主要以滨岸(潮坪)-陆棚沉积体系为特征.在志留纪早期,层序覆盖于起伏不平的剥蚀面之上,以填平补齐的充填沉积为主,中后期层序则发育在宽阔平坦的盆地内;在志留纪末-泥盆纪,盆地处于挤压状态,出现了大范围的隆起;在泥盆纪末期至早石炭世早期,又出现了一次新的海水侵入,发育了分布广泛的东河砂岩.这种层序格架明显不同于被动大陆边缘经典型的层序格架,它反映了稳定地块内坳陷性盆地的层序特点.Sq1、Sq4和Sq10层序的低位体系域是塔里木盆地志留系-泥盆系的3个有利勘探层位.

Silurian-Devonian sequence stratigraphy and favorable reservoir distribution in Tarim Basin

The seismic, drilling, well logging and outcrop data were used to recognize sequence stratigraphy of SilurianDevonian systems Ten tertiary sequences and four secondary sequences were divided. The tertiary sequences of Sq1，Sq4，Sq8 and Sq10 belong to the typeⅠ sequence, while the others are the typeⅡ sequence. The typeⅠ sequence in the basin was characterized by the seashoreinter shelf deposition system. Comparison with the classical typeⅠ sequence, the lowstand system tract (LST) of the typeⅠ sequence in this basin was lack of the deposition systems such as basin floor fans and slope transgress complex system. The typeⅡ sequence was characterized by the main deposited systems such as the coastal （tidal flat） and shelf deposition. The sequences formed in the Early Silurian were generated on the uneven erosion surface. The main deposition filled the surface. During the Middle and Late Silurian, the sequences formed in the broad and even basin. During the end of the Silurian Devonian period, the basin was in extrusion state and turned up a largescale uplift. During the end of the Devonian and the early Carboniferous, sea water was invaded again, a new transgress overlap was turned up, and a set of Donghe sandstone was widespread. This kind of sequence framework is different from the classical one that derived from the passive continental margin and reflects the sequence characteristics of the depression basin in the stable platform. The lowstand system tracts of Sq1, Sq4 and Sq10 are the favorable exploratory sequences in the SilurianDevonian systems of Tarim Basin.