东营凹陷滑塌浊积岩沉积特征及油气藏勘探技术

Depositional characteristics of fluxoturbidite and exploration technologies of subtle reservoirs in the Dongying sag

尹太举 张昌民 李中超

Yin Taiju Zhang Changmin Li Zhongchao

东营凹陷滑塌浊积岩是前缘席状砂或河口坝砂体在重力、地震等作用下,外部剪切力克服其内部的粘结力而发生崩塌、滑移后再沉积的产物,具有分异性好、结构和成份成熟度较低特征的粉、细砂岩。据浊积体的平面发育特征,可分为非沟道化的浊积岩和沟道化的浊积岩两种类型。基于滑塌浊积岩的成因,滑塌浊积岩发育地区不能采用常规的旋回对比法及高分辨率层序地层等对比技术,应采用井震结合确定大的地层界限及标志层逐级控制的对比方法。滑塌浊积岩储层以微孔隙组合为主,单层平均孔隙度一般小于23%,平均渗透率小于50×10μm,属中低孔低渗储层。浊积岩储层评价, 重点考虑砂体平面分布的连续性、连通性、砂体的厚度及含油性。滑塌浊积岩形成于深湖区,近油源,油源充足,油气垂向或侧向或沿断层短距离运移成藏,多为岩性和岩性-断层遮挡油气藏。滑塌浊积岩勘探主要是应用沉积微相分析和地震反演两项技术进行储层预测。依据储层预测结果,提供了11个可供滑塌浊积岩隐蔽油气藏的勘探目标。

Fluxoturbidite is the product of redeposition of frontal sheet sand or river mouth bar sandbodies, which avalanche and slide when the external shearing force triggered by gravity and earthquake overcome the internal cohesive force. It is characterized by siltstone and fine sandstone with good sorting and relatively high tex-tural and compositional maturities. According to the areal development characteristics of turbidite, it can be basically divided into two types, namely non-channelized and channelized turbidites. The conventional sedimentary cycle correlation and high resolution sequence stratigraphic correlation technologies are not applicable in fluxoturbidite areas, due to their unique genesis. Well data and seismic data should be integrated to recognize large stratigraphic boundaries and marker beds and realize strata correlation step by step. Fluxoturbidite reservoirs are dominated by micropores and are of moderate to low porosity and low permeability reservoirs; the average porosity of single layer is generally below 23%, and the average permeability is less than 50×10μm. Evaluation of fluxoturbidite reservoirs should be focused on the areal continuity, connectivity, thickness and oil-bearing properties of sandbodies. Fluxoturbidite reservoirs have been deposited in deep lake near the rich source rocks. Hydrocarbons would migrate vertically, laterally or along faults in short distance and accumulate in lithologic and lithologic-fault screened traps. Sedimentary microfacies analysis and seismic inversion are commonly used for reservoir prediction during exploration of fluxoturbidite reservoirs. Based on the results of reservoir prediction, 11 targets are presented for exploration of fluxoturbidite subtle reservoirs.

10.11743/ogg20060115