东濮凹陷北部盐间泥岩裂缝储层预测技术研究

Practical technology of inter-salt mudstone fracture prediction in the north of Dongpu depression

东濮凹陷北部盐间泥岩裂缝储层预测目前尚无适用技术.在分析泥岩裂缝储层地质与地球物理特征的基础上,发现盐间泥岩裂缝发育段由于富含脆性矿物,易受构造形变作用形成构造裂缝,且具有低速、低波阻抗、低泊松比及高电阻率等地球物理特征.据此,形成了剩余构造分析和广义多属性聚类分析为核心的2项适用于盐间超压、构造成因泥岩裂缝预测技术.其中,剩余构造分析技术将常规地质构造分解为构造背景、局部构造形变和随机因素3部分,突出局部构造形变产生的微曲率变化,从而达到预测泥岩裂缝的目的;广义多属性聚类分析则是将地震反演法与地震属性法结合起来进行属性优选,进行神经网络聚类分析,定性预测出泥岩裂缝发育区.实际应用中2套方法预测结果吻合度较高,依据预测结果部署的濮深18-1井在沙三段上亚段10砂组3 258 m处见到良好油气显示,产油量为215 ～ 420 m3/d.

There are no suitable technologies for the prediction of intra-salt mudstone fracture in the northern Dongpu depression.Based on the analysis of geology and geophysical characteristics of fractured mudstone reservoirs in the sag, it is concluded that the mudstone formations are easy to form tectonic fractures under tectonic deformation and with high content of brittle minerals. The geophysical characteristics of the fractured reservoirs are low-speed, low-impedance, low Poisson′s ratio and high resistivity etc. Accordingly, we proposed 2 fracture prediction technologies which are suitable for mudstone fractures of inter-salinastone overpressure and tectonic origin. The core technologies are based on residual structure analysis and generalized multi-attribute cluster analysis. The residual structural analysis technique considers conventional geological structure as three parts, namely, structure background, local tectonic deformation and random factor, and it highlights the changes of micro-curvature caused by local tectonic deformation which can be used in mudstone fracture prediction; the generalized multi-attribute clustering analysis technique combines seismic inversion method and seismic attribute to achieve attributes optimization, and it uses neural network clustering analysis to predict the fracture zone in mudstone qualitatively. According to the practical application results, this 2 method had a good agreement. Based on the fracture prediction results, Pu-Shen 18-1 well in the Zhongyuan oilfield was drilled and has obtained a good oil and gas show in 10 sand group of Es3 at a depth of 3 258 m, and the daily oil production can reach 215-420 m3.