琼东南盆地梅山组浊积扇储层主控因素及其有效性分析

Controlling factors on the effectiveness of turbidite fan reservoir of the Meishan Formation,Qiongdongnan Basin

琼东南盆地中新统梅山组浊积扇是该地区天然气最主要的贡献者之一,其沉积机理、储层主控因素分析及储层预测方法技术的提高直接影响着该区天然气增储上产。本文根据大量的岩心及井壁取心等实测资料,对该区钻井揭示的海底扇储层进行了系统分析。研究表明,琼东南盆地梅山组浊积扇类型及其内部组成、底流改造是影响和制约储层预测成功率的关键,其中断控陡坡根部盆底扇、深洼盆底扇和峡谷切割深洼盆底扇是储层相对发育的浊积扇类型,底流改造对处于敞流环境的中扇、外扇储层品质改善至关重要。对于深水环境的浊积扇储层而言,沉积因素,如岩性侧封、储层上倾尖灭构成这类岩性圈闭有效性的主要原因,对于峡谷切割型深洼盆底扇需要重点考虑岩性侧封,对于深洼盆底扇需要重点考虑上倾尖灭。研究成果可广泛应用于深水浊积扇储层预测。

The turbidite fan of Miocene Meishan Formation in Qiongdongnan Basin is one of the main contributors of natural gas in the area.To increase the natural gas reserve and production in this area,the sedimentary mechanism,the controlling factors and prediction methods were studied.According to a large number of DST,geological fluid sampling,core and rotary sidewall coring measured data,and relevant enterprise standards,the turbidite fan reservoir of the could be divided into four levels of grade:high-quality,good,effective,and tight.The four levels correspond to high production,commercial production capacity,merely productive capacity,and dry layer.Results show that the type of turbidite fans and its internal composition,bottom current reformation,and reservoir effectiveness are key factors on reservoir prediction success.Fault-terrace basin floor fans,basin floor fans cut by canyon,and integral basin floor fans are three types of relatively good reservoirs;and bottom current reworking is important to improve the reservoir of middle fan and outer fan in open flow environment.For the basin floor fan cut by canyon,the lithological side seal needs to be focused in the future.For the integral basin floor fans,the reservoir pinch out shall be considered too.At present,the rate of reservoir prediction of the Meishan turbidite fans in this area is very low.The methods developed in this study shall be of great value to improve the success rate of reservoir prediction.