江苏黄珏油田戴南组储层结构及合理注采井距

RESERVOIR TEXTURE AND RATIONAL WELL SPACING OF THE DAINAN FORMATION,THE HUANGJUE OIL FIELD, JIANGSU PROVINCE, CHINA

通过对黄珏油田戴南组的孢粉组合、地球化学特征、岩石学特征和测井相等分析,认为戴南组是在亚热带温暖潮湿气候条件下的滨岸—滨浅湖环境中发育的三角洲沉积;戴南组早期受南部的物源影响,戴南组后期的主导物源为北西方向;砂体类型有分流河道、河口坝、席状砂体、溢岸砂体,但分流河道砂体是主要的有效储集体;戴南组的分流河道为曲流河,其河道砂体平均宽度:戴二段的为329m,戴一段的为207m;砂体呈孤立状、透镜状,其间被分流间湾的泥质沉积物分隔,是典型的迷宫式储层结构。油砂体沿分流河道砂体分布,且规模较小。计算表明,选择注采井距为100～300m,才能大幅度地改善开发效果。

Production in the Huangjue oil field of the Subai basin, China, commenced in 1980.The field structure is a west-east trending rollover anticline. To date, only 8.7% of STOIIP(stock tank oil initially in place) has been recovered from the Eogene Dainan Formation divided into Daiyi Member and Daier Member. Such low recoveries are due to the complex reservoir textures and to early development practices. Reservoir management studies on optimizing recovery and identifying unswept oil volume are ongoing so as to maximize the venture's profitability.The reservoirs of the Dainan Formation consist of the distributary channel, mouth-bar, overbank and sheet sand deposits of the shallow lacustrine delta deposited in the flat shore-shallow lake under the warm, wet semi-tropical climate; however, pay zones are composed of predominantly distributary channel sandbodies. The ancient streams of the Dainan Formation, as a meandering river, flowed from south to north in the early Dainan period and came from dominantly the northwestern source area. The average widths of channel sandbodies in the Daier Member and Daiyi Member are 329 m and 207 m respectively. The reservoir texture in the Dainan Formation is a labyrinth described by Weber. This texture shows the channel sandbodies are isolated and lenticular. Hence,the internal communication within these pay zones is believed to be extremely bad. In addition, this texture also determines the sizes and distributions of oil sandbodies in the Dainan Formation.This work confirms and quantifies the impact of well spacing on the recovery factor, and figures the rational well spacing of the Huangjue oil field. To acquire an optimal improvement in the recovery factor, the rational well spacing ranges from 100 m to 300 m.