大型低渗-致密气田井网加密提高采收率对策——以鄂尔多斯盆地苏里格气田为例

提高采收率是中国低渗-致密气田稳产期间面临的核心问题,确定合理的加密井网是提高储量动用程度的关键。通过明确苏里格气田有效储层规模尺度与4种空间组合类型,评价指出气田动静储量比仅为15.3%,储量动用程度低剩余储量规模大,划分出直井未动用、水平井遗留和井间剩余3种剩余储量类型。提出了井网加密是提高井间剩余储量动用程度的有效措施,构建了采收率、采收率增量、平均气井产量、加密井增产气量、产量干扰率等井网加密评价指标体系,确立了合理加密井网需满足的标准。结合地质模型、数值模拟、密井网试验数据验证等手段综合评价认为,合理加密井网应与有效储层组合类型相匹配、与气价及成本条件密切相关。在目前气价波动范围及经济技术条件下,苏里格气田采用4口/km²的加密井网是合理的。

Well pattern infilling strategy to enhance oil recovery of giant low-permeability tight gasfield: a case study of Sulige gasfield,Ordos Basin

Enhancing oil recovery is an essential issue during the stable production of low-permeability tight sandstone gasfields in China, and the reasonable infilled well pattern is determined as the key to improve reserve producing degree. The effective reservoir scale and four types of space assemblage are identified, and the assessment indicates that the ratio between dynamic and static geological reserves (RDS)is only 15.3% in Sulige gasfield. The reserve producing degree is very low, while the residual reserve scale is large, divided into vertical-well unemployed reserve, horizontal-well remaining reserve and inter-well residual reserve. It is proposed that well pattern infilling is an effective measure to improve inter-well residual reserve, and the evaluation index system is constructed including recovery ratio, recovery increment, average gas well production, increased gas production of infilled well and production interference ratio. Meanwhile, the standard for reasonable infilled well pattern is also determined. Through geologic model, numerical simulation, test data verification of dense well pattern and other means, it is comprehensively concluded that the reasonable infilled well pattern is matched with effective reservoir assemblage type and closely related to natural gas price and relevant cost. In current gas price fluctuation range and economic-technological conditions, the infilled well pattern of 4 wells/km² is reasonable.