致密储层干化主剂筛选评价与配方研制

Selection, Evaluation,and Formulation of Drying Agents for Tight Sand Reservoirs

致密砂岩气藏储层一般具有较高的原始含水饱和度,测试显示干岩芯的渗透率是原始含水岩芯的10倍以上;除此之外,各种水基工作液均会接触储层进而侵入地层,形成液相滞留,增加近井地带或裂缝面附近的基质含水饱和度,进一步降低储层气相渗透率,大幅度降低产能。基于这一基本现象,研制了一种储层干化剂主剂ACHM,通过注入干化剂消耗地层水的原理性实验来评价地层水的消耗程度,并利用色谱及XRD衍射分析了反应后生产气及残渣组成。实验结果显示,该ACHM具有一定延迟反应时间、延迟反应时间与温度呈反向关系,且干化主剂的耗水量不受地层水类型及矿化度的直接影响,两种干化主剂的最佳混合摩尔比为0.25。

Tight sand gas reservoirs generally have relatively high levels of water saturation in their original state, and tests have shown that the permeability of dry cores is more than 10 times higher than that of the original water-containing cores. In addition, various water-based working fluids will seep into a formation upon contact with the reservoir, which leads to liquid phase retention. This increases the water saturation of matrices near the well or fracture plane, thereby further decreasing the gas phase permeability of the reservoir and greatly reducing its productivity. To solve this problem, we developed a reservoir drying agent called "ACHM". We first experimentally evaluated drying agents by measuring the depletion of formation waters after injecting the drying agents. Chromatography and X-ray diffraction(XRD) methods were also used to analyze the gases produced by the reactions between the drying agent and water, and the composition of their residues. The experimental results indicate that ACHM has a delay in its reaction time that is inversely proportional to the temperature. The water consumption of the drying agent is not affected by the type and salinity of the formation waters, and the optimal molar mixing ratio of the two drying agents was 0.25.