Abstract:

In the late development stage of heavy oil reservoirs by steam injection huff and puff，the vertical well + horizontal well pattern steam drive （VHSD） is considered an effective way to sustain the recovery of mature heavy oil blocks. However，due to the interlayer distribution，low formation pressure coefficient，and the presence of steam channels in mature heavy oil blocks，the resultant oil gain of this method is unsatisfactory. The SAGD dilatation stimulation technology for heavy oil recovery can effectively break through the interlayers between injection well and production well and improve the overall production degree of the reservoir. Therefore，it is necessary to perform in-depth investigation of the dilatation technology for heavy oil reservoirs in the context of the VHSD. A one-dimensional core dilatation experiment was carried out，and the results showed no considerable post-dilatation variation of the core porosity and yet，an increase in the effective permeability by about 200 times. Based on large scale three-dimensional physical modeling，a dilatation experiment under the VHSD well pattern mode was carried out. The experiment shows that：（1） When the horizontal well trajectory is parallel to the direction of the maximum principal stress，the dilatation area is larger；（2） The distance of less than 35m between the vertical well and horizontal well is conducive to the formation of the combined dilatation zone；（3） After the high-permeability channels are plugged，an effective dilatation zone can still be formed. The experimental results are applied to the field practice，which shows that the recovered degree of the horizontal section of the production horizontal well is increased by more than 15% and the well production is effectively improved. This research provides effective references for the optimization of key parameters of the dilatation stimulation of heavy oil reservoirs，and is of great significance for the continuous efficient development of mature heavy oil blocks.

Key words:

heavy oil reservoir, VHSD, follow-up development, physical modeling simulation, dilatation stimulation

摘要： 稠油油藏注蒸汽吞吐开发后期，采用直井+水平井组合井网驱泄模式（VHSD）是稠油老区接替开发的有效方式。
由于稠油老区普遍存在隔夹层展布、压力系数低、汽窜通道发育等问题，接替开发效果优势不明显。稠油SAGD扩容改造技
术能够有效突破注采井间隔夹层，提高储层整体动用程度，需要对稠油储层VHSD井网模式下扩容改造技术开展深入研究。
开展一维岩心扩容实验，结果显示扩容后岩心孔隙度变化不大，而有效渗透率扩大约200倍。开展VHSD井网模式下三维大
物模扩容改造实验，实验表明：（1）水平井轨迹平行于最大主应力方向时，扩容区规模越大；（2）直井-水平井距离<35 m有
利于复合扩容区的形成；（3）对高渗通道封堵后仍可形成有效的扩容区。将该研究成果应用到矿场实践，生产水平井水平
段动用程度提升15%以上，产量得到有效提高。该研究成果为稠油油藏扩容改造关键参数优化提供了有效依据，对稠油老
区持续高效开发具有重要意义。

关键词:

稠油油藏, VHSD, 接替开发, 物理模拟, 扩容改造