松辽盆地徐深气田火山岩气藏储量动用及开采特征

Available reserves from volcanic-rock reservoirs in Xushen gasfield of Songliao Basin and reservoir development characteristics

大庆徐深气田火山岩天然气储量占到已开发地质储量的90.8%,是气田最主要的供气保障。随着开发的深入,火山岩气藏在产能与动态储量特征认识面临新的问题,影响气田的长远发展。从储层特征着手,结合气藏开发实践,多方法综合运用,阐述了火山岩气藏井控动态储量特点、增储方向、采收率特征、气井渗流以及产能特征。结论认为:①火山岩储层基质致密,其间分布高、低孔渗的储渗结构天然裂缝发育,可通过压裂缝沟通周围的孔隙和天然裂缝,形成相对高渗的主流区,主流区周围是以致密基质为主的补给区;②开发后先动用主流区储量,再逐步动用补给区储量,井控动态储量逐步增加;③压裂改造以后,在主流区提高了气井的初期产能,但补给区是气井长期的物质保障,当补给区补给量增加到最大能力后,将逐步下降,改善补给区致密基质渗透性有提高产能和增加采收率作用。

In Xushen gasfield, PetroChina Daqing Oilfield Company, the gas reserves in volcanic rocks account for 90.8% of developed geological reserves. With field development, a long-term development is influenced by new problems occurred while investigating some characteristics of both production capacity and dynamic reserves. So, the features of well-control dynamic reserves, the trend of reserve increase, the characteristics of recovery factor, the well seepage, and the production capacity were expounded by using multiple methods and based on reservoir characteristics and development practice. Results show that (1) these volcanic-rock reservoirs are characterized by tight matrix, and reservoir-storage structures with high or low porosity and permeability, as well as developed natural fractures. However, pores may be connected with natural fractures through induced fractures to form the main flow area with relatively higher permeability. And around this area, tight matrix may serve as the main recharge area;(2) in the process of development, gas reserves in this flow area were produced firstly and then those in the recharge area were gained to gradually increase well-control dynamic reserves;and (3) after fracturing, an initial productivity was increased. However, the recharge area provides long-term material guarantee, and its recharging amount declines gradually after reaching the maximum, so raising the permeability of tight matrix in this recharge area is conducive to increasing production capacity and recovery factor.