Ӱ�촨�а˽dz����ĵ�����������������

川中八角场香四气藏属低渗低孔致密砂岩气藏，压裂酸化是气层改造的主要措施。室内实验和现场实践证明：在气层改造过程中存在着多种地层损害因素：①水敏损害；②水锁损害；③压裂液残渣损害；④酸敏损害。这些因素使气层改造效果不甚理想。在岩心流动试验的基础上，结合电镜扫描、能谱分析等测试分析手段，对气层改造损害因素进行了定性、定量分析，认为：水敏产生的原因与储层含有膨胀性水敏矿物伊／蒙混层有关，另外还与低渗、细孔微喉结构和粘土矿物产状有关；水锁损害与含水饱和度、储层毛管压力、液体表面张力和润湿角等因素有关；目前压裂液残渣对该气层基岩渗透率影响不是主要因素，而水锁损害占总损害的６３．３％～９０．７％。在气层改造过程中，合理使用粘土稳定剂、铁离子稳定剂和助排剂等，对降低水敏、酸敏损害，帮助液体返排有重要作用。高能气体压裂是这类气藏改造的又一有效的工艺措施。

DAMAGE FACTORS AFFECTING XIANG 4 LOW PERMEABILITY GAS RESERVOIR STIMULATION IN BAJIAOCHANG FIELD IN MIDDLE SICHUAN

??The Xiang-4 gas reservoir in Bajiaochang field in Middle Sichuan is a tight sandstone gas reservoir with low porosity,low permeability and high gas saturation,and the acid fracturing is the major measure of gas reservoir stimulation.Through indoor experiment and field practice,it is proved that there are varied formation damage factors in the process of gas reservoir stimulation,i.e.??water sensitivity damage;??water lock damage;??fracturing fluid residue damage; ?? acid-sensitivity damage,which make the effect of gas reservoir stimulation non-ideal.Based on core flowing experiment and in combination with the means as electron microscope scanning and spectral analysis,the qualitative and quantitative analysis were carried out for the damage factors affecting gas reservoir stimulation.It is thought that the water sensitivity is caused by the expansive water sensitive minerals,the illite/smectite mixed layer,contained in reservoir,and also by the structure of the low permeability,fine pore and micro throat,as well as by the occurence of clay minerals;that the water lock damage is related to the factors as the water saturation,capillary pressure of reservoir,liquid surface tension and wetting angle,etc.;and that the fracturing fluid residue is not the major factor affecting on reservoir matrix permeability at present,while the water lock damage may account for 63.3%??90.7% of the total damage.In the process of gas reservoir stimulation,it is important for reducing water sensitivity damage and acid-sensitivity damage,and making liquid returning to reasonablly use clay stabilizing agent,ferric ion stabilizing agent and cleanup additive,etc.High energy gas fracturing is also an effective technological means of stimulation for such a gas reservoir.