高温深井复杂岩性气藏压裂技术

冀东油田五号构造沙河街组属于复杂岩性气藏，岩性主要以玄武岩、火山碎屑岩为主，埋深4781.6~5200 m，储层温度170~180℃，物性差（0.04~0.4 mD），前期采用φ139.7 mm套管压裂，排量2 m3/min时，压力70 MPa，停泵压力61 MPa，导致施工失败。通过对该气田火山岩岩心全岩、X射线衍射分析、酸溶、地应力及天然裂缝识别实验，认为天然裂缝发育且裂缝充填物多为酸溶矿物，提出了前置酸压+压裂改造工艺。从耐170℃高温有机硼低残渣瓜胶压裂液、稠化酸、优化射孔方式，提高地面设备承压、自降解降滤失剂封堵天然裂缝等综合处理措施出发，实现了适合南堡五号构造裂缝性火山岩深井压裂的顺利实施，并对前期失败井再施工，排量为5 m3/min时，最高压力为74 MPa，共加砂60 m3，顺利完成了施工。该技术在该区块现场实施3口井，单井最高加砂量125 m3，最高套压85 MPa，NP5-A井压后φ6.35 mm油嘴放喷，日产气量为10.7×104 m3。 

Technology of Fracturing Complex Lithologic Gas Reservoirs in High Temperature Deep Wells

The Shahejie Formation of the No.5 structure in Jidong Oilfield is a complex lithologic gas reservoir, the lithology of which is mainly basalt and volcaniclastic rocks. The reservoir, which has poor physical properties (porosity in a range of 0.04-0.4 mD) is buried in depths between 4,781.6 m and 5,200 m, with formation temperature between 170℃ and 180℃. The reservoir has previously undergone fracturing operation in the φ139.7 mm casing, with flowrate of 2 m3/min and pressure of 70 MPa. The pressure after stopping pumping was 61 MPa, and the operation was failed. From laboratory experiments (total analysis, Xray diffraction analysis, acid dissolution, ground stress and natural fracture identification) it was determined that natural fracture is developed in the reservoir and the fillings of the fractures are mainly acid-soluble minerals. Based on these analyses a technique of using pre-pad acid fracturing followed by fracturing operation was presented to improve the production of the reservoir. Using a high temperature organoboron low residue guar gum fracturing fluid (functioning at temperature up to 170℃), a thickened acid, combined with other measures such as optimized perforation method, increased compressive strengths of the surface equipment and plugging natural fractures with selfdegrading filter loss reducing materials etc., the fracturing operation was successfully performed in deep wells penetrating the fractured volcanic rock reservoirs in the No. 5 structures in Nanpu area. The well with failed fracturing operation previously was fractured again with flowrate of 5 m3/min and the maximum pressure of 74 MPa. Total amount of sand added was 60 m3, and the fracturing operation was successfully performed. The technology described above was used on 3 wells in Nanpu area.The maximum amount of sand added in a single well was 125 m3, and the maximum casing pressure was 85 MPa. The well NP5-A, after fracturing operation, was flowing with a φ6.35 mm choke, and the daily gas production output was 10.7×104 m3.