Abstract:

Laboratory research on protective agents for reservoirs was carried out to solve the problem of reservoir damage during drilling in Biyang Sag of Henan Oilfield.Under alkaline conditions,starch microspheres were prepared with corn starch, epichlorohydrin, and polyethylene glycol 20000 as the main raw materials, and then the starch?based protective agent DYB for reservoirs was prepared by the compound of the starch microspheres, regenerated fiber, calcium carbonate (QS?2), and emulsified asphalt (SFT). Scanning electron microscope and thermogravimetric analyzer were used to study the micromorphology and thermal stability of the synthesized product and evaluate the performance of DYB, such as shale rolling recovery and plugging. The results indicate that the particle size of starch microspheres is in the range of 3~5 μm, and the shale recovery rate of DYB in the base slurry is over 85.0%, the API filtration loss of the base slurry after aging at 120~180 ℃ is controlled within 12 mL. After 3.0% DYB is added to the simulated field drilling fluid, its pressure?bearing capacity in the sand bed can reach 4.00 MPa, while the membrane pressure?bearing capacity in the artificial core is over 10.00 MPa, and the recovery value of core permeability is over 82.0%.

Key words: Reservoir protective agent, Starch microspheres, Shale rolling recovery rate, Sand bed plugging, Temporary plugging under pressure

摘要：

针对河南油田泌阳凹陷钻井过程中的储层损害问题，开展油层保护剂的室内研究。在碱性条件下，以玉米淀粉、环氧氯丙烷、聚乙二醇20000等为主要原料制备淀粉微球，再通过与再生纤维、碳酸钙（QS?2）、乳化沥青（SFT）复配制得淀粉基油层保护剂DYB。采用扫描电镜、热重分析仪研究合成产物的微观形貌和热稳定性，对油层保护剂DYB的页岩滚动回收和封堵等性能进行评价。结果表明，淀粉微球的粒径在3~5 μm，油层保护剂DYB在基浆中的页岩回收率达到85.0%以上，经120~180 ℃老化后基浆的API滤失量控制在12 mL以内。在模拟现场钻井液中加入质量分数3.0%的DYB后，其在砂床中的承压能力为4.00 MPa，在人造岩心中的膜承压能力在10.00 MPa以上，岩心渗透率恢复值在82.0%以上。

关键词: 储层保护剂, 淀粉微球, 页岩滚动回收率, 砂床封堵, 承压暂堵