可降解储层暂堵剂合成及性能评价

Synthesis and Performance Evaluation of Degradable Reservoir Temporary Blocker

摘要: 针对目前暂堵剂存在对储层孔候尺度匹配度要求高、作用单一、环保性能差等问题，采用丙烯酰胺、抗盐单体、丙烯酸对淀粉改性，通过接枝反应并在交联作用下合成淀粉基吸水树脂，并引入纳米碳酸钙作为刚性内核，制备出了淀粉基可降解暂堵剂(STPA)。采用红外光谱、扫描电子显微镜及热重仪对STPA进行表征，并评价了STPA的吸水性能、封堵性、抗剪切性、抗温性、抗盐性、降解性及环保性能，揭示了STPA的作用机理。结果表明，提纯STPA分子结构包含羧酸基、酰胺基、甲基、S=O等官能团，证实了STDA合成的可行性；其表面具有孔洞和皱褶，且孔状结构分布较均匀，呈现许多深浅不一的沟壑和多层蜂窝状，均匀多孔，吸水性能良好；抗温125℃，抗盐5%，抗钙0.5%，降解率50%；有效封堵泥饼孔洞、使泥饼结构更致密，具有自适应性，对低渗透、中等渗透岩心在返排压力0.4 MPa、高渗透岩心0.6 MPa时，渗透率恢复值可达85%。研究成果将为油气层保护技术，特别是储层保护剂的研发及其机理认识方面提供借鉴。

Abstract: In view of the problems of temporary plugging agent, such as high requirement of reservoir pore scale matching, single action and poor environmental protection performance, a starch-based degradable temporary plugging agent (STPA) was prepared by synthesis of starch-based absorbent resin through grafting and crosslinking modified starch with acrylamide, salt resistant monomer, acrylic acid, and introduced nano-calcium carbonate as a rigid core. STPA was characterized by infrared spectroscopy, scanning electron microscopy and thermogravimetry, and evaluated its water absorption, plugging, shear resistance, temperature resistance, salt resistance, degradation and environmental protection, revealed the action mechanism of STPA. Results showed that the molecular structure STPA purification includes functional groups such as carboxylic acid group, amide group, methyl group and S=O group, confirming the feasibility of STDA synthesis; its surface has holes and folds. The pore structure is more uniform, in the form of many deep and shallow gullies and layers of honeycomb, with uniform porous and good water absorption. It has 125˚C and 5% salt resistance, 0.5% calcium resistance and 50% degradation. Moreover, it can seal mud cake hole effectively, make mud cake structure denser and adaptive. When the core of low permeability and medium permeability is 0.4 MPa, 0.6 MPa, the permeability recovery value can reach 85%. The research results will provide a reference for the research and development of reservoir protection technology, especially reservoir protection agent, and its mechanism understanding.