Preparation Of High Performance Shape Memory Epoxy Composites And Their Application In Leak Plugging

Leakage is a dangerous accident that often occurs during drilling and poses a serious risk to life and property.Plugging agents have been widely used as a reliable solution for containing well leaks.However,conventional approaches typically rely on inert materials such as sawdust,mica flakes and fibers,as well as gels and cements,which often do not match the size of the leakage channel and lack adequate compressive strength,leading to recurring leakage problems.Shape memory polymer materials have several advantages including rapid response,high deformability,and easy processing.These materials can be activated by subsurface temperatures and can be utilized to seal cracks in an adaptive manner,which has garnered considerable attention from researchers.Nevertheless,the shape memory polymer materials that are presently employed for leak plugging applications face issues with insufficient heat resistance and pressure-bearing capacity.At present,the real-life scenario of the leaky layer places higher demands on the plugging material.It is essential to develop a high temperature,high strength,high tenacity shape memory polymer plugging material that achieves adaptive bridging and efficient pressure-bearing plugging.Based on the properties of epoxy shape memory materials,this thesis proposes a method of utilizing epoxy resins in conjunction with various curing agents to produce shape memory epoxy resins(ESMP)and composite foam materials(ESMF)that possess high temperature resistance,strength,and toughness.These materials can be used for leak sealing purposes.In addition,as oil and gas exploration continues to expand into deeper and hotter formations,it is critical to protect reservoirs through the development of plugging materials with high temperature resistance,high pressure resistance,and degradability.These materials should be able to plug formations at elevated temperatures and also gradually degrade over time to achieve self-unplugging.Currently,there is no plugging agent that meets these challenging requirements;therefore,it is highly essential to research and formulate a high performance epoxy resin composite temporary plugging agent.This thesis considers the thermal and mechanical properties and degradability of epoxy resins and proposes the use of epoxy monomers and disulfide-containing curing agents to prepare dynamic cross-linked shape memory epoxy resins and composites to explore their degradability for use in plugging and unplugging of high temperature formations.The thesis focuses on the following:I: Preparation and application of high strength,high toughness shape memory epoxy resin:1.Preparation and properties of high-strength,high-toughness shape-memory epoxy resins:High strength and high toughness shape memory epoxy resin(ESMP)with adjustable glass transition temperature(Tg)and controllable shape memory performance was prepared by using the reaction of epoxy resin E51 and castor oil glycidyl ether(COGE)with curing agents4,4’-methylenedianiline(DDM)and polyetheramine-230(D230),and the effects of curing agent dosage and epoxy monomer type on the thermal properties,shape memory performance and mechanical properties of ESMP were investigated.The ESMPs with high temperature resistance,Tg in the range of 87.5～140 °C,shape fixation rate of 100%,shape recovery rate of95.5～100% and high strength were obtained.2.Preparation and performance study of high performance shape memory epoxy resin composite foam:Shape memory epoxy resin composite foam(ESMF)was prepared by adding polymeric swelling microspheres(MSH),and the effect of MSH dosage on the compression and recovery performance of ESMF was investigated,and ESMF with compression rates of 20～69.82% and recovery rates of 4.17～138% were obtained.3.Study on the application of shape memory epoxy resin material for leak plugging:The ESMF material was prepared by selecting an optimized formulation and conducting scaled-up tests,and was evaluated for simulated leak plugging.The ESMF material was effective in bridging and plugging narrow cracks with different openings at 100～120 °C with a pressure of 10 MPa and a leak volume of 30-55 m L.II.Preparation and properties of degradable shape memory epoxy resins and composites:1.Preparation of shape memory epoxy resins and composites with dynamic disulfide bonding cross-linking:Shape-memory epoxy resins and composites with dynamic disulfide bond cross-linking were prepared using epoxy monomer,disulfide-containing curing agent and polymer swelling microspheres(MSH).The effects of4,4’-dithiodianiline(DTDA)dosage,epoxy monomer type and MSH dosage on the thermal properties and shape memory properties of ESMP and ESMF were investigated,and Tg at 131.8～176.5 °C and 100% recovery rate of ESMP and ESMF were obtained.2.Study on the degradation properties of epoxy resin composite foam:The effects of the amount of disulfide-containing curing agent,the type of epoxy monomer,the amount of accelerator,the amount of MSH and the particle size on the degradation properties of the material were investigated,and the degradation mechanism and degradation kinetics were discussed.