Preparation Of Silica Fume Matrix Composite And Its Application In Oil Field Water Plugging

Tahe Oilfield is a carbonate reservoir located in Tarim Basin,Xinjiang.The geological structure conditions of its formation are very complex,with high temperature,deep burial,high salinity,strong heterogeneity characteristics.With the deepening of exploitation,most oil wells enter high water cut period after completion,and the production is low or even stopped,which has a serious impact on site construction.In view of the above problems,this project uses silica fume and biomass as raw materials to develop a low cost and environmentally friendly plugging agent system that meets the formation requirements,and its various properties were investigated one by one.Firstly,functionalized micro-nano hexadecytrimethoxysilane(HDTMS)/TiO₂/silica fume were prepared by sol-gel method and surface chemical modification.The optimal preparation conditions were determined as follows:the mass fraction of the modifier HDTMS was 15%,V_water:V_{anhydrous ethanol}=1:1,hydrophobic modification time of 120min.The composite particles were characterized by FT-IR,SEM,laser particle size analyzer,TG-DTG and XRD.It was found that TiO₂ was attached to the surface of the modified silica fume,and the particle surface changed from hydrophilic to superhydrophobic,and the contact Angle reached 155.8°.Through the laboratory core plugging test,the plugging efficiency of composite particles is more than 90%.It is proved that HDTMS/TiO₂/silica fume has a good function of adjusting the flow channel.Secondly,the characteristic fruit shell waste in Xinjiang was investigated.The shell of desert fruit with the highest lignin content was liquefied to prepare biomass-based phenolic resin crosslinking agent.The optimal preparation conditions were determined as follows:m(phenol):m(desert fruit shell)=3:1(mass ratio),The mass fraction of concentrated sulfuric acid was 12%,temperature is 130?,reaction time is90 min.The validity period of biomass based phenolic resin was 42 d at 25?.Then,a new type of organic-inorganic compound water-based gel was prepared by using biomass-based phenolic resin,polyacrylamide and surface modified silica fume as raw materials and used for deep water control in Tahe oilfield.The forming strength and temperature of the gel and its salt resistance and plugging performance were systematically evaluated.The results showed that when the amount of modified silica fume,polyacrylamide and biomass-based phenolic resin cross-linking agent is 0.5%,0.4%and 8%,respectively,the elastic modulus is above 40 Pa,which indicates that the gelatinization is strong.Silica fume can improve the thermal stability of gel by enhancing the strength of three-dimensional network structure.After aging for 15 d in the simulated Tahe reservoir environment,its elastic modulus remains at 10.08 Pa.In addition,the sealing rate of gel is 99.79%measured by chemical oil production evaluation instrument,which can meet the demand of oil field injection and water control,and is an ideal profile control material.Finally,in view of the problem that the gel solution is easy to be diluted by water when it enters the reservoir,the silica fume salt sensitive temporary plugging agent is developed.In order to protect the gelatinization of the gelatinized liquid,the gelatinized liquid is entered into the formation in advance by piecewise injection.The effect of shear rate on viscosity of base liquid at different concentration and temperature is investigated.It is found that the temporary plugging agent has good rheological properties.After curing,the elastic modulus of the temporary plugging agent is between870 MPa and 10520 MPa.In the reservoir environment at 130? aging can be natural degradation.It provides an effective guarantee for gelatinous gel to improve the deep oil and water flow state.Realized the temporary plugging agent and gel compound water plugging efficiency.