Combining Preformed Particle Gel And Resin-coated Particle For Water Plugging In Fractures

During the development process of the high temperature and high pressure fractured Y reservoir in Tahe,high salinity water will flow into the production well along the large fracture.Therefore,water-plugging in fractures is a00 urgent problem needed to solve.Preformed particle gel(PPG)are widely used for profile control in fracture formations with high-temperature and high-salt.However,PPGs are easy to be washed out the production wells when they are used for water-plugging in fractures.In this thesis,it is proposed that the PPGs combine with Curable Resin-coated Particles(CRPs)to improve the retention capacity of the PPGs by curing the CRPs and effectively control the water production in reservoir.So,the researches are as follow:(1)PPGs were evaluated by the indexes of swelling,temperature resistance,salt tolerance,thermal stability and salt stability in this thesis.Finally,NPLS particles can maintain a swell of about 5.9 and long-term thermal stability at 120?,20 × 104 mg/L and a pH of 4.0-6.0.CRPs were evaluated by the indexes of cost,strength,density and curability,and granules could be cured under the reservoir temperature and salinity.The curing effect will be enhanced with the increasing dosage of curing agent,and weakened with increasing water content(2)The results show that the CRPs can improve the breakthrough and retention of the PPG as well as the plugging efficiency.With increasing size and concentration of the CRPs,the PPG breakthrough pressure gradient increases,the fracture permeability decreases.When the ratio of average calcite particle diameter to fracture width(RC)is small(0.15),the fracture permeability is difficult to be further reduced by increasing PPG concentration or PPG size.However,when the Rc increases to 0.21,the plugging performance in fractures filled with more CRPs or PPGs is better than that filled with larger CRPs.(3)The high temperature tubular model was constructed to study the plugging effect of PPGs and CRPs in vertical and oblique fractures.The results showed the cured CRPs can generate immobile packs in fractures and dramatically mitigate the PPG washout.When the average particle size of the PPGs is 1.20 mm,the breakthrough of PPGs will not occur.The small size of CRPs or the small ratio of CRP size to fracture size dedicated the low permeability and the homogeneity to CRP packs.While the less permeable and more homogeneous CRP packs,as well as the larger size PPG,contributed to the higher PPGs breakthrough pressure gradient.Moreover,some of the PPGs blocked in CRP packs could be released through high-speed brine injection from producers,which rendered the water plugging of the combined system recovery.(4)In order to further study the plugging performance of the combined particles system in heterogeneous fracture formations,a model of two-fractured-cores was designed.I found that The expanded PPGs will enter the wide fracture preferentially because of its small resistance,and plugged large fracture.And the narrow fracture becomes the main liquid production channel when combined particles system are injected into fractured models,and its percentage of liquid production is higher than 90%.The study of combining PPGs and CRPs for water plugging in fractures shows that it can cut off water well in the reservoir.This study provides new insight into the PPG treatment and will contribute to the water control in high temperature and high pressure fractured reservoirs.