Research On Drilling Fluid For Medium And High Permeability Reservoir Protection In Dagang Zaoyuan Oilfield

Zaoyuan Oilfield belongs to one of the key regular energy blocks of Dagang Oilfield.The medium-high permeability reservoir is mainly located in the Zijiao and Fenghuadian blocks of Zaoyuan Oilfield.The basic physical properties of the reservoirs in the block are complex and sensitive mineral types and contents.It is rich,and thus it is easy to cause reservoir sensitivity and reservoir damage.The reservoir protection work of Zaoyuan Oilfield was carried out earlier,mainly guided by the shielded temporary plugging theory.The drilling fluid systems currently in use are mainly polymer drilling fluids and siliconbased anti-collapse drilling fluids.Experiments show that the current drilling fluids are stored.The layer protection performance is not good,especially the drilling fluid has poor effect on the reservoir sealing performance,which causes the drilling fluid filtrate to invade the reservoir and cause damage.The medium-high permeability reservoir in Zaoyuan Oilfield has moderately strong water sensitivity,alkali sensitivity and salt sensitivity damage.According to the characteristics of reservoir sensitivity damage in the medium-high permeability reservoir of Zaoyuan Oilfield,the reservoir protection performance of the current polymer drilling fluid and silicon-based anti-collapse drilling fluid is analyzed,and the current drilling fluid loss and pollution are measured.After the recovery rate of core permeability,the results show that the plugging performance of the current drilling fluid is not good,and the reservoir core permeability recovery value is low the recovery value of the permeability of the medium permeability reservoir is 72.50%,and the permeability recovery value of the high permeability reservoir is 72.56%,did not meet the reservoir protection performance requirements of drilling fluid.In view of the problem of reservoir damage caused by the insufficient sealing performance of the existing drilling fluid reservoir in Zaoyuan Oilfield,this paper proposes a fine calcium temporary blocking particle optimization scheme suitable for the medium-high permeability reservoir of Dagang Zaoyuan Oilfield based on the ideal filling theory.The composite rigid and flexible fiber powders were included,and the plugging reservoir protection agent FGX for drilling fluids was studied.The raw materials and wetting agents of the reservoir protection agent were optimized,and the experiments were verified and drilled.The compatibilityof the liquid is good.Then,through the reservoir damage experiment,the reservoir damage test and permeability recovery experiment of the fine calcium temporarily blocked particle formula and the plugged reservoir protectant FGX and the dril ing fluid based on the ideal fil ing theory were studied.The damage experiment showed that the fluid loss of the drilling fluid with the ideal filling of the calcium temporary blocking formula was also significantly reduced,the permeability of the medium permeability core reached 86.4%;and the filtration loss of the drilling fluid for the field well with the addition of the reservoir protection agent FGX Significantly reduced,core permeability recovery value reached 94.12%,high permeability core permeability recovery value reached 88.90% and 94.39%,respectively,indicating that FGX has good sealing performance,can play a significant reservoir protection effect,and thus improve oil and gas The production of the layer.