For Victory Chengdao Oilfield Unconsolidated Sand Reservoir Into The Well Fluid System Applications

The chemical of the oil-field is used to resolve the chemical problem of the oil-field drilling,completion, oil rescovery,water fooding, the oil rescovery increasing and oil transportation.With the development of the oil industry at home and abroad, the chemical of the oil-field is promoted. On another hand, by the variety increasing,the quantity raising and the development of the chemical of the oil-field,the oil industry is pushed forword,the level of oil exploration is increased and the economic benefit is raised.At present,the oil trade and the chemical engineering trade in the world are collectively payed more attention to the research and the manufacture of the chemical of the oil-field.The reservoir of Chengdao offshore oil-field in Shengli is GUANTAO formation fluvial sand boodies,it is a heavy crude high saturation and high infiltration oil-bearing area of structural layered pool and lithologic oil reservoir,and the exploration of GUANTAO formation oil reservoir is given the first place. Upper part of Guantao Formation in Chengdao oil field is a fluvial sandstone with abundant oil and gas. It accounts for 76% of the proven OOIP of this formation. It is the main formation for extraction. It is recognized that this sandstone reservoir is of meandering river facies with positive rhythm , fine grained sediments mainly ; and has the characteristics of high porosity , high permeability , high oil saturation , high oil viscosity , and strong heterogeneity. The sand bodies change rapidly, and the sandstone is very loose and will have sand up inflow easily during oil production. The content of this high permeability unconsolidated sandstone reservoirs is low,and the Clay minerals content of reservoir is 10.7%. This reservoir is a typical fluvial facies deposit , loosly consolidated , with a low mineral and textural maturity , a strong heterogeneity. To the reservoir strata ,working fluids will cause stronge water sensibility,that would damage to the oil reservoir during the downhole operation. The averaging viscosity of crude of a part of productive intervals is 421mPa.s,this viscosity is high and the sand production is seriously. The maximum of pore radius of oil layers is 40.5μm and the average value is 7.7μm. At this satuation the pore is easily blocked up by the solid phase grain and milky fluid.And the block is difficultly to relieve once it is brought out. The fluid lossing could increase the water saturation of oil layers and debase the oil relative permeability.By the situation of the geologic strata,it is need urgently to develop a kind of drilling and completion fluid to meet to the exploration of the oil-field. a good deal of the experiment research shows that to the reservoir strata of the GUANTAO formation, working fluids will cause stronge water sensibility owing to I/S , rate sensibility at some extent owing to K, and weak acid sensibility owing to Ch.The critical TSD ranges form 2000mg/l to 4000mg/l.Then a variety of oil-field chemical doses are pulsated to meet to different layers homologously.By a great deal of field simulating experiment the optimized sand control dose and oil demulsifier are selected.There are three present estimation methods of oil-gas layer lesion .They are well testing analysis method,logging nalysis method and production dynamic nalysis method.At present the international generally accepted method is the well testing analysis method,It is the only method that can estimate theextent of damage of the geologic strata quantitively.All kinds of downhole operation would influence the geologic strata because of the use of drilling fluid.The well testing is proceeded after operation to collect the parameters.It can judge the good or bad of the drilling fluid by the extent of damage of the oil layers through the parameters.By selecting the representative oil well to performance the present application effect througeh well testing analysis,it is judged the optimized formulation and its protectctive efficacy.Though a variety of indoor experiment and present application,a new drilling fluid suiting to the geologic strata of CHENGDAO oil-field is developed,it has good sand control function,it can debase the inflation and sand production of the geologic strata and protect the oil layers.Because this drilling fluid is based on the filter brine, above 90% raw material can use local materials,this would save the stuff charge greatly,debase the operation cost,have a quite good economy benefit and generate a fairly good value.