Study On Dynamic Production Law Of Fracturing Tracer Profile In Horizontal Wells

With the large～scale application of horizontal well fracturing in the development of low～grade oil and gas reservoirs,the fracturing tracer technology which can timely and quantitatively evaluate the staged fracturing effect and production performance is in the ascendant.The links such as agent selection,injection,sampling and analysis of fracturing tracer have been relatively mature,but the profile dynamic output analysis method based on fracturing tracer monitoring is not perfect,especially in the environment of large pressure fluctuation,huff and puff connection,multiphase seepage and the interaction between fracture and bedrock,the theoretical output law of tracer and formation fluid needs to be clarified first.Using the fine reservoir numerical simulation method,the horizontal well fracturing tracer simulation numerical model is established,the effects of reservoir parameters,fracturing parameters and fluid parameters on tracer dynamic production profile are mainly evaluated,the variation laws of underground pressure distribution,flow pattern,profile production,profile water cut,tracer concentration and tracer recovery are clarified,and the main control factors of horizontal well fracturing tracer profile dynamic production are summarized.Main conclusions and understandings:(1)Through numerical simulation,the influencing factors of mass transfer and diffusion of fracturing tracer under formation are clarified.The mass transfer and diffusion of tracer are mainly controlled by injection mode,formation parameters and physicochemical parameters.The output concentration curve of tracer shows a single peak,which is mainly affected by adsorption,diffusion and migration distance.The indexes such as peak production concentration and cumulative recovery rate of aqueous tracer are obviously better than those of gas tracer.At the initial stage of flowback,the water production rate decreases,the gas production rate increases,the tracer output concentration decreases and the recovery volume decreases.(2)The influence of tank parameters,fission parameters and fluid parameters on the dynamic production of tracer profile is explained.With the increase of formation permeability,formation porosity,formation thickness,fracture length,conductivity and soaking time,the water production decreases,the peak value of tracer production concentration decreases,and the recovery of tracer decreases;With the increase of formation pressure,fracturing fluid volume and production,water and gas production increase;With the increase of fracturing fluid volume,reversible tracer adsorption,fracture conductivity,initial water content and production,the tracer production concentration increases and the tracer recovery volume increases.(3)The main controlling factors of the peak concentration of fracturing tracer in horizontal wells are selected as follows: formation permeability,formation porosity,formation thickness,fracture length,fracture conductivity,fracture shape,gas tracer distribution coefficient and initial water saturation.The main controlling factors of tracer recovery are: formation permeability,formation porosity,fracture conductivity fracturing fluid volume,fracture morphology,gas tracer distribution coefficient,tracer adsorption type and production.