陆相页岩油水平井光纤DTS反演与产液剖面动态表征OA

To improve the interpretation accuracy of fluid production profiles in continental shale oil horizontal wells after volumetric fracturing and to address the challenge of synchronously and quantitatively identifying oil production,water production,and water cut for each fracturing stage under oil-water two-phase production conditions,this paper focuses on shale oil horizontal wells in the Chang7 member of the Qingcheng oilfield,Ordos basin.Using long-term monitoring data from distributed temperature sensing(DTS),a coupled heat transfer model integrating fracture,reservoir,and wellbore for oil-water two-phase flow is constructed.Water cut is incorporated as an independent inversion parameter into the solution framework,and a phase-separated fluid production inversion method based on the particle swarm optimization(PSO)algorithm is established.The results are validated with logging-based sweet spot classification,fracturing treatment parameters,chemical tracer data,and production logging tool(PLT)surveys.The results demonstrate that:①The phase-separated inversion method can simultaneously invert oil and water production for each stage using DTS temperature profiles.For two validation wells,the average relative error in oil production is 8.7％,that in water production is 10.0％,the mean absolute error in water cut is 5.7 percentage points,and the coefficient of determination R2 is 0.89,meeting the accuracy requirements for production performance evaluation.②The normalized sensitivity coefficient of water cut to the DTS temperature profile is 1.48,lower only than that of single-stage liquid production and reservoir permeability.When water cut increases from 0 to 90％,the average variation in the DTS temperature profile ranges from 0.3 to 0.8℃,which is about 3 to 8 times the DTS measurement accuracy,indicating that the temperature signal possesses the physical identifiability to support independent water cut inversion.③The fluid production contribution of shale oil horizontal wells in the Qingcheng oilfield exhibits significant spatial heterogeneity.Statistics from 208 fracturing stages in 6 wells show that approximately 39.4％of the stages contribute 74.8％of the total fluid production,about 18.8％of the stages contribute less than 2.0％,and the high-oil-production stages dominantly control the total oil output.④There is a clear correspondence between the water cut of each stage and the sweet spot type:the average water cut of Class Ⅰ sweet spot stages is about 18％,that of Class Ⅱ sweet spot stages is about 42％,and that of Class Ⅲ non-sweet spot stages is about 71％,indicating that uniformly distributing the wellhead water cut or splitting it in proportion to total fluid production cannot reflect the true inter-stage differences.⑤The fluid production profile exhibits a staged evolution with production time,transitioning from"heel pressure-differential control"to"sweet spot quality control"and then to"dynamic relative equilibrium."The stimulation intensity has a significant amplification effect on the release of reservoir potential.It is concluded that the phase-separated fluid production inversion method based on fiber-optic DTS can convert temperature monitoring data into stage-wise,phase-separated,and dynamic production information,providing a quantitative basis for identifying low-efficiency stages,water shutoff and conformance control,re-fracturing stage selection,and fracturing parameter optimization.