Horizontal Well Production Profile Interpretation Based On Distributed Temperature Sensing

As the majority of oilfields in our country have been in high water cut period,how to figure out the location of water cresting and then to shut off water has been a difficulty perplexing three major oil companies in our country at present.With the rapid development of optical fiber measurement technology in recent years,the fiber-optic distributed temperature sensing technology(DTS)has been gradually mature.It can detect subtle temperature changes,provide real-time,continuous and accurate temperature data,So by the means of measuring temperature and pressure distribution directly through DTS technology and inversing them,the horizontal well production profiles can be obtained to get production performance information and to realize the quantitative interpretation of water location,which avoids many problems of the conventional production logging,such as difficulty,time-consuming,big error as well as high cost.Thus,this thesis studies on the theory and method of the horizontal well production profile interpretation based on DTS,which provides technical support for solving the difficulty of finding and controlling water in horizontal wells in our oil fields for several years.First,the multiphase flowing horizontal well temperature model is based on the reservoir percolation,wellbore flowing and thermal mechanisms.Mass conservation,momentum conservation and energy conservation,as well as subtle thermal effects(thermal expanding,heat conduction,heat convection and viscous dissipation etc.)and formation damage to describe the heat conduction both in the reservoir and wellbore,are considered so that the temperature profiles of formation and wellbore is included.By resolving the hybrid model of reservoir percolation,wellbore multiphase flow,and the thermal model of formation and wellbore,and analyzing the effects of inflow fluid types,permeability,water cut,well trajectory and well completion pattern etc.on temperature distribution,the interpretation charts that describe the relationship between water location and temperature distribution can be obtained.Next,considering the compound temperature profile prediction model as the horizontal well forward model,and the permeability as the target parameter,the inversion model based on the Levenberg-Marquardt(L-M)inversion method and the Markov chain Monte Carlo(MCMC)inversion method is established,which can best match the tested data of temperature and pressure to make the objective function reach minimum.The permeability and production profile of horizontal well are gained through a serious of forward and inversion calculations.Bottom water reservoir horizontal well production profile is taken for example.The two inversion methods are compared in terms of advantages and disadvantages.The inversion results indicate that the MCMC method is better than the L-M method.Then,according to the horizontal well production profile interpretation process presented,the production profile is interpreted.The interpretation includes different water forms(one is water cresting from the bottom water reservoir and the other is water and oil in the same layer,water and oil produced in the same depth),different water position,different horizontal well production contribution and different permeability distribution.The inversion results show that generally horizontal well temperature and pressure distribution can fit well,and the inverted formation permeability is close to the reality.In addition,the horizontal well production profile is accurate.All these results above can demonstrate that the horizontal well production profile inversion method can reflect the reality.This method can help interpret the production contribution of each horizontal wellbore section,and can implement quantitative interpretation of water location.At last,based on the mechanism example,and the horizontal well production profile interpretation theory and method presented in this paper,the production profile interpretation and water location of a actual horizontal well are obtained.The temperature and pressure data are measured by DTS test.Through the comparison with the conventional production logging,the method adopted in this paper is more reliable.The research findings can provide direct technical support for finding and blocking water in the horizontal well.At the same time,they can guide the horizontal well production performance optimization and horizontal well completion optimization.The study results have wide application range and excellent prospects,which shows the important and realistic meaning for the stabilization of oil and water control,as well as the improvement of comprehensive production benefit.