Research On Temperature Prediction And Interpretation Model Of Horizontal Well

In the past decades, thousands of wells have been drilled horizontally and to obtain larger contact volume with the reservoir.Compare with vertical wells, downhole flowing status of horizontal wells are generally more complicated. Therefore, it is difficult to monitor horizontal wells' downhole flowing status.In recent years, as the development of measure technology, downhole permanent sensors were appeared, distributed temperature sensing(DTS), for example, sensors were assembled in horizontal wells as a part of well completion. This technology supply us real time, continuous and accurate temperature and pressure data of horizontal wells, it is possible to actually restore downhole flowing status through interpretation of real time temperature and pressure data measured by DTS.This paper start with reservoir percolation law and wellbore flow mechanism, based on material balance equation, momentum balance equation and energy balance equation, take a horizontal well in the center of homogeneity reservoir as the object of the research, establish horizontal well heat model that coupled reservoir and well, afterwards resolved for wellbore temperature and pressure under specific conditon by computer iterative calculation, then do following analysis:(1)analyse sensitivity factors of wellbore temperature under gas&oil production conditions, (2)influence of well deflection, (3) influence of gas&water production in part well section, (4)influence of skin factor.Based on forward model, this paper also research on the interpretation(inversion) model. The inversion model is based on the Levenberg-Marquardt algorithm. In the course of the study, the inversion objective function is defined, and the weight of the observed value of the objective function is analyzed, too. Then, by oil producing horizontal wells as the experimental object, the fitting error as the standard, analyse and select the optimal combination of observations, to determine the optimal input value of inversion model. On the basis of this, the temperature inversion model is established, which is based on the production of single phase oil, single phase gas, oil and water, oil and gas, and horizontal well considering formation damage.Through the forward model research of the horizontal wellbore temperature, main factors that influence of horizontal wellbore temperature we could gain. Inversion model research, by fitting horizontal wellbore temperature and pressure profile data, the real forecast of the horizontal well downhole flow come true. The inversion model also verify the reliability of the forward model. Temperature forward model and inversion model constitute a complete model of wellbore temperature prediction and interpretation, and a set of new ideas and methods of horizontal well monitoring are formed. At last, the model is applied to the field example, and it has achieved good results.