Study on temperature distribution along wellbore of fracturing horizontal wells in oil reservoir

The application of distributed temperature sensors(DTS)to monitor producing zones of horizontal well through a real-time measurement of a temperature profile is becoming increasingly popular.Those parameters,such as flow rate along wellbore,well completion method,skin factor,are potentially related to the information from DTS.Based on mass-,momentum-,and energy-balance equations,this paper established a coupled model to study on temperature distribution along wellbore of fracturing horizontal wells by considering skin factor in order to predict wellbore temperature distribution and analyze the factors influencing the wellbore temperature profile.The models presented in this paper account for heat convective,fluid expansion,heat conduction,and viscous dissipative heating.Arriving temperature and wellbore temperature curves are plotted by computer iterative calculation.The non-perforated and perforated sections show different temperature distribution along wellbore.Through the study on the sensitivity analysis of skin factor and flow rate,we come to the conclusion that the higher skin factor generates larger temperature increase near the wellbore,besides,temperature along wellbore is related to both skin factors and flow rate.Temperature response type curves show that the larger skin factor we set,the less temperature augmenter from toe to heel could be.In addition,larger flow rate may generate higher wellbore temperature.

Application of ARIMA-RTS optimal smoothing algorithm in gas well production prediction

Gas field production forecast is an important basis for decision-making in the gas industry.How to accurately predict the dynamic production during gas field development is an important content of reservoir engineering research.Reservoir numerical simulation is the most common method for predicting oil and gas production.However,it requires a lot of data to build an accurate geological model which is tedious and time-consuming.At present,many scholars have used machine learning and data mining methods to predict oil and gas production,but they have not considered whether the use of increasing production measures will affect the predicted results.Thus,ARIMA-RTS optimal smooth algorithm is the first applied to establish the prediction model of gas well production.According to the historical production data,the model is processed,the production differential autoregressive integral moving average(ARIMA)model in time series is established,then ARIMA model is combined with RTS(Rauch Tung Striebel)smoothing,and the production prediction model is constructed.RTS smoothing algorithm is an enhanced version of Kalman filter.The measurements are firstly processed by the forward filter,and then,a separate backward smoothing pass is used for obtaining the smoothing solution.The correctness of ARIMA-RTS model was verified with the actual production data.The results show that the prediction based on ARIMA-RTS model can accurately reflect the production performance of gas well.This method can effectively reduce the error caused by stimulation when predicting.When using the ARIMA-RTS model and the ARIMA-Kalman model to predict the production of the same gas well,the prediction accuracy of ARIMA-RTS model is higher than that of ARIMA-Kalman model in production wells with stimulation.Compared with that of the ARIMA-Kalman model,the mean relative error fitted by the ARIMA-RTS model is reduced by 46.3%,and the relative mean square error is reduced by 56.48%.ARIMA-RTS optimal smooth algorithm improves the prediction accuracy of gas well that uses stimulation.We therefore conclude that the ARIMA-RTS optimal smooth algorithm can help us better forecast the forecasting gas well production with stimulation,as well as other fuels output.