Numerical Simulation on the Impact of Temperature Behavior for Cement Hydration for the World's First Offshore Methane Hydrate Production Test

Abstract

The world's first offshore production test of the methane hydrate (MH) project was successfully carried out in the deepwater Nankai Troughin 2013. In February and March 2012, a production well and two monitoring wells were drilled and cemented to deploy temperature monitoring systems for which a combination of distributed temperature sensing (DTS) and array-type RTD (Resistance Temperature Detector) was employed.For cement hydration, the chemical reactions are exothermic in nature so that a measureable temperature increase will be observed once the heat is released. With a typical cement system in wellbore configuration, this temperature increase could result in MH dissociation prior to the production that may have some impacts on the extraction of actual methane gas. Additionally, potential problems of thermally induced cracking are another concern.To evaluate the thermal effect from the cement heat to MH, a 1D numerical model of cement hydration is developed based on the radial heterogeneity of thermal properties. The temperature data acquired during cementing stage is used as the input data for the model, and the parameters such as activation energies for the cement hydration heat correlation in the model are determined. It was shown that the variation of simulated temperature from different MH saturation within the upper MH zone is so small that a reliable estimation of MH saturation becomes difficult while the estimated MH saturations from temperature data inversion in the lower MH zone are relatively high. A sensitivity study is also performed to understand which parameters in the developed model most significantly influence the temperature during the different stages of the cement hydration, respectively.

Thermal responses of a gas hydrate-bearing sediment to a depressurization operation

“…Moreover, DTS provides robust measurements and higher spatial resolution (1 m), and therefore it was selected as sensors for the production well, in which larger changes of temperature are expected. DTS was also used for long-term measurement in the monitoring boreholes, in which measurements over approximately one and half year-longs were planned, to record the effects of cement hydration and its relaxation, 76,77 static geo-thermal conditions, 78 effects of hydrate dissociation, and recovery of temperature aer the production test.…”

“…17, it is interesting that data from the monitoring and production boreholes consistently show that some anomalies occurred at a certain depth when sand production occurred 143 hours aer the ow started. 24,76 In the case of monitoring boreholes, a rapid, relatively large temperature drop was observed at 18 and 20 mBTMHCZ. Aer the production test, quick recovery of temperature with some rebound occurred in the same layer.…”

Thermal Diffusion Characteristics in Permafrost during the Exploitation of Gas Hydrate

“…From the previous experience [12], the onshore production of hydrate in permafrost is the road to the offshore production test. Although some researchers made the in situ temperature measurements and numerical simulation of temperature behavior in offshore methane hydrate production [49,50], the preliminary analysis could not fully explain the temperature distribution behavior and its affection. Because most marine gas hydrates occur in the submarine landslide zones, so the reservoir framework and reservoir stability would be affected by the maximum temperature and temperature distribution around the wellbore during operation of drilling, well completion, and well cementation in offshore hydrate production.…”