Abstract
The isolation failure of cement-formation interface is an important and urgent problem in oil production, while an effective way to solve it is to realize the integrated solidification and cementation of cement-formation interface (ISCCFI). In order to study the kinetics of ISCCFI with MTA (Mud Cake to Agglomerated Cake) method, the Diamond Differential Scanning Calorimetry Analyzer is adopted for experiments with dynamic method and isothermal method. The results show that there is a linear relationship between the solidification reaction temperature and the heating rate of ISCCFI with MTA method. For the first exothermic peak, the initial temperature, peak tip temperature and final temperature are 53 °C, 69 °C and 83 °C respectively, and the apparent activation energy of solidification reaction is 44.39×10-3 kJ.;mol-1, the natural logarithm of preexponential factor is 7.26, the solidification reaction order is 0.88. For the second exothermic peak, the initial temperature, peak tip temperature and final temperature are 83 °C, 92 °C and 114 °C respectively, and the apparent activation energy of solidification reaction is 99.14×10-3 kJ.;mol-1, the natural logarithm of preexponential factor is 24.77, the solidification reaction order is 0.94. The maximum solidification reaction rates at 50 °C, 75 °C and 90 °C are 0.09×10-3 s-1, 0.27×10-3 s-1 and 0.51×10-3 s-1 respectively. The kinetic models of ISCCFI with MTA method under different temperatures are established. It provides a theoretical and technical support for the isolation improvement of cement-formation interface.
Highlights
Along with the secondary development of old oilfields, the oilfield development in China and even the world mainly have two problems
The experimental evidences of integrated solidification and cementation of cement-formation interface (ISCCFI) with Mud Cake to Agglomerated Cake (MTA) method were obtained by mechanical evaluation, microstructural analysis and fluid dissolution test [17, 18]
The temperature of the first exothermic peak ranges from 50 °C to 100 °C, while the second exothermic peak ranges from 80 °C to 140 °C
Summary
Along with the secondary development of old oilfields, the oilfield development in China and even the world mainly have two problems. The cement sheath can be peeled off from the borehole wall so long as the mud cake exists This will cause microcracks between cement sheath and borehole wall, which reduces the bonding strength of cement-formation interface and provides a path or channel for fluids (oil, gas and water) from the reservoir or formation [6, 7]. In order to improve the bonding quality of cementformation interface effectively, a scientific concept of Mud Cake to Agglomerated Cake (MTA) was proposed [16] The experimental evidences of ISCCFI with MTA method were obtained by mechanical evaluation, microstructural analysis and fluid dissolution test [17, 18] This method has been applied in 23 adjustment wells in Daqing, Shengli, and Henan oilfields in China. Based on DSC (differential scanning calorimetry) test, the kinetic models of ISCCFI with MTA method were established
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