Modeling of reservoir temperature upon preheating in SAGD wells considering phase change of bitumen

Evaluation of elastic property changes in Karamay oil sand reservoir during thermal stimulation

“…However, when the reservoir temperature is relatively lower than a critical temperature (softening temperature), the Karamay bitumen is viewed as the solid skeleton. For example, the bitumen during the phase of SAGD startup by water injection and early phase of steam circulation has a considerable elasticity, so Equation is not suitable for predicting the stiffness of bitumen under a low temperature. In this regard, Van Der Poel provided the engineers with a nomograph for determining the stiffness of bitumen by a large number of experiments.…”

“…It is actually one kind of unconsolidated sandstone reservoirs that is impregnated with high‐content solid or semisolid bitumen and is characterized by loose skeleton that is composed of interlocked solid grains . Bitumen is found filling pores and crevices of oil sand, but it plays different roles in oil sands of different regions: In the Karamay terrestrial sand‐in‐bitumen oil sand, it chiefly functions as cement as well as framework that can withstand considerable effective stresses, while in the Alberta marine bitumen‐in‐sand oil sand, it mainly functions as filler . No matter what kind of oil sands it is, the bitumen will make a significant contribution to the reservoir geomechanical response during thermal stimulation, because of its special mechanical behaviors that are very sensitive to temperature .…”

“…But the heated bitumen at more than 250°C is just like water, which possesses a perfect fluidity and bears no shear stress . In this regard, the existence of bitumen between solid grains makes a significant contribution to the elastic properties of oil sand, especially for the sand‐in‐bitumen oil sand, commonly seen in Karamay . The evaluation of reservoir deformation and its induced ground subsidence during thermal simulation is a focused issue for field engineers.…”

“…2,3 Bitumen is found filling pores and crevices of oil sand, but it plays different roles in oil sands of different regions: In the Karamay terrestrial sand-in-bitumen oil sand, it chiefly functions as cement as well as framework that can withstand considerable effective stresses, while in the Alberta marine bitumen-in-sand oil sand, it mainly functions as filler. [4][5][6][7][8] No matter what kind of oil sands it is, the bitumen will make a significant contribution to the reservoir geomechanical response during thermal stimulation, because of its special mechanical behaviors that are very sensitive to temperature. 9 The bitumen in virgin reservoir conditions possesses a dramatically high viscosity, which indicates a considerable elasticity/viscoelasticity at a low temperature.…”

“…11 In this regard, the existence of bitumen between solid grains makes a significant contribution to the elastic properties of oil sand, especially for the sand-in-bitumen oil sand, commonly seen in Karamay. [4][5][6] The evaluation of reservoir deformation and its induced ground subsidence during thermal simulation is a focused issue for field engineers. To obtain a good evaluation result, determination of elastic properties of oil sand reservoir is very important.…”