The Research On Development Technology Of Steam Stimulation By Horizontal Well In Offshore Heavy Oil Reservoirs

The current geological reserves of underground crude oil viscosity greater than 350 mPa.s are 739 million tons, accounting for 32% of Bohai heavy oil reserves. Cyclic steam simulation is widely used in onshore heavy oil fields at home and abroad, and its thermal recovery technology is relatively mature. So it is hopeful for cyclic steam simulation to be one of the effective development methods in offshore heavy oilfield because these heavy oilfields can’t be developed by the conventional water flooding and chemical flooding. Meanwhile, due to the impact of platform rstrictions, higher costs, drilling and completion, well type and boiler water rstrictions, there are many difficulties and challenges using cyclic steam simulation in offshore heavy oil. Therefore, it is necessary to carry out the development technology research of steam stimulation by horizontal well in offshore heavy oil reservoirsFirstly, the numerical simulation model of a typical cyclic steam simulation oil reservoir is established. On the basis, using numerical simulation methods studies the impact of geological parameters and the parameters of injection-production that effect the exploitation of heavy oil. On the base of cyclic oil production, using the method of orthogonal design on the the steam injection intensity, steam injection rate, bottom hole steam quality, steam temperature, soaking time and liquid producing rate these six factors do optimal orthogonal design. For the best result, the changes in the way and the incremental manner of the steam injection slug size are studied. And the incremented rate of each cycle steam injection is 20% with best results. Using numerical simulation methods studies the impact of the parameters of horizontal wells and pattern well spacing that effect the well pattern arrangement. And the well pattern and spacing of actual block is optimized. The study has shown that the optimal results are well pattern of positively straight line, horizontal well length of 300 m, row distance of 300 m.Based on the influence of different geological parameters and the parameters of injection-production for cyclic steam stimulation production, the oil production type curve is developed by introducing dimensionless parameter assemblage and the sensitivity of 12 parameters such as reservoir permeability, oil viscosity and liquid producing rate influencing the curve is analyzed. The results show that oil viscosity, reservoir permeability and production rate have higher effect on the curve while other parameters have little effect on it. The cases study indicate that the result from the type chart is of higher accuracy of prediction, with an error within 10%, compared with CMG simulation calculation, so it can be used in the oilfields.