This paper presents the results of scaled model experiments which were conducted to study the possible application of horizontal wells and were used to assess and compare the configurations of horizontal/vertical wells for a type reservoir which is characterized by high viscous oil (11,000 mPa · s at reservoir temperature). The mobility of high viscous oil is limited, so conventional vertical well steamflood is uneconomical. But reservoirs of this type are common in China, thus it is imperative to develop recovery strategies which are likely to succeed in the field, which was the objective of this research.
The scaled model had two vertical wells and four horizontal wells which corresponded to injectors or producers. Experiments of many types of horizontal/vertical well configuration were conducted. Some of which gave favorable results. The horizontal injector-horizontal producer configuration was the best one for the high viscous oil of this study. Horizontal well steamflood can be effective for reducing or preventing steam override and steam channel, the final oil recovery was 54% compared with 35% for a baseline experiment using vertical well steamflood. When steam flow rate increased from 140 cc/min to 170 cc/min, the final oil recovery increased from 57 % to 62%. The preheat phase by steam circulation further improved the final recovery to 78%. The SAGD (Steam Assisted Gravity Drainge) process of horizontal injector-producer configuration not gave good results, it was a very slow process and it's effective drainage area was smaller. The steamflood of vertical/horizontal well configuration was unsuccessful. Temperature measurement and theoretical analysis were used to interpret the results obtained.