Du 84 block of Shu-1 area in the Liaohe Oilfield is located in Panjin city of Liaoning province of China. The production formation, Guantao, contains extra heavy oil with a depth of 530-640 meters. The reservoir is characterized in thick pay, high permeability and very active aquifer. The dead oil viscosity is 230,000 mPa.s at 50 °C.
Although Cyclic Steam Stimulation (CSS) process using vertical wells has been applied successfully in producing oil from the reservoir, the anticipated ultimate oil recovery is less than 29% of the original oil in place (OOIP). To enhance oil recovery beyond that of the CSS, physical and numerical modeling studies were carried out. The Steam Assisted Gravity Drainage (SAGD) process using the combination of the vertical wells and horizontal wells was proposed to be the follow-up process to CSS. Additional 27% recovery is anticipated with the proposed follow-up process. This gives a total recovery of 56%.
A pilot with four horizontal producers was implemented in the field. CSS was used initially in the horizontal wells for establishing the communication with the surrounding vertical wells. The pilot was then converted successfully to SAGD operations with horizontal wells as continuous producers and some of the surrounding vertical wells as continuous injectors. A total of 44,500 tonnes of oil has been produced so far during the last 12 months of SAGD operations. The field implementation process and pilot performance as well as the challenges with this project are presented in this paper.
This paper is the continuation of the work presented in 2003's CIM conference [1]. In that paper, a field pilot was proposed for testing Steam Assisted Gravity Drainage (SAGD) as a followup process to CSS based on the reservoir modeling work and feasibility studies. Two field pilot projects were constructed in 2003 in Du 84 block of Su-1 area in Liaohe oilfield. One pilot is producing from the Xinglongtai formation and the other one is producing from the Guantao formation. The pilot in the Guantao formation was converted to SAGD operations in early 2005 and the field results are encouraging. This paper is going to report the field performance for this pilot.
Steam Assisted Gravity Drainage (SAGD) process, which was described by Dr. R.M. Butler in the late 1970s[2], has been applied successfully for the production of bitumen and heavy oil since it was tested in the Underground Test Facility (UTF) in the Fort McMurray oil sand, Alberta, Canada[3]. Several commercial projects have been implemented in the field in Canada since then. Liaohe oilfield constructed the first SAGD pilot in China in 1996 in the Xinlongtai formation, which contains extra heavy oil at a depth of 750 meters deep from the surface. The pilot consisted of one stacked well pair and was operated for about one year and half. The suspension of the pilot test was due to (1.) not sufficient lift capacity provided by gas lift system; (2.) difficult in communication resulted from too large vertical separation between the injector and producer.
