Taobao Oilfield has been producing viscous oil (μ = 1850 mPa.s @ 18°C) with sand for several years from a fine-grained reservoir on the west flank of the Songliao Basin in northern Jilin Province, China. The practices used closely follow the approaches developed in Canada in the last 15 years, but production is from a much shallower depth (-160m) and from a field that is fault-controlled and possesses some dip, rather than being stratigraphically controlled. The reservoir is composed of unconsolidated sands with high porosity (~35%) and high permeability (5 Darcy), suggesting a good prospect for CHOPS. The aggregate thickness of the sands is about 15 m with a formation thickness of 28 m; individual layers are 1-6 m thick, with an average of 4 m, substantially thinner than the beds usually exploited in Canada. Over 75% of the oil in place is in layers less than 5 m thick.
The first well started production in Aug 13, 1997. At present, there are 71 wells producing oil in Block 87 and Block 92. A crude oil recirculating system from the stocktank is used to keep oil flowing down the annulus to prevent blockage of the well. Conventional production using progressing cavity pumps is still low, the best wells are only producing approximately 25-30 b/d, but production can apparently be sustained for as long as 16 months.
Taobao Oilfield initiated CHOPS in approximately 22 wells in Blocks Bai 87 and Bai 92. The sand cuts range from 0.1 to 10% by volume, which is a broad range for a single field, compared to Canadian experience. Water cut is very reasonable, from as low as 0% to as high as 52%, with an average of 5-8%.
The article will review the geology and the production history of the Taobao CHOPS project to date. Petrophysical parameters and reservoir properties will be presented and compared to typical Canadian and Venezuelan information. Case histories from existing developments are used to illustrate how technologies developed in Canada have allowed the difficult heavy oil fields to be developed. Finally, the future direction for this CHOPS project is discussed, aiming at improving the oil production rate and the oil recovery. It appears that production gains are possible through improvements in operational practices.