We report the design, drilling, completion, flow back and production of lacustrine shale oil deposit (LSOD) lateral well in Guangdong block, Kongdian Formation in the Cangdong Sag, China.
Lacustrine shale oil from China features higher viscosity and density, low and fast varying GOR. The LSOD laterals are further complicated by the fast varying local geology.
We compare the key deposit and development features of the shale oil reserve in Cangdong Sag with other lacustrine reserves in China as well as the predominately marine shale oil reserves in North America. The difference between marine shale deposit in north America and lacustrine shale deposit in China are compared from completion design to production planning as well. Key parameters for completion design including the lateral length, number of stages and cluster spacing, fracing fluids and proppants loading per unit length, and key resulting post-frac parameters, such initial bottom hole shut-in pressure and flowing pressure, initial production, GOR of production as well as production curve over a period of more than 500 days are presented and compared to typical shale oil wells in lacustrine shale oil deposits as well as marine shale oil deposits in North America.
Just as lacustrine conventional oil dominates the oil reserves in China, lacustrine unconventional oil deposits dominate shale or tight oil. Unlike marine shale oil in the US, lacustrine shale oil deposits in China have quite unique geochemistry, and also greatly varying maturities and deposit environments.
The deposit environment affect the kerogen significantly. For example, high salinity deposit usually have oil-prone type I kerogen with significantly delayed and suppressed gas window and therefore high oil with low gas yield. The oil generated also features high amounts of cyclic ring hydrocarbons, i.e. naphthenic content.
This includes the heaviest shale oil ever reported, the Jimusaer Lower Permian deposit has density as high as 0.92g/cm3 or API 20, and gas to oil ratio (GOR) as low as 15m3/m3 or 90CF/bbl. The maturity characterized by vRo, Tmax and gas isotope measurement ranges from 0.80 to 1.05. The corresponding typical marine shale oil deposit usually have density at 0.84~0.8g/cm3 or API 36~45, and GOR from 3,000CF/bbl to over 2,000CF/bbl.