FLUVIO-LACUSTRINE SANDSTONE DEPOSITION AND IMPLICATIONS FOR RESERVOIR DEVELOPMENT, DAAN FIELD, SONGLIAO BASIN, P. R. CHINA

J. Sneider¹, A. Harper², T. Liu², and J. Wang^3
1 Sneider Exploration
² MI Energy Corp
³ PetroChina Jilin

Since 2001, MI Energy - PetroChina partnership has drilled 31 wells at Daan Field, located in the central Songliao Basin, Jilin Province, northeast P. R. China. Interpretation of data from the drilling program has led to a new depositional model for the main reservoir objective Cretaceous FuYang fluvio-lacustrine sandstone, and indicates significantly higher OOIP potential for the field. The drilling program has also revealed an important new reservoir objective, the Cretaceous Putaohua sandstone, in the southern part of field.

• FuYang Sands
• General Description
• Depth 1700-2200m
• Porosity 10-18%
• Perm <1-30mD
• Facies: distributary channel, mouth bar, overbank, marginal-shallow lacustrine
• Original model – based on 40 wells prior to MI Energy – PetroChina drilling program
• Sands sourced from NW, W, SW
• Accumulated in narrow sand packages at high angles to NNE-trending Daan Fault
• OOIP 466MMBO
• New model - more consistent with the structural evolution of the field
• Young NNW-trending subsidiary faults post-date FY, and their effect must be stripped away to understand FY deposition
• Isopach mapping indicates FY sand packages trend N or NE, i.e. roughly parallel to NNE-trending Daan Fault system
• Deposition apparently controlled by older series of normal faults trending NNE, including Daan Fault (pre-reversal).
• Sand package cycles and facies
• OOIP up to 950MMBO
• Putoahua Sands
• Discovered by alert wellsite geologist in Da216-1 well, drilled in 2001
• Thinner than FY, but shallower and much better reservoir properties
• Depth 1250-1350m
• Porosity 20-25%
• Perm 8-75mD
• Facies: ??shallow lacustrine??
• Seismic isopaching suggests depositon controlled by shallow NW-trending faults
• Recent drilling confirms model
• Important reserves addition