Two mudstone dikes formed in the M1-SS layer of D-F oilfield

Oriente Basin

Ecuador

were studied to characterize their vertical and planar distribution based on drilling

logging and seismic data

and to analyze the factors that controlled their formation in respects of sedimentary setting and differential compaction process.Their impact upon the distribution of oil accumulations in the oilfield was also discussed in the paper.Both NW-SE-trending dikes are characterized by higher clay content in well logging and low amplitudes in seismic data.The study suggests that the dikes correspond to hybrid sand-mud flat microfacies in a tide-dominated estuarine environment and have higher clay content than surrounding sand flat and sand bar microfaices.Therefore

after differential compaction

the sand-mud flat ended up with a thinner thickness of M1-SS and even formed tiny faults at the edge of dikes.Besides

the presence of the dikes affected the reservoir heterogeneity and decreased the continuity of the sandbodies in M1-SS

thus blocked lateral migration of hydrocarbons.As a result

the oil accumulation to the east of the source rock-rooted fault was compartmentalized into five small reservoirs.