Hydrocarbon Accumulation Feature and Exploration Direction Selection: Taking M Block of Oriente Basin,Ecuador as an Example

Resumen

M block is a major hydrocarbon production area in Oriente Basin of Ecuador,while future exploration direction and targets of the block are unclear.Studies on hydrocarbon accumulation of the block should be carried out immediately.Based on the comprehensive drilling data,logging data and well test,the paper systematically analyzes 17reservoirs of M block and proposes the hydrocarbon distribution regulation and accumulation features,and figures out the future exploration area.The research shows that:(1)Structural background and fault have obvious controlling function on hydrocarbon distribution.Oil reservoirs all locate on the first structural belt near M fault and are mainly structural ones;(2)Trap fullness degree(FD) has obvious regulation in plane which decreases from north to south.The FD in northern part such as M4A_01,M4A_02,M4A_03,M4A_09,M_21,M_01are as high as 1,while the FD of M15in southern area is intermediate of 0.59,and the FD of M16in the south edge is 0which means no charging;(3)The OWC of the reservoirs step up from north to south;(4)Crude oil API degree decreases from north to south.All these accumulation features match the differential entrapment theory,based on which,a hydrocarbon accumulation model is established where hydrocarbon migrates along the structural belt and accumulates in a multistep way,i.e.,hydrocarbon sourced from the northern kitchen,migrated along the structural ridge and was entrapped in multistep traps.The northern part of M block,locates on the hydrocarbon migration path and close to source kitchen,has good accumulation condition and is the favorable area for future exploration.