Research And Application On The Gradation And Classification Of Difficult-to-produce Oil Reserves In Liaohe Oilfield

The difficult-to-produce oil reserves are poor quality of resources,complex distribution characteristics,and difficult to develop economically and effectively.It is a relative concept,in different oil prices,different mining models,different management systems,different operating mechanisms will have different results.As of the end of 2014,The difficult-to-produce Oil reserves in Liaohe Oilfield are 130 units of 1.84 tons,is 43% of undeveloped reserves.In this paper,the reserves are divided into four types,low permeability sandstone reservoir,steam injection heavy oil reservoir,special lithological reservoir and fault block reservoir.The horizontal classification of difficult-to-produce reserves is realized.Four methods such as aggregative indicator,osculating value,dispersion rate,optimal cut methods are applied to create classification standards.Perfect evaluation and screening methods,and vertical classification reservoir becomes reality.Therefore,the technical standard of screening evaluation for difficult-to-produce reserves was established.On the basis of classification research,the economic limits of investment,cost and other parameters are studied for the first time,and the economic limit rate under different oil price of reservoirs in12 types(three grades in four types)is determined,the highest and most sensitive is the special lithological reservoir,if oil prices fall by $10/bbl,the economic limit rate will increase by 20%,and the gap between different class in same type is 200 tons.On the basis of the above research,the overall plan for difficult-to-produce reserves of Liaohe Oilfield is compiled scientifically and rationally.Planning the use of reserves of 94 million tons,arranged in 970 wells,drilling footage of 2 million 296 thousand meters,is expected to be built with an annual capacity of 787 thousand tons.