Calculation Of Additional Reserves Of Chang 2 Reservoir Of Yanchang Formation In L29 Well Area Of The Ordos Basin

L29 block is located in the southeastern of Ordos basin,Chang2 reservoir mainly distribute in underwater distributary channel of delta front.the oil-bearing sand body of Chang2 reservoir is more,composite is a typical lithologic reservoir,Meanwhile,the characteristic of reservoir is oil-water mix storage and no obvious edge on bottom water,low formation energy.So,the development of Chang2 reservoir is difficult.To investigate probing geologic reserves of oil in L29 block,making development plan,calculate proven oil geologic reserves,and to develop conceptual design and economic evaluation,in order to improve the oilfield development level,is of great significance.Volume method mainly used to calculate oil geological reserves.When hard to volume method to calculate oil geological reserves,but should adopt dynamic method and probability method.Chang2 reservoir of L29 well district is at the early stage of scrolling development at present,adopting volume method to calculate reserves is reasonable.Using volume method for reserves calculation of Chang2 oil reservoir group,the Chang2 oil reservoir group of L29 block is divided into two reserves calculation unit of Chang21 and Chang22 at vertically,which is as one calculation unit in the plane.Calculating oil geological reserves of Chang2 oil reservoir of L29 block is 898.41 ×10~4 t(1067.00× 10~4 m~3),dissolved gas geological reserves is 0.71 × 108 m~3,superimposed petroliferous area is 25.56 km2.According to the reservoir types and reservoir property(reservoir physical properties,fluid properties,rock and fluid properties)and development conditions,the oil technology recovery ratio under natural energy mining is 10%,the oil technical recoverable reserves is 89.84 × 10~4 t(106.70 × 10~4 m~3),the dissolved gas technology recoverable reserves is 0.07× 10~8 m~3.The evaluation method of economy recoverable reserves mainly include cash flow method,the second is economic limit method and analogy method.According to production dynamic data of Chang2 oil reservoir of L29 block under natural energy,comprehensive analysis that the economic recovery is 8.4% by using economic limit method and cash flow method,oil economic recoverable reserves is 75.60 × 10~4 t(89.79 × 10~4 m~3).According to exploration and development degree and geological research,the reserves category is defined as proved developed reserves in L29 block.Comprehensive assessment indicates that L29 block is a conventional and small oilfield,is the lithologic reservoir of elastic and dissolved gas driven,where the output is low,reserves abundance is also low and sulfur elements in oil is less.The Chang2 reservoir buried depth is in middle-shallow and the characteristic of reservoir physical properties is low permeability and low porosity.By economic and technical indexes,the Chang2 reservoir of L29 block belong to low benefit oilfield.But exploitation technology and managerial approach is fit to the oilfield production,after-tax internal rate of return which is 15.94% greater than the industry benchmark rate of return which is 12%.Therefore,the oilfield can get a certain economic benefits.