Correlative modeling techniques to reducing uncertainties in a complex marginal field in the Niger Delta.

Abstract

Deterministic and probabilistic re-evaluation was used in handling predetermined six uncertainties in five wells in Isand reservoir. Results of low case (LC) modeled string showed that the I-sand reservoir is severely deformed by faults and this was confirmed with a predicted high case (HC) modeled string. When structure was sensitized at a bulk volume of 10,964STB with porosity of 0.266, water saturation of 0.43 and net to gross ratio (NTG) of 0.75 and initial oil formation volume factor (Boi) of 2.2bbl/stb, the resultant estimated stock tank initial oil in place (STOIIP) gave 5,892,752.65STB or the base case. The corresponding STOIIP for the low and high case are 5,198,470.887STB and 6,451,196.678STB. Results of deterministic analysis shows that the low case results gave a minimum value of 5.20MMSTB for structures and maximum value of 6.2MMSTB for water saturation. High case results revealed a maximum of 6.45MMSTB for structures and a minimum value of 5.69MMSTB for water saturation. Results of high, low and base cases were used to quantify some of the uncertainties in the volumetric estimation and subsequently in the probabilistic method. This work clearly shows the viability of the pragmatic approach used to quantify the uncertainty ranges in reservoir parameters and their impact on the statics volumes as well as recovery.
 

Keywords: deterministic, probabilistic, modeled, structures, water saturation, net to gross ratio