The South Belridge Diatomite is a low permeability, high porosity, permeability, high porosity, hydraulically-fractured reservoir. Infill drilling of the South Belridge field focused attention on fracturing. The three topics covered in this paper are a review of re-fracturing performance, an estimate of existing performance, an estimate of existing hydraulic fracture length, and application of analytical and simulation models to analyze and predict reservoir behavior. predict reservoir behavior. Re-fracturing treatments successfully extended existing fractures. The productivity of seventeen wells productivity of seventeen wells increased 17% for eighteen months after stimulation. The fracture half-length of existing wells is estimated to be 115' [35 m], while the no flow boundary is known to be 165' [50 m]. The half-length is calculated based on the productivity of 20 wells and their productivity of 20 wells and their reservoir pressure profile after 5 years of depletion. It is assumed that the reservoir is still in transient linear flow.
An areal simulation is undertaken which validates the application of linear flow equations to this reservoir. The simulation is also used to predict. the incremantal production due to longer fractures in new wells. As the fracture length increases, the marginal production benefit decreases. production benefit decreases
The South Belridge Diatomite is a 1600' [500 m] thick, low permeability, high porosity reservoir 40 miles [64 km] porosity reservoir 40 miles [64 km] west of Bakersfield, California. Primary wells on 2.5-acre [10 E+3 m2J Primary wells on 2.5-acre [10 E+3 m2J spacing were completed with 3-5 hydraulic fracture stages. Infill drilling to 1.25-acre [5 E+3 m2] spacing commenced in earnest in 1987. In anticipation of the additional drilling and completion of roughly 400 wells and 1600 hydraulic fractures, attention was focused on hydraulic fractures and the fluid flow model for the reservoir.
Primary production from Diatomite wells Primary production from Diatomite wells cannot be modelled with exponential or harmonic decline curves. The instantaneous exponential decline rate is continuously decreasing faster than even in the harmonic case.