This work provides the development, validation, and appli-cation of new decline type curves for a well with a finite conductivity vertical fracture centered in a bounded, circular reservoir. This work fills a significant void in the modern inventory of decline type curves. In particular, this work is directly applicable to production data analysis for cases taken from low permeability gas reservoirs.
Using an appropriate analytical solution for this case, we pre-pared "decline" type curves for FcD values from 0.1 to 1000 - individual type curves are generated for each FcD value using a range of reD values from 2 to 1000. The following "type curves" are provided:"Fetkovich" format rate-time decline type curves (con-stant pressure case): qDd versus tDd"Fetkovich-McCray" format rate-time decline type curves (equivalent constant rate case): qDd versus"Fetkovich-McCray" format rate-cumulative decline type curves: qDd versus NpDd
We provide an example demonstration of the methodology for decline type curve analysis using a field case of continuously measured production rate and surface pressure data obtained from a low permeability gas reservoir.
These solutions/type curves provide an analysis/interpretation mechanism that has not previously been available in the petroleum literature. Compared to field data, we find that the traditional type curve solutions for an infinite conductivity vertical fracture are typically inadequate - and, the new solutions for a well with a finite conductivity vertical fracture clearly show much more representative behavior. This validation suggests that the proposed type curves will have broad utility in the petroleum literature - particularly for applications in low permeability gas reservoirs.
The following objectives are proposed for this work:To develop and validate a series of decline type curves for a well with a finite conductivity vertical fracture centered in a bounded, circular reservoir.To provide a methodology for using decline type curves to analyze and interpret production or injection well performance for a well with a finite conductivity vertical fracture.To demonstrate these new type curves using continuously measured production data (rates and pressures).
In considering these objectives we note that we are strongly motivated to provide these tools in light of the current high level of activity in the analysis and interpretation of reservoir performance data acquired from low permeability gas reservoirs. We recognize that current methods based on the case of a vertical well with an infinite conductivity vertical fracture are overly-ideal for low permeability reservoirs and we must reconcile the need for a new decline type curve for a finite conductivity vertical fracture. This rationale is the moti-vation for this work.