R.H. Morales; A.S. Abou-Sayed; A.H. Jones; A. Al Saffar; R.A. Schmidt
Presented at: SPE Annual Technical Conference and Exhibition, Houston, Texas, September 1984.
Analysis of the Injection Test for a Waterflooding Experiment and Interpretation of the Accompanying Processes
Abstract
A 30 day waterflooding test in which seawater was injected into two production zones (A and B) of an oil producing limestone reservoir is analyzed. During testing the flow rates were varied to maintain constant tubing head pressure. Injection rates were recorded for three levels of constant tubing head pressures (THP): initial (THP = 990 psig), intermediate (THP = 1240 psig), and final (THP = 1490 psig). The purpose of the analysis was to detect the possible occurrence of a fracture. A radial fluid possible occurrence of a fracture. A radial fluid flow technique was utilized to analyze the pressure-injection behavior. The analyses disclosed a pressure-injection behavior. The analyses disclosed a change in the formation’s ability to transmit fluids. Rock mechanics analyses were utilized to quantify the changes in in situ stress due to water flooding effects (i.e. pore pressure buildup and temperature decrease). The later analysis disclosed that the bottomhole fluid pressures exceeded the modified minimum in situ stresses at the intermediate and final pressure levels. Both, the increase in fluid transmissibility and the bottomhole fluid pressure rise above the modified minimum in situ stress indicated the occurrence of fracture. A possible fracture geometry was obtained by means of 2-D and 3-D hydraulic fracturing simulators.