Maximizing opportunities for data collection should always be a priority. Since many appraisal well programs are being delayed or cancelled, and data collection requests are being deferred in newly-drilled wells, finding innovative opportunities to collect data from available wellbores is critical. In the subject well, multiple layers were planned for perforation and commingled production. The challenge was that the individual layer pressure depletion history and fluid quality were unknown.
To overcome the challenge, cased hole pressure and fluid sampling with straddle packers was planned during the workover. A pulsed-neutron log(PNL) was run over the zones of interest to know the current saturation status of each layer. Based on PNL results, a cased-hole fluid sampling and pressure measurement program was implemented. The plan was successfully executed and completed in a multi-layered environment with a wide range of pressure variation.
The data collected was used as an input for a cased-hole ICD installation, to maximize recovery through commingling multiple layers in the wellbore. The better producing zones could be targeted from other surrounding wells, however the other less developed layers could only be exploited from the current wellbore. Based on the cased hole pressure and sampling data, selected layers were perforated and significant production gain has been achieved. One untested layer was successfully sampled which could not be tested earlier. Earlier attempts to sample this layer were not possible in the open hole due to poor hole conditions and well stability issues.
This methodology to acquire the formation pressure and downhole fluid samples in a cased hole multi-layer environment with a wide range of pressure variation among each layer, reduces the risk of comingling production from layers with significant pressure variation, it minimizes the risk of hole stability in high-angle wellbores, and eliminates the costly drilling rig time consumed in openhole sampling.