A Decision-Making Workflow in Simultaneous Formation Fluid Flow Profile Modelling During Stimulation and Post-Stimulation Well Tests in the Low Permeability and Heavy Oil Environments

Abstract

Abstract The method presented in this paper shows practical experiments in initial evaluation of formation zones productivity of newly completed wells in challenging heavy oil and low permeability environments. Results were obtained by implementation of stage-based downhole surveyance during the long well stimulation process, whereas, acquired data information was used in the modelling software, and the fluid intake and inflow formation parameters were simulated. The outcome of this work led to the correct choice of future decisions. The initial production well testing in a low productivity and heavy and viscous oil environments require special planning, stimulation and the down hole tools. The choice of well equipment and logging tools was limited due to low flow rates, coiled-tubing operations and exposure of tools to acid injected into the wellbore. The sequence of downhole data acquisition was designed to enable obtaining the information for planning the next stage of well operations. The temperature and pressure data were collected in memory gauge running simultaneously on coiled tubing in two newly drilled wells. The downhole, surface, formation and well information were used in the numerical simulation of fluids flow injected during stimulation and in the production profiles. Two cases are presented in this paper: one well was completed across open-hole carbonate zone with a low permeability, and the second well completed with a perforated casing across heavy oil formation zones. Both wells were attempted to lift naturally with nitrogen using coiled tubing. Downhole and surface parameters (temperature/pressure) were recorded for both wells in shut-in, during stimulation, post-stimulation and during production well test conditions using a downhole gauge. The availability of a full set of data from the gauge made it possible to integrate the data into the modelling software enabling the simulation of formation flow in-take and inflow profiles during various stages of testing. The first results showed that majority of acid was injected into a lower part of formation zone, with production profile showing a similar pattern, and therefore, decision was not to conduct any further stimulation. Interestingly, the second well surface data showed that fluid production stopped during nitrogen lifting during the test after multi-stage stimulation with ammonium chloride (NH4CL), hydrochloric acid and solvent. The output helped to diagnose the active formation zone (lower perforation) and profile contributions that wouldn't be possible in current well conditions. Novel/Additive Information: The results of this paper show integration of planning, design of well stimulation with simultaneous acquisition of downhole data that is used in the modelling software for quantitative flow profiling. This approach will be helpful for understanding active flow zones of formation in challenging well environments, where the choice of well equipment and downhole tools is limited.