Monday, 20 July 2020, 12:35 p.m.–1:20 p.m., Austin, TX
Application of PVT and Petroleum Geochemical Analyses to Enhanced Oil Recovery in Resource Plays
Oil extraction techniques are estimated to recover just 5–7% of in-place oil using today’s technology. In response, a number of Enhanced Oil Recovery (EOR) techniques are being considered to boost this percentage and improve ultimate recoveries. One of the most promising techniques is “Huff and Puff” cyclic gas injection. In the Huff & Puff technique, separator gas from a nearby well or gas installation is injected (the Huff phase) into a depleted or partially depleted oil well, ideally at a high enough pressure to achieve miscibility. During the following soak period the miscible gas spreads through the formation, swelling the oil volume and decreasing its viscosity. After the soaking period, the well is put back on production (the Puff phase) with an expected increase in production rate due to the higher reservoir pressure and lower oil viscosity. The separated gas can then be sold or reinjected into another well to initiate a new Huff and Puff sequence. This process can be repeated as long as commercial quantities of liquids are extracted from each Huff and Puff cycle.
Because of the regional consistency of fluid properties in many shale plays, it is possible to predict regional trends in phase behavior once a calibration is established. We accomplish this by developing a database of PVT and geochemical measurements and mapping these trends across the plays. This illustrated work serves as a guideline for the selection and analysis of gas and oil samples and assists in the application of the results in a regional framework. Analytical objectives are focused on miscibility testing – both “first-contact” through swelling tests and “multi-contact” via slim tube studies. Representative recombined reservoir fluids and corresponding injection gases are collected from the field, or prepared in the laboratory, and run through an established laboratory program. Fluid compositions, densities, and viscosities are measured frequently and used in reservoir simulation models to evaluate the effectiveness of the Huff and Puff process.