Field Application of Newly Designed Non-Damaging Sealing Killing Fluid to Control Losses in Completion and Workover Operations in Western Desert, Egypt

Invasion of completion fluids to permeable reservoir formations causes different challenges including increase in water saturation, fine migration problems, well control problems and complicated fluid management. Such problems can result in severe reservoir damage leading to delay in production and increase in operation cost. This paper presents newly designed non-damaging, sealing and killing fluids (Salt Plug) customized to solve such challenges and engineered to control fluid invasion of completion fluid into reservoir. Formation damage might occur during subsequent well workover and perforation operations which requires non-damaging, sealing and killing fluids. The salt plug design incorporates a temporary plugging agent that form a physical barrier across formation face or within formation matrix. Consequently, the plug minimizes formation damage and fluids invasion into reservoir formation during well flow back. Due to its water solubility characteristics, the plug can be easily cleaned up using unsaturated brine water after remedial workover operations. Salt plug was used in reservoir formation in a wide fluid density range of 10.3 - 15.0 Pounds per Gallon (ppg) based on brine type and sized particles concentration to prevent fluid loss during remedial completion operations. This plug was applied in field proving its success in more than 10 deep wells and was successful to seal off void spaces around perforation tunnels and holes up to 0.5 inch. It can be customized to meet project requirements through proper selection of the particle-size distribution (PSD) of salt. Filter cake associated with salt was easily removed with start in production phase with a minimal differential pressure of 20-50 Psi to unload the well. This pill was effective replacing conventional water insoluble calcium carbonate (CaCO3) bridging solids with water soluble sized salt bridging solids which are less aggressive breaker systems.

Salt extrusion kinematics: insights from existing data, morphology and InSAR modeling of the active emergent Anguru diapir in the Zagros fold and thrust belt, Iran

Emergent salt diapirs are highly mobile geological objects, kinematics of which pose essential pure and applied problems for geologists and engineers. Movement and deformation of buried salt after its ejection onto the surface is a multivariable process which is susceptible to plenty of intrinsic and ambient factors. As a result existing data acquisition approaches give extremely variable movement rates for subaerial salt extrusions. The Anguru diapir in the Zagros fold and thrust belt (ZFTB) is a typical emergent intra-anticlinal salt plug which demonstrates a very recent activity, and hence is selected to be studied for quantifying salt kinematics under relatively well-defined physical conditions. We used Interferometric Synthetic Aperture Radar (InSAR) time-series data to evaluate surface displacement over the salt dome by constructing 236 interferograms derived from 47 Envisat ASAR (time span: 2003-2010) and 12 ALOS PALSAR (time span: 2006-2010) images, which combined with other lines of evidence, suggest a very recent extrusion history. The maximum LOS (Line Of Sight) displacement rates of the diapir surface are -2.6 and +1.4 cm a-1. Modeling of the Anguru salt plug surface suggests a bilobed pattern of LOS movements which allows interpretation of the interferometric patterns observed over active upwelling (doming) or downwarping structures.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5413388

Spatiotemporal variation of Van der Burgh's coefficient in a salt plug estuary

Salt water intrusion in estuaries is expected to become a serious global issue due to climate change. Van der Burgh's coefficient, K, is a good proxy for describing the relative contribution of tide-driven and gravitational (discharge-driven and density-driven) components of salt transport in estuaries. However, debate continues over the use of the K value for an estuary where K should be a constant, spatially varying, or time-independent factor for different river discharge conditions. In this study, we determined K during spring and neap tides in the dry (< 30 m−3 s−1) and wet (> 750 m−3 s−1) seasons in a salt plug estuary with an exponentially varying width and depth, to examine the relative contributions of tidal versus density-driven salt transport mechanisms. High-resolution salinity data were used to determine K. Discharge-driven gravitational circulation (K ∼ 0.8) was entirely dominant over tidal dispersion during spring and neap tides in the wet season, to the extent that salt transport upstream was effectively reduced, resulting in the estuary remaining in a relatively fresh state. In contrast, K increased gradually seaward (K ∼ 0.74) and landward (K ∼ 0.74) from the salt plug area (K ∼ 0.65) during the dry season, similar to an inverse and positive estuary, respectively. As a result, density-driven inverse gravitational circulation between the salt plug and the sea facilitates inverse estuarine circulation. On the other hand, positive estuarine circulation between the salt plug and the river arose due to density-driven positive gravitational circulation during the dry season, causing the upstream intrusion of high-salinity bottom water. Our results explicitly show that K varies spatially and depends on the river discharge. This result provides a better understanding of the distribution of hydrographic properties.

Spatiotemporal Variation of Van der Burgh's coefficient in a salt plug estuary

Saltwater intrusion in estuaries is expected to become a more serious issue around the world due to climate change. Van der Burgh's coefficient, K, is a good proxy for describing the relative contribution of the tide-driven and gravitational components of salt transport in estuaries. However, debate continues over the use of K value for an estuary where K should be constant or spatially varying or a time-independent factor for different river discharge conditions. In addition, whether K functions in an inverse salinity gradient area of a salt plug estuary has not been examined thus far. In this study, we determined K during spring and neap tides in the dry (<30 m−3 s−1) and wet (>750 m−3 s−1) seasons in a salt plug estuary with an exponentially varying width and depth to examine the relative contributions of tidal versus density-driven salt transport mechanisms. High-resolution salinity data were used to determine K. Gravitational circulation (K~0.8) was entirely dominant over tidal dispersion during spring and neap tides in the wet season such that salt transport upstream was effectively reduced, resulting in the estuary remaining in a relatively fresh state. In contrast, during the dry season, K increases gradually seaward and landward (K~0.74) from the salt plug area (K~0.65), similar to an inverse and positive estuary, respectively. As a result, density-induced inverse gravitational circulation between the salt plug and the sea facilitates inverse estuarine circulation. On the other hand, positive estuarine circulation between the salt plug and the river area arose due to density-induced positive gravitational circulation induced by the tide during the dry season, causing the intrusion of high-salinity bottom water upstream. Our results explicitly show that K varies spatially and depends on the river discharge. This result provides a better understanding of the distribution of hydrographic properties as well as the distributions of pollutants, nutrients and biota within large estuaries.