Prediction of Formation Pressure Gradients of NC98 Field-Sirte Basin-Libya

The prediction of formation pore pressure and fracture pressure gradients is a significant step towards the drilling plan. In this study, the formation pressures of twelve wells from NC98 field-Sirte Basin (Waha Oil Company) were calculated by employing empirical methods, Eaton’s equations, that depend on the real drilling and well-logging data. Regarding the results, the normal pore pressure in the NC98 field in Sirte basin is 0.437 Psi/ft, and it is extending from the top of the wells in the investigated area to 7,000 ft. A subnormal to normal pore pressure zone is noticed in the interval of 7,000 ft. to 9,000 ft. Then, slightly subnormal to somewhat abnormal (overpressure) region is seen from 9,000 ft. to 11,200 ft. Beyond to that depth and down to the top of the reservoir, the overpressure zone was clearly observed. Based on the results, the casing setting depth and the equivalent mud weight were simply determined for the area of study

Effect of aromatic ring, cation, and anion types of ionic liquids on heavy oil recovery

Surfactant/alkali flooding is one of the best chemical flooding methods to enhance oil Recovery Factor (RF). In this research, Ionic Liquid/Alkali (ILA) mixtures were chosen to address the chemical injection technique. The selected Ionic Liquids (ILs), [EMIM][Cl], [THTDPH][Cl], [EMIM][Ac], [BzMIM][Cl], [DMIM][Cl], [BzMIM][TOS], [dMIM][TOS] and [MPyr][TOS], were introduced to investigate their efficiency in improving the extraction of heavy oil (14o API) from an unconsolidated sand pack at room conditions. Second, these ILs were mixed with synthetic formation brine (3.37 wt. % salts)/alkali (Sodium Bicarbonate [NaHCO3]). Then, 1 Pore Volume (PV) of these composites were injected and flushed with 2 PV of formation brine. The study discussed the influence of cation type, anion type, the structure of the ILs, and the effect of combining ILs and alkali on the RF. The results revealed that these ILs are efficient chemicals for enhancing the RF. ILs with shorter alkyl chain and more aromatic rings are noticeably efficient in enhancing the RF. Finding the right composition ([DMIM][Cl] + NaHCO3) of the chemical slug could increase the additional RF up to 31.55 (% OOIP). The recovery factor results supported by the effects of IL types on the viscosity, Surface Tension (SFT), and Zeta Potential (ZP) supported

History matching of experimental and CMG-STARS results

Abstract At present, chemical flooding is one of essential enhanced oil recovery methods. In this study, three core flooding experiments (brine flooding, Alkaline, and Alkaline + Ionic Liquid slug flooding) were selected for history matching using CMG-STARS. Depending on the composition of the chemical slug, two pore volumes were injected into the porous medium to enhance the RF of heavy oil (14° API). We observed that the most challenging part of building up the model was relative permeability curves. So, the relative permeability values were tuned to end up with a successful match of cumulatively produced oil and water cut. Finally, history matching is significant to apply a wide range of assumptions and upscale the experimental results