Hydrocarbon Reserves and Production Increment in Laminated Sand/Shale Reservoir From 3D Resistivity Measurements, Image Logs, and Magnetic Resonance Technology

Abstract

fax 01-972-952-9435. AbstractOil identification and quantification in low resistivity laminated sand-shale sequences is a major challenge for petrophysics and reservoir engineers; essentially because the thickness of the sand laminas is usually bellow the vertical resolution of the resistivity logging tool. The presence of this lithology generates electrical anisotropy where horizontal resistivity is highly affected by the conductivity of the laminar shale volume, while vertical resistivity is higher and more sensitive to the laminar sand electrical properties. Once identified the productive low resistivity problem the prediction of movable water, creates enormous uncertainty when it comes to decide if this laminated sand should be open to production in the well. All this issues have caused the underestimation of Oil-In-Situ volumes and the lost of thousands of oil production per day in the upper Misoa Formation Reservoirs in western Venezuela. The incorporation of resistive image logs in the geological analysis of upper Misoa Reservoirs, have shown the existence of thinly laminated sand-shale sequences with laminations of an inch thick and less. indicated that 90% of the water contained in the reservoir was irreducible, so it would not be produced.After completing the low resistive sands, production logging tests and well production showed 1300 BBD with 4% of water. This case opened a great opportunity in western Venezuela fields where this type of lithology can be found in most of the wells drilled trough Eocene reservoirs.

Evaluation of laminated shaly sand sequences in Ahwaz oil field using (via) high-resolution square logs

“…• NMR log (Coates et al 1999) • Resistivity anisotropy tools (Vielma and Vandini 2007) • Image log and analysis of high-resolution square logs (Tabanou and Antoine 1995) Therefore, it is desirable to use alternative methods which are less expensive from one hand and can secure reliable information about reservoir and hydrocarbon properties on the other hand. Among several challenges for identifying and evaluating laminated shaly sand (LSS), the following two are worth mentioning.…”