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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Real-Time Petrophysical Integration of NMRWD, FPWD and LWD Triple-Combo in Slim Holes

Yousef M. Al-Shobail1; Doug Seifert1; Ridvan Akkurt1; Saleh Dossari1

(1) Reservoir Characterization, Saudi Aramco, Dhahran, Saudi Arabia.

Real time petrophysical analysis in slim hole wells is complicated by the presence of heavy oil and tar zones and the availability of the slim logging tools. The reservoirs in this case study contain heavy oil and tar in the flanks, and accurate knowledge of viscosity trends becomes essential for the placement of water injectors. The “tar mats” create a permeability barrier between the water and desired oil. Optimal pressure support and oil recovery from water injection into these reservoirs requires the well trajectory be kept as deep as possible in the producible oil column while at the same time, not encountering the heavy oil or tar mat.

The geometry of these heavy oil and tar deposits have been mapped with previously drilled vertical wells that act as control points. These wells indicate that the tar mat is neither flat nor uniform in thickness. Additionally, the well data show an increase in the oil viscosity with depth from the field oil to the tar mat. Injectors need to be placed in the injectable zone close to the heavy oil tar boundary to have a good pressure support and obtain desired injection rates and sweep efficiency.

Recent developments and innovations in 4-¾” Logging While Drilling (LWD) technology are allowing for the better placement of wells. The development of Formation Pressure While Drilling (FPWD) measurements has shown that formation pressure pretest information can be used to identify unintentional penetration of the impermeable zone. The more recent introduction of a Slim Hole Nuclear Magnetic Resonance While Drilling (NMRWD) tool and the development of an in-house methodology, allow for the characterization of the hydrocarbon components and prediction of the hydrocarbon viscosity.

The petrophysical integration of real-time formation pressure tests, mobility and viscosity information along with NMR fluid characterization are being used to optimally place and steer wells, to minimize contact with the immoveable hydrocarbon, to improve well injection performance and oil recovery