--> Characterization of Fluid Composition While Drilling to Aid Horizontal Well Placement in an Oil Rim Reservoir presented by Marcus Turner

2018 AAPG International Conference and Exhibition

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Characterization of Fluid Composition While Drilling to Aid Horizontal Well Placement in an Oil Rim Reservoir presented by Marcus Turner

Abstract

A wide range of technologies and workflows are available in real time to assist in optimizing the horizontal drilling process and provide thorough formation evaluation analysis while landing and steering horizontal wells. Traditionally, Advanced Surface Fluid Logging (ASFL) has not been relied upon as one of these methods, however the real-time fluid analysis provided by this technology, was utilised to achieve a better understanding of fluid distribution while supporting critical decisions whilst landing the horizontal section. Understanding the fluid complexity in the Danish North Sea chalk field was the main key in optimising the placement of the well. Initially, it was predicted that due to migration of the gas cap, the fluids in the oil rim target would have undergone significant compositional change from the virgin fluid. Placement of the well at the top of the expected oil column was critical in order to intercept as much of oil as possible, whilst mitigating against premature water/gas breakthrough and ensuring a minimum standoff from the Gas Oil Contact (GOC) was maintained. To optimize this recovery, it was decided to integrate for the first time globally and in real-time, ASFL with conventional Logging While Drilling (LWD) measurements. A gradual compositional variation from heavy to light oil was recorded whilst building the inclination to the landing point of the well. The changes from fluid 1e (orange), through 1b (blue), to 1d (red) are considered to be indicators of a moving GOC. The AGM technique allowed in real time accurate and immediate identification of subtle compositional changes during the landing section throughout the horizontal section. Oil was identified as the fluid in place at the point of landing, with six fluid facies identified throughout the reservoir section. The integration of the petrophysical analysis with the ASFL service during drilling of the horizontal section provided a better understanding of the fluid distribution in the reservoir whilst ensuring the wellbore did not exit it.