Abstract

Advanced multilateral well drilling & completion requires the application of innovative technologies while drilling to place the well in sweet spots by managing all the geological uncertainties. The smart level-4 multilateral well with dual stacked lateral was drilled by integrating advanced Real-Time geo-steering formation characterization along with geochemical, advanced gas analysis and seismic data interpretation.The Burgan reservoir consists of vertically stacked channelsands associated with geological heterogeneities along with series of fault networks connected to the aquifer at the bottom. The reservoir contains ultra-high water mobility with down hole oil viscosity of about 40cp enhances water breakthrough and requires customized ICD and ICV completions to enhance dry oil production and maximize oil recovery. Real-time geo-steering performed on Multi-lateral well by utilizing advanced technologies including High resolution Geochemical Analysis has been utilized in Real-Time to identify "geochemical proxies" and allow geochemical steering, distance to boundary tool using 4 resistivity curves with deep spacing Geosignal, At-bit measurements and density image to correct well positioning and locating faulted areas.

The pre job planning had two components such as: (i) building a geosteering model based on offset well logs, geological and geophysical information and (ii) preparation of geochemical model based on XRF analysis of core chips from offset wells. The later model was calibrated through logs and utilized further to predict key rock attributes such as: (a) detailed lithological variations generally beyond the resolution of LWD logs, (b) detailed mineralogy to determine the diagenetic overprint and (c) depositional environment of different Burgan sand facies. Continuous interpretation and integration of XRF and petrophysical analysis supported by LWD data was a key factor for real-time geosteering operation.

Such integrated approach also resulted in successful placing the wells with maximum reservoir contact and also was very instrumental for (i) isolation of potential trouble zones, (ii) segmentation of horizontal sections and (iii) optimization of nozzle sizes of the ICDs and hence planning of smart completion designs.

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