Abstract
Abstract Horizontal well drilling traditionally helps to improve the oil recovery and avoid problems of premature gas/water breakthrough. In Bouri field, offshore Libya, the main concern of the operator was to establish an advanced method of controlling gas and water encroachment in a fractured carbonate reservoir characterized by high vertical permeability. This paper describes the first Inflow Control Device (ICD) installation for Mellitah Oil & Gas, and the first such application in Libya. It was an integral part of a well completion aimed at evenly distributing inflow in a horizontal well, and at limiting the negative effects after occurrence of expected gas breakthrough. Due to small clearances involved, the ICD deployment presented a significant operational challenge. Swelling-packers were used to compartmentalize the horizontal and build sections, allowing better drawdown control and eliminating cross-flow issues. The completion required re-thinking of the established acid-wash treatment procedures, ultimately improving the overall well clean-up. Integrated analysis methods using steady-state wellbore hydraulic and 3D dynamic simulators were performed to generate flow profiles and calculate ICD pressure drop along the horizontal section. The models were updated using results from logging-while-drilling (LWD) and with real-time modifications to the initial design. To verify the inflow profile along the length of the ICD completion, production logging (PLT) was conducted. The inflow profiles compared favorably with those predicted by the models. Introduction The Bouri field is part of Block NC-41 and is located N-NW from Libyan capital, Tripoli, 120 kilometers off the Mediterranean Sea coast (Figure 1). The field was discovered in 1970s, and has subsequently been developed with two platforms (DP3 and DP4) and 82 development wells. Since start-up, oil production has often been affected by high water cut (WCT) and gas-oil-ratio (GOR) due to coning and fingering phenomena through the extensive fracture network of this carbonate reservoir. These were not significantly reduced even after extended reach / horizontal well drilling, prompting the operator to seek new technical solutions to address this problem. Bouri field currently includes two horizontal wells (here referred as Well#1 and Well#2), drilled at the end of 2009, where ICD completion technology was implemented to reduce gas/water coning by evenly distributing reservoir inflow, and to limit the negative effects after occurrence of breakthrough. Shortly after completion, production logging was performed to determine the baseline oil / water / gas influx along the horizontal section of the wells. PLTs also provided measurement of the base Sigma-log for saturation monitoring. Initial PLT results show that almost all ICDs are contributing to production, and are performing per expectation. Fluid entry points are clearly defined (Figures 2 and 3) and correspond to ICD nozzle locations.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call