Abstract
Using hydraulically fractured vertical wells (HFVW) to develop low permeability flank area with poor reservoir properties lead to suboptimal production. In 2022, Shell Oman successfully drilled, cemented, completed, and tested the first multi-stage fractured horizontal well (MSFHW) pilot. The MSFHW delivered 1045m lateral length in MMQ sandstone at TVD of 5000+m with 12 fractures in 10 stages. A companion HFVW with 630m offset from the MFHW was drilled and logged for formation property control. A 3D hydraulic fracturing model was built based on logs in both wells, which was calibrated using a variety of measurements, such as DFITs, sonic logs, RA tracer logs in offset wells. The calibrated model provided fracture geometries and conductivity to be used in modelling of horizontal pilot fracturing. These results enabled to develop a comprehensive plan to systematically design, execute, monitor, and verify the hydraulic fracturing operation for the pilot well. Specifically, fracture height in the vertical well with a small perforation interval is assumed very close to transverse fractures along the MSFHW. This allows designing fracture height evaluation program in the VW to assess transverse fracture heights of the MFHW, which is imperative for success of the horizontal pilot. Integrated hydraulic fracturing and reservoir dynamic simulations were also conducted. The modeling results helped optimize HW hydraulic fracturing, improve well performance, understand advantages and limitations of MSFHWs over HFVWs and better develop poorer areas.
The paper will also address some of the unconventional technologies applied in fracture fluid and placement. For the first time in Oman application of pump down plug and perf for deep tight HPHT well, use of natural sand/proppant to enhance fracture placement and optimization of placement design will be discussed. Well tests results from both VW and MSFHW confirmed the pre-frac design and expectation of the well performances.
