High Performance Low-Invasion Fluids Technology Enhances, Optimizes Drilling Efficiency in the Gulf of Suez – Egypt
Objectives / Scope: The main objective of this paper is to characterize the drilled shale formation in order to select and propose a "tailored" High Performance Low Invasion Fluids (HPLIF) system aided by Bridging Particles Optimization Tool (BPOT)(5),(6)(9)(11), capable of maximize hole stability in pressure depleted sands, allowing optimized well design through reactive and dispersible shale formations(7)(8) that eliminated one casing section, and to replace Oil Base Mud (OBM) and avoid its HSE issues related to use it, consequently, reduce formation damage, eliminate waste management cost, minimizing Non Productive Time (NPT) and finally enhances Drilling performance.
Methods, Procedures, Process: This paper explain the reactivity information about Shale Samples recovered from different wells drilled in the-GOS-Egypt followed by extensive laboratory testing done(1) in order to characterize the main clay minerals presented in the samples using X-Ray Diffraction-(XRD) technology and their meso-and micro-structure by Scanning-Electron-Microscope-(SEM) and their reactivity to compare the inhibition efficiency of the proposed-(HPLIF)-System with Blank and Conventional Water-Base-Fluid-System. The reactivity of the cuttings was assessed by Dispersion, Swelling and Hardness tests. Field application experienced (HPLIF) System combined with Well-Bore Strengthening Materials (WSM) gives the required protection against induced losses and reducing the risk of differential sticking problems when mud overbalance is above 2500 psi(5), (6)(9)(11).
Results, Observations, Conclusions: Compared with the use of conventional fluid systems, Field data demonstrated the successful application of (HPLIF) System combined with (WSM) and shows a great success during drilling through reactive clays, dispersive shale, naturally micro fractured(8), and depleted sand formations in many wells drilled in the GOS(2), (3), (4). Drilling operations reported no differential sticking, or wellbore instability issues even at highly mud overbalance or at highly deviated wells. The first challenged well R1-63 was drilled about 2391 ft, through 8.5" hole using 9.8-10.01 ppg using (HPLIF) system, penetrating through Thebes, Esna Shale, Sudr, Brown Lime Stone, Matulla, Nubia"A" Sand and Nubia "B" without any down-hole losses. Additionally, there was no sticking tendency experienced during drilling or while recording pressure points. The Non Productive Time NPT showed a reduction by about 19.2%. Finally, it ran and was cemented the "7" Liner in open hole successfully without problem. For the second challenged case well # 2, the Open hole was exposed to (HPLIF) water based mud system for a long period of time while rig repairing, rig switching, and during drilling operation. The well had 6" hole from 12,752 To/14,945 (2193.0ft) through Red bed, Thebes Esna, Sudr, Matulla and Nubia Sand formations with max inclination 68.6° and bottom hole temperature 325°F using 10.0-10.5 ppg (HPLIF) system, the 4.5"liner successfully was ran, cemented without any problems. The-HPLIF-System has also been shown to give excellent wellbore stability in brittle shales Fm where bedding planes or micro-fractures can become pressurized with mud, leading to wellbore instability. This innovation avoids induced lost circulation and differential sticking when the mud overbalance is expected to be greater than ±2500 psi. Additionally, the proposed solution enhances the drilling operation, reduces the waste management costs, eliminates a possible additional casing string, and finally minimizes the (NPT) which reflects on the overall cost of drilling these challenged wells.
