Successful Implementation of Engineered Fiber Based Loss Circulation Control Solution to Effectively Cure Losses While Drilling, Cementing and Work Over Operations in Oman

Abstract

Oman is a hotspot for drilling activity and wells are being drilled in different environments varying from Deep exploration and development for gas and oil and water injection/disposal. One challenge tops all other challenges: Lost Circulation. Due to the fractured/fissured nature of the formation and low existing reservoir pressures, all major operators are suffering from lost circulation challenges. Some of the challenges include: Mud losses while drilling leading to cost overruns and HSE concerns, primary cement job failure due to not getting the cement up to the desired height resulting in subsequent sustained casing pressure and corrosion, not able to perform work over activity on certain wells due to losses. Enormous quantities of water are required to maintain well control, and due to the limitation of water availability all over Oman, this becomes another critical issue. An Engineered fiber-based Loss Circulation pill has proved successful to address these challenges in multiple fields for Petroleum Development Oman. Drilling shallow wells in Oman through the naturally fractured limestone formation of Natih, usually results in significant losses of up to 55 m3/h (346 bbl/h) even with a low density drilling fluid of 1,033 to 1,070kg/m3 (8.6 to 8.9lbm/gal). Packoffs are often observed due to the swelling shale section, which leads to several attempts with kick-off plugs and sidetracking. Engineered fibers pills enabled total returns to surface when no other loss circulation solution had worked before. This also enabled to bring cement all the way to surface using 1,410kg/m3 (11.8lbm/gal). In another field, a work over rig was mobilized to perform a well kill operation and pullout. Due to total losses through perforations into the reservoir, the well kill could not be completed. In addition, every time the water level fell gas started to flow in the well. After 17 attempts and 8 loss circulation material pills, a total of 763m3 (4,800bbl) of well-supply water had been pumped. An engineered fiber pill at 1,474kg/m3 (12.3lbm/gal) was designed and bullheaded into the perforations. The pressures while pumping and squeezing rose to 11,031kPa (1,600psi). The well was shut and observed for 3 hours without any pressure increase indicating losses were cured and gas flow stopped. Engineered fibers have proved their value in all sorts of lost circulation applications in North Oman. These pills have been successfully used to mitigate losses while drilling, while cementing, during mud circulation before cement job when the casing is on bottom and in work over jobs in depleted reservoirs. With the level of success achieved with such treatments, in some fields it has become a standard practice for curing losses.

A Novel Solution for Severe Loss Prevention While Drilling Deep Wells

“…The most common method is using solid particles, which are referred to as lost circulation materials (LCMs) to reduce and prevent any loss of circulation. The common LCMs include flaky, granular, fibrous, blended, water/acid-soluble, hydratable/swellable LCMs, nanoparticles, cement plug, polyurethane grouting, settable plugs, crosslinked gel, and viscoelastic surfactant [9][10][11][12].…”

Risk Planning and Mitigation in Oil Well Fields

“…Engineered fiber-based loss circulation control pills, based on a specially engineered fiber system and the particle size distribution principle, were used successfully in Oman, Northern Pakistan and the Republic of Congo (Jain et al 2013;Arshad et al, 2014;Gupta et al, 2015). The pills use synergy between the physical characteristics of fibers and solids to plug fractures that can cause partial or total circulation losses during drilling or cementing operations.…”

“…Engineered fiber-based loss circulation control pills was successfully used to combat severe loss circulation challenges during drilling and casing cementing in Oman and Northern Pakistan (Jain et al 2013;Arshad et al, 2014). The pills were robust enough to work in water-based mud (WBM), oil-base mud (OBM), or synthetic-based mud (SBM) environments with weights up to 2040 kg/m 3 (17.0 lb/gal) (Arshad et al, 2014).…”

Mechanical Properties of Eichhornia Crassipes Fiber as Lost Circulation Material for Oil and Gas Drilling Application

“…Ideally, they have the ability to form bridge-like networks in front of the fracture zones. mud cakes that filter drilling mud flow to the fractured formation and thereafter completely shut off the lost zones [12].…”