Deepest relief well in history in HP/HT conditions

Overview

An operator in remote Asia suffered a kick during a wireline-fishing operation in a natural gas field. The operator was unable to control surface pressure, losing control of the well.

The target wellbore was 21,000 ft (~6500 m) TD with more than 20,000 psi bottom hole pressure (BHP) and 300°F (150°C) BHT. The formation contained multiple thick salt lenses, some as thick as 700 ft (~216 m). Formation integrity was also a concern because of the high pressure. The risk of early hydraulic communication was present due to the proximity of the target well to the relief well.

Challenges

To manage pressure during the well-kill process, the relief well had to communicate with the target well at a precise intercept window.

Results

All 20 pressure points requested by the operator were measured. The scope spanned the entire reservoir and its various phases and stratigraphic components. High-pressure and high-mobility zones were identified in the main reservoir body. Gradient analysis identified two phases, water and oil. The stratigraphic bodies above the main reservoir, which were targets in previous wells, had low pressure, mobility, and permeability values. These results correlate with those obtained from quad-combo data through a detailed petrophysics analysis.

Pressure test acquisition with LWD solution

Acquiring pressure test data with wireline would have been a technical challenge and added cost for the operator due to the high-angle well trajectory crossing the reservoir. Halliburton proposed a quad-combo package, including the GeoTap^® IDS service and iCruise^® intelligent rotary steering system (RSS),  to meet formation evaluation requirements and provide crucial information for reservoir development plans. As this was the first run with GeoTap® IDS service in the country, pre-job planning was vital for outstanding service delivery. Collaboration with the operator involved multiple meetings between the drilling, geology, and reservoir teams, and Halliburton to support directional drilling and logging feasibility. These meetings also covered BHA engineering, simulations, risk assessment, offset analysis, and formation test procedures.

A total of 20 pressure test points were acquired in a single run, addressing the operator’s requirements. The geology and reservoir teams received valuable information from the pressure test results, such as reservoir gradient and compartmentalization interpretation.

Drilled to target and executed pressure test plan

The team achieved a high directional drilling index (DDI) well trajectory to target total depth using a complex quad-combo BHA that included GeoTap^® IDS service and the iCruise^® intelligent RSS. They performed 20 pressure test points in a single run and acquired two pressure gradient zones without any HSE or SQ incidents.

Pressure test samples provided reservoir insight

Results from pressure tests allowed the operator to enhance the target reservoir understanding and make real-time decisions about current operations and subsequent completion plans.

Solution

The WellSpot™ active magnetic ranging system generates a distinct magnetic field on the target well, which is then detected by sensors. By analyzing the signature of the induced magnetic field, an optimal trajectory can be determined.

Active magnetic ranging in salt formations has historically been difficult because of high resistance that insulates the current and prevents it from leaving the well.

Overcoming challenges with engineering and careful planning

The interception posed challenges specific to the high-pressure/high-temperature (HP/HT) environment. However, this was carefully managed through precise time management, equipment selection, and ranging run planning. The wellbore contained hundreds of thin salt layers and multiple larger sections (~700-ft thick). Through close collaboration with the onsite geology team, the ranging engineers designed a per-run assembly to mitigate the salt’s negative effects. A ranging determination was made during every run using the WellSpot™ active magnetic ranging system. Halliburton deployed the Geo-Pilot® rotary steerable system in line with the intercept well plan, ensuring the team maintained the minimum distance from the target well as required by the operator, thereby preserving wellbore integrity until reaching the intercept window.

WellSpot completes the deepest relief well in history, overcomes 700 ft thick salt formation

Results

Working closely with the onsite geology team, relief well engineers planned each run to ensure problematic salt layers did not affect the results. Through careful planning with the operator, the relief well team overcame challenging wellbore conditions by making precise equipment selections. As a result, the relief well team successfully intercepted the deepest relief well in history on the first attempt.