IntelliServ WDP has been installed on a jackup rig in Martin Linge field, which is situated in the Norwegian sector of the North Sea. This field was discovered initially in 1975, but proved too complex to develop at the time.
Martin Linge resources consist of a shallow oil reservoir and several, deeper, structurally complex, HP gas and condensate reservoirs. The oil reservoirs are being developed with long horizontal wells, as well as several deviated wells being drilled to unlock the gas and condensate reserves. Several exploration and appraisal wells were drilled within a narrow pressure window, with multiple BHA runs per section. This complex drilling environment posed many challenges, including severe losses, influxes, unstable formations and excessive downhole shock and vibrations, resulting in poor MWD/LWD signals. To drill the wells within this complex environment more effectively, the WDP system was deployed.
IntelliServ WDP enables wells to be drilled without the typical limitations imposed by conventional telemetry methods, and also allows for improved decision-making in real time.
THE INTELLISERV NETWORK
The high-speed telemetry allows full utilization of available downhole data, providing real-time, memory-quality MWD/LWD data at surface and enabling optimization of the overall drilling process in real time.
The WDP system creates a high-speed data network that enables real-time, bi-directional data transmission at speeds of up to 57,600 bps.
There are five main components to the network (Fig. 1), which include:
- the NetCon, which creates and manages the drill string network at the surface;
- the Top Drive DataSwivel, which extracts the data from the rotating drillstring at surface;
- the wired drillstring components, which convey the signal along the string;
- the DataLinks, which boost and allow for diagnostics (health of the system);
- the interface sub between the MWD tools and WDP.
In addition, Along String Measurements (ASMs) were added to the drillstring, to provide real-time data along the string, such as pressure and temperature.
IMPLEMENTATION OF WDP
The WDP telemetry was utilized primarily during drilling of the last two sections of the wells (12¼-in. × 14¾-in. and 8½-in. × 9-in. sections) in the Martin Linge field development. The high-speed telemetry provided by WDP enables nearly instantaneous communication and control of downhole tools, and provides high-density, real-time data to enable rapid detection and reaction to drilling dysfunctions and other changes in drilling conditions. In case of network outage, drilling was continued, using the backup mud-pulse telemetry (MPT) system.
A number of application-specific capabilities were enabled by the WDP network, such as:
- Drilling entire sections without using conventional down links. No need for bypassing mud flow on surface while downlinking, especially when using MPD;
- Good-quality data from MWD directional survey sensors just after connections, avoiding the need to retake surveys;
- Round trips during MWD/LWD tool failures were avoided, as LWD tool diagnostics were run while drilling, enabling the operator to decide, in real time, whether or not drilling could commence without this specific, failed LWD tool, saving a round trip;
- Producing memory logs twice a day while drilling;
- Real-time recorded ASM data, even with the mud pumps off;
- ASMs delivering data during critical events, such as stuck pipe and downhole losses, as well as mud weight confirmation and behavior without an MWD in the hole;
- ASM data, used in combination with MPD, to monitor ECDs behind the BHA, and close to the shoe, to optimize use of the technology and ECD limits, which, in turn, lead to drilling increasingly longer reservoir sections;
- Instantly receiving the formation pressure results at surface, also in combination with dynamic FITs performed via MPD;
- Reduction of hole cleaning circulation time, based on ECD data measured along the string;
- Enhanced real-time drilling optimization, with early detection of drilling dysfunctions, such as stick-slip and high vibration levels, resulting in increased drilling performance;
- First-time application of activating dual reamers (main and near bit) with WDP. No need for an additional trip to open up the rat hole;
- First-time application of transmitting memory seismic data, enabling logging formation data ahead of the bit.
The high-speed telemetry provided by WDP enables wells to be drilled without the typical limitations imposed by conventional telemetry methods. The resulting efficiency gains and quantified time-savings of the wells drilled with WDP telemetry, when compared to the offset wells drilled with a conventional telemetry system, will be presented hereunder.
While using the WDP system, the telemetry time was analyzed and compared with wells that were drilled with MPT vs. the wells drilled with WDP telemetry.
After reviewing the data, a 72% reduction in telemetry time was found for the wells drilled with WDP. Some of the wells that were observed included sidetrack drilling and, therefore, drilled further, so the telemetry times found needed to be normalized. After normalization, it was clear that there was an 82% reduction in normalized telemetry time for the wells drilled with WDP, potentially saving >1 day per full well.
Another item studied during drilling of the wells was the WDP network maintenance. The network required some regular system checks, to maintain the health of the network, and to remove any components that might lead to an eventual network interruption.
The main causes for the telemetry-related NPT at the beginning stages of deploying the WDP were due to mechanical deformation of the box-end connection, as a result of surface make-up equipment that was not calibrated properly.
There was a strong decrease in NPT observed after the aforementioned issue was resolved, and rig personnel became more familiar with the technology. Overall, the WDP telemetry network was reliable, with an average uptime of 93%. The remaining 7% of drilling was performed with a backup MPT system.
As previously stated, the WDP network was utilized primarily to drill the last two sections of the wells (12¼-in. × 14¾-in. and 8½-in. × 9-in. sections). Drilling of the 12¼-in. × 14¾-in. section was controlled, due to complex downhole pressure regimes (below the 20-in. shoe), and in the reservoir section, due to the fragile nature of the sandstone and hole cleaning challenges, typically experienced in long horizontal sections. The WDP network was utilized most actively during drilling of the reservoir section. Full geosteering and RSS services were used to drill the drain sections and the real-time data were used to optimize the well path and reservoir exposure.
The drilling performance while drilling the reservoir sections with WDP telemetry was good, and it improved continuously, as experience was gained on how to optimize the drilling parameters and drill the section efficiently.
INTRODUCING NEW TECHNOLOGY
While the WDP system saved telemetry time and improved drilling performance, two downhole LWD tools still required further engineering, as these tools required MPT for their communication, even with the WDP network up and running. A subsequent software upgrade was required and installed for each of these tools, to remove the pressure fluctuations from the mud pulses and further maximize the utilization of these tools on WDP.
These two technologies, which communicated for the first time through WDP telemetry, were a dual integrated reamer and a seismic-while-drilling tool.
The high-speed WDP telemetry network enabled integrated on-command reamer activation and deactivation, without reliance on mud pulse, which allowed real-time monitoring and control from the surface, Fig. 2. The integrated dual reamer activation via WDP, the world’s first, saved valuable rig time. With WDP telemetry, each reamer command is sent and received instantaneously, saving 3 min. per command, when compared to MPT.
It is estimated that the on-command reamer activation saved the rig 6 min. per activation/deactivation, for a total of four hours saved. The on-command, near-bit reamer activation and confirmation also eliminated the need for a dedicated rat hole clean-out trip, saving one rig day per section.
The seismic memory quality data were transmitted through the WDP network in real time to surface, which enabled ‘looking’ 200 m in TVD below the bit, Fig. 3.
The seismic-while-drilling tool detected relevant formations 200 m, TVD, below the tool in real time. This was achieved by sending first break data with reflective data, real time, through the WDP. Further development of the internal tool software will increase this distance in TVD.
The use of the seismic-while-drilling tool, in combination with the extra-deep azimuthal resistivity on WDP, enabled the next step in geosteering. The wells were navigated within the reservoir, with real-time memory quality formation evaluation and drilling dynamics data. This resulted in improved wellbore placement and increased reservoir section length.
- Valuable rig time savings through telemetry time savings, adding up to ~ 1 day/well;
- Good and steady drilling performance in the reservoir sections, achieved with WDP telemetry, and ROP continuously improved;
- The WDP telemetry network was found reliable, with an average uptime of 93%;
- Network maintenance time was tracked and decreased steadily throughout the project, to ~ 4.8 hr/well;
- New technology was developed and implemented successfully during the project, saving rig time;
- Geosteering was optimized with real-time memory quality formation evaluation and drilling dynamics data, which resulted in improved wellbore placement, increased reservoir section length (~1,000 m) and optimized sand exposure, from an average expected value of 67% to 81%;
- ASM readings proved valuable for understanding and management of ECD, when drilling the horizontal drains.
The actual, quantified time-savings that were achieved were greater than the operator initially expected, and have offset the additional cost for the WDP string, and associated running costs for using the high-speed telemetry system. Figure 4 shows the total costs vs. realized rig time savings during the first year of operations on Martin Linge, clearly demonstrating that the well time reductions were worth more than the cost of WDP.
The investment required for WDP is offset by the time savings enabled by utilizing high-speed telemetry. There was a set CAPEX for this project, for the purchase of WDP and other components. With telemetry time savings of 9.25 rig days minus the cost of WDP, this project delivered 4.25 rig days of net savings to the operator. These savings justified the upfront cost of investing in WDP, allowed for improved well placement and had a positive effect on the quality of the drains drilled.
To date, WDP has been used to drill six of the 11 planned wells on Martin Linge. The operator has been able to reduce the total wells from 11 to 10, due to better well placement with longer drains, and is drilling these initial wells faster than expected.
For more information on how WDP was used on Martin Linge to increase drilling efficiency and reduce well times, see SPE paper 178863.
by : Brian Van Burkleo, Reina Teelken, NOV