No abstract

Multiphase flow metering (MPFM) technology is gaining popularity and becoming the main well rate testing mechanism in some regions of the world. Yet, their application in measuring the flow rates of high gas-oil-ratio (GOR) and/or high gas volume fraction (GVF) wells has always been a challenge. A remote field located in the Southeastern part of Saudi Arabia commenced its production in the late 90's from a thin oil column lying between a large gas-cap and a water aquifer. Although, 84% of the thin-oil-column producing wells are horizontal and multilateral wells with extended reservoir contact, the gas-cap gas breakthrough and production from these wells have increased gradually; resulting in an increase in the wells GOR.Currently, 35% of the wells are producing at high GOR ranging between 2,000 and 6,000 SCF/STB with a GVF reaching as high as 98%.

Successful reservoir surveillance is a key component to effectively manage any field production strategy. For open hole extended reach horizontal wells, including some wells over 30,000 ft in length, the challenges to successfully deploy real-time logging tools are greatly magnified. This is further complicated by constraints in the completion where Electrical Submersible Pumps (ESP's) are installed. A comparative review of the latest technologies and methods available to overcome these challenges will be explored. The challenges are formidable and extensive; logging these extreme lengths in cased hole would be difficult enough, but are considerably exaggerated in the open-hole condition. The logging run in open hole must also contend with increased frictional forces, high dogleg severity, washouts and an increased well bore rugosity. The main challenges to achieve the logging objectives in open hole extended reach wells, are 2-fold, namely; To log the entire open hole section and reach the Total Depth (TD) of the well. To obtain high quality data from the logging tools, despite the adverse downhole environment. To achieve these 2 main objectives, a comprehensive approach is taken while designing the logging operation. The choices available to deploy the logging tools are mainly on electric-line cable with an electric powered tractor or on coil tubing with a hydraulically powered tractor. The most common type of log performed in these extended reach wells is a production log to measure multi-phase inflow contributions. To improve the success rate of the logs, a number of initiatives have been implemented, including deployment of custom designed coil tubing tractors and state of the art wireline tractors. The logging tools and job programs are adapted based on the results of simulations, accounting for many variables, including the completion, well type, deviation and target depth. The ability to successfully log these extended reach wells cannot be understated, reservoir simulations and management decisions can only as good as the quality of data available. Some of the advantages of drilling mega reach wells such as increased reservoir contact, reduced footprint and less wells drilled will be lost if adequate reservoir surveillance cannot be achieved. To meet the key objectives, creative solutions including designing and upgrading the best fit for purpose technologies are applied for the extended reach wells. These steps taken not only improve the overall logging performance, they can also result in cost savings by avoiding multiple unsuccessful logging runs.

This paper discusses an innovative reservoir diagnostic solution for oil wells using a hybrid plug-n-play platform conveyed via coiled tubing (CT). It further highlights the unique characteristics of this system, delving into the first field operations for a major customer. This step-change telemetry and data collection technology will now give operators comprehensive reservoir understanding, shrinking their learning curve for completion optimization, and further enabling customized solutions by featuring a single-trip concept with minimal equipment requirements. Existing solutions for real-time CT operations normally rely on electrical-conductors, fiber-optics, or mud-pulse telemetry. Each one of these options has its pros and cons, but none of them can satisfy all critical operational needs simultaneously. Fiber-optics-based systems do not allow continuous power supply. Conductor-based systems cannot support the continuously emerging "distributed" sensing services based on optical reflectometry. Mud-pulse telemetry systems have limited data bandwidth while requiring continuous circulation. A hybrid optical/electrical platform represents a significant evolution in CT telemetry. Based on combined optical/electrical communication, this "single-trip" intervention concept provides complementary diagnostic services while delivering regular CT intervention work. A successful multi-well campaign of real-time production logging was performed with a major customer in the Middle East. A hydrocarbon flow profile was identified across an extended-reach, horizontal, oil-bearing, open-hole section. The hybrid optical/electrical platform enabled all required conventional remedial well interventions before or after the main log. Prior operations with conventional e-line CT imposed severe limitations in terms of complementary services that could be delivered as part of the same campaign: wellbore cleanout, nitrogen lifting, acid pumping, etc. Use of the novel hybrid electric and fiber-optic platform with the full support of real-time production logging enabled a successful execution of this campaign. With its negligible outer diameter, and chemical and abrasion-resistant encapsulation, the hybrid cable does not affect the normal operating envelop of CT operations. The downhole assembly features a flow-through sensor module that can be used independently or simultaneously with wireline adapters for real-time production logging and more. The sensor module provides critical information to ensure operations are performed under the best conditions, including a casing collar locator, gamma ray to correlate, weight on bit and torque to protect the logging tools in case of restrictions, pressure, temperature, tool face, and vibrations. A flow-through camera can also be included into the string for further insight. The introduction of the new hybrid fiber optic and electric conductor platform represents the next technological evolution in well intervention. It increases equipment reliability and efficiency and, more importantly, enhances real-time monitoring and diagnostic capabilities to better achieve customer objectives. Notoriously complicated operations, like multilateral well re-entries and downhole tool manipulations, can now also be optimized and will benefit from the newly introduced system.

Successful reservoir surveillance and production monitoring is a key component for effectively managing any field production strategy. For production logging in openhole horizontal extended reach wells (ERWs), the challenges are formidable and extensive; logging these extreme lengths in a cased hole would be difficult enough, but are considerably exaggerated in the openhole condition. A coiled tubing (CT) logging run in open hole must also contend with increased frictional forces, high dogleg severity, a quicker onset of helical buckling and early lockup. The challenge to effectively log these ERWs is further complicated by constraints in the completion where electrical submersible pumps (ESPs) are installed including a 2.4" bypass section. Although hydraulically powered coiled tubing tractors already existed, a slim CT tractor with real-time logging capabilities was not available in the market. In partnership with a specialist CT tractor manufacturer, a slim logging CT tractor was designed and built to meet the exceptional demands to pull the CT to target depth. The tractor is 100% hydraulically powered, with no electrical power allowing for uninterrupted logging during tractoring. The tractor is powered by the differential pressure from the bore of the CT to the wellbore, and is operated by a pre-set pump rate from surface. Developed to improve the low coverage in open hole ERW logging jobs, the tractor underwent extensive factory testing before being deployed to the field. The tractor was rigged up on location with the production logging tool and ran in hole. Once the coil tubing locked up, the tractor was activated and pulled the coil to cover over 90% of the open hole section delivering a pulling force of up to 3,200 lb. Real-time production logging was conducted simultaneously with the tractor activated, flowing and shut-in passes were completed to successfully capture the zonal inflow profile. Real-time logging with the tractor is logistically efficient and allows instantaneous decision making to repeat passes for improved data quality. The new slim logging tractor is the world's slimmest most compact, and the first of its kind CT tractor that enables production logging operations in horizontal extended reach open hole wells. The ability to successfully log these extended reach wells cannot be understated, reservoir simulations and management decisions can only as good as the quality of data available. Some of the advantages of drilling extended reach wells such as increased reservoir contact, reduced footprint and less wells drilled will be lost if sufficient reservoir surveillance cannot be achieved. To maximize the benefits of ERWs, creative solutions and innovative designs must continually be developed to push the boundaries further.