Document describes field specific challenges, proposed solutions, and results of a collaborative approach between Operating Company and Service Providers that led to increased longevity and reliability of downhole equipment deployed in high pressure and extreme sour field wells for recording production logging (PLT) data, along with project planning and execution process.
As logging tools durability is a crucial factor in obtaining high quality geophysical data and fulfilment with a planned work scope, Company's well mechanical intervention team initiated a joint project on enhancement of existing deploying PL tools and adopt them to current extreme downhole conditions.
The main goal of the project was to increase longevity one of the main PLT platform elements - Caged Flowmeter tool (CFM), which had a complicated mechanically rotating measurement system, driven by downhole fluid flows. The enhancement of the CFM tool aimed to fix the hardware issues, caused by mechanical impact of high flowing rates, and extend time of uninterrupted operations in wells with extreme harsh downhole conditions (sour, high pressure environment operated at extreme high flowrates).
The first step was to determine tool operational limitation factors and flaws in prior tool design. After revision of issues experienced in a past, a number of changes were recommended to be applied to tool design and maintenance procedures. Main changes were applied to rotating elements (i.e. type, material, installation concepts). The initially proposed solution did not provide the expected improvements and subsequent field operations revealed other hardware issues related to CFM spinner blockage by debris. Further analysis and discussions with vendors on issues revealed during operations helped to understand main concepts to be followed during the project execution. A decision was made to completely change the tool design, without compromising its integrity, i.e. keep housing and elastomer materials unchanged and H2S/CO2 resistant (Inconel 718 and FFKM elastomer).
Next step was to select bearings and spinner types from proposed options; and test developed new design tool in vendor's lab prior to field trial. Tool was exposed to high velocity air flow for duration at least 2 times the typical PLT logging duration in Kashagan.
After successfully performed lab tests, the most suitable bearing option was selected and finally proceed with 3 wells field trial and 5 more subsequent jobs during following period at real downhole conditions. At the end of the trial period, based on Company's Subsurface team and SME's feedbacks, concluded that the developed design proven it achieved the measurement specifications and design reliability.
As the result of nearly 2 years of work (one-year of study, following one-year trial and error period), detailed planning and collaboration between operating Company's departments, service provider and tool vendor, introduced the highly durable downhole flowrate measurement tool that can be widely used globally, in extremely sour and HP/HT well environments combined with extreme high flowrates.
