First Field Worldwide Trial: Advanced Coring System, A Disruptive Technology Applied in Abu Dhabi, UAE. To Provide Real-Time Logging while Coring, Saving Rig Time and Opening a New Era in this Operation
Authors: Nunez Ygnacio , Al Nuaimi Mouza Ali , Adene Olawole , Al Hammadi Aref , Ruiz Fernando , Al Hamlawi Imad , Escorcia Alvaro , Baptista Luis , Labbassen Nabila , Radovanovic Anna , Berger Per Erik , Mätzel Arne 
Published: May 2023

The search for oil dates to the 1850s, and, since continuous overtime improvements and enhancements to the available technologies have been introduced. However, the quest for continuous improvements is directly related to the advantages and ease of exploitation of this nature given resource. Currently, concepts of formation evaluation, which is the analysis of subsurface formation characteristics, such as lithology, porosity, permeability, and saturation, are acquired by methods such as wireline well logging, real-time logging while drilling and core analysis. The advantage of core analysis (coring) fully leans on the ability to retrieve cores as close as possible to the actual reservoir's properties, hence porosity and permeability can be more precisely evaluated. The main aim of this project is to prove that it is possible to core and log at the same time, thus saving time and increasing the accuracy of the coring points.

First phase of this trial as technological innovation is an Advanced Coring System (ACS), which cuts the core while logging, and contemplates gamma ray and resistivity sensors within the core Bottom Hole Assembly (BHA) itself, close to the core head.

Due to the presence of electronic components within the coring equipment, the core diameter was limited to a 3 in. OD core.

The first trial was done on a middle east onshore field during Q3 of 2022. The main objective was to ensure that reservoir information (gamma ray, inclination, vibration, temperature) was being acquired real time while using the Intelligent Coring System (ICS) to enable retrieval and interpretation of downhole data. The coring BHA was composed by a coring head, the Logging While Coring (LWC) tool, wired outer barrels, wired spacers and stabilizers, a drop ball sub, and an MWD module.

The coring assembly was successful at cutting and recovering the target core interval with good performance, comparable to standard coring BHA, however, the main objective of the trial, the LWC was not achieved. The MWD experienced malfunctions, hence no real-time gamma ray data was transmitted to surface. After POOH the assembly was laid down, and preliminary investigation at the rig site showed the showed fluid invasion of the electronics components, impairing the memory data retrieval. As a last resort, the memory board was disassembled and taken to the manufacturer's laboratory to attempt data recovery. Unfortunately, the board was damaged beyond repair due to the fluid ingress and the memory data was unretrievable.

The ICS is a novel technology, potentially disruptive of the way coring is done today: A coring system, which combines coring and real-time formation evaluation. A second innovative technology is under development, is the Downhole Convertible Drill Bit a system that allows downhole conversion between coring and drilling modes, thus saving several round trips. This system is to be tested in field applications.