Enlightening Reservoir Fluid Distribution and Derisking Brown-Field Development with the Combination of Downhole and Surface Fluid Mapping Services

To perform downhole fluid analysis and/or downhole fluid sampling evaluation and acquisition, a fluid mapping/sampling-while-drilling tool (FMWD) is set stationary at a chosen depth. A probe/packer is sealed against the borehole wall, isolating the tool flowline from the wellbore, and connecting it to the reservoir. Then a pump, inside the tool, is triggered to perform a pump-out: formation fluid is displaced from the formation through the downhole tool and analyzed with various apparatus for in situ measuring. While some formation fluid might be captured in a sampling bottle, the fluid is largely expelled into the borehole. This entire operation is performed with drilling mud being circulated down the drill-string, through the bottomhole assembly (BHA), and up the annulus. During pump-out, mud circulation is required to drive the turbine within the FMWD tool, providing power to the FMWD tool and secondly, to enable the measurements-while-drilling (MWD) telemetry used to send sampling data to surface in real time and for downlink control of the FMWD tool. The pump-out process and the circulation continue until clean formation fluid with low mud filtrate contamination is observed by the downhole fluid analyzer. The operation may take up to several hours with the entire drill string and bottom-hole assembly (BHA), including the FMWD tool, stopped stationary at one specific depth without rotation. This represents a risky operation that can result in the BHA being stuck in the well bore temporarily, and at worst permanently lost in hole. Aggravating factors include (but are not limited to): wellbore instability, swelling clays presence, high angle wellbores, large overbalance, and static and dynamic drilling fluid losses. Typical mitigation consists of reducing stationary time. However, this cannot be achieved without sacrificing data quality and a representative fluid sample; especially since said stationary time is typically arbitrary limited to 60 or 90-minutes, irrespective of the acquisition objectives. Station staging has proven to be effective, to a certain extent, to mitigate the effects of short stationary time while still providing acceptable downhole fluid analysis or sample quality. The tool is set multiple times at the same depth, therefore continuing the clean out process over multiple stages (Villareal et al, 2010; Bravo et al, 2019; Zulkipli et al, 2023). Advanced mud gas (AMG) analysis and monitoring at surface offers a viable solution for mitigating the risks associated with the aforementioned challenges. AMG is concurrently run on the surface while circulation is ongoing. As pump-out progresses, formation fluid is released into the borehole and can be analyzed once at surface. This combination brings several possibilities: shorter fluid stations can be performed as the AMG requires minimal fluid volumes to perform the analysis, the service can be used as a backup in case the downhole sampling tool fails while analyzing the formation fluid and/or taking the downhole fluid samples, and data can be directly compared with data obtained while drilling to help optimize/refine subsequent pretesting and sampling zones. The AMG device analyzes the fluid expelled by the FMWD tool into the mud and recovered on surface providing downhole fluid composition-like measurements in the C1-C5 range, C6+, and gas-oil ratio (GOR) from an innovative machine learning algorithm.