Optimizing Petrophysical Analysis Through Logging Conveyance System Selection: A Wireline vs LWD Performance Evaluation
Authors: Alsinan Y. M. , Almogbel N. K. , Aldohailan M. A. , Manuaba I. B. G. H. 
Published: February 2025

Petrophysical analysis is crucial for planning field development, where accurate data acquisition is employed in designing the optimal strategy. Different logging conveyances can influence the accuracy of the acquired data. Hence, this paper presents a comparative performance analysis of the Wireline (WL) and Logging-While-Drilling (LWD) conveyances regarding data quality and representativeness by analyzing authentic data from existing wells logged using both methods. Consequently, the paper aims to optimize petrophysical analysis through fit-for-purpose logging conveyance selection.

To assess the impact of both conveyances, WL and LWD logs were run and analyzed across multiple wells. The comprehensive array of logs includes caliper, neutron, density, resistivity, formation testing (FTS), and micro-resistivity images deployed across different environments, formations, and a range of resistivity values. The analysis also explores deploying LWD across sections drilled with varying rates of penetration (ROP) resulting in different degrees of mud invasion, in addition to different hole size sections, namely 8.5" and 6.125". The evaluation conducted assesses data accuracy and representativeness, offering insights into the strengths and limitations of both conveyances.

The collected data demonstrated considerable differences among the two conveyances, showcasing their respective strengths that can prove to be more favorable in different cases, depending on the specific well objective. There are several factors that possibly affected the downhole measurements, yielding different results and log responses. One of which is the distinct tool designs tailored for diverse environments in each conveyance, affecting the precision of data and measurement responses. Another element that was observed to have an impact on the data is the borehole condition during logging. WL tools are designed taking mud invasion into consideration, allowing for logging in static conditions and accounting for exposure time effects. On the other hand, LWD is deployed in dynamic conditions, and requires invasion correction during data analysis. Furthermore, the timing of data collection plays a significant role in affecting measurements, as it occurs after varying periods for each conveyance. Other factors include logging speed and tool position, which could influence the results due to differences in acquired data density, tool characterization and standoff.

The comparative analysis concludes that WL and LWD conveyances should be tailored to well objective to produce representative data. This is especially important in exploration and evaluation wells that will determine delineation and development plans, reservoir sweep analysis, and future well placement. The data analysis presented in the paper show the effects of conveyance on the acquired data used in petrophysical analysis and formation evaluation considering a range of reservoir parameters, hole sizes, and ROPs.