Abstract
Dubai Petroleum Establishment (DPE) has been developing a field offshore UAE using directional drilling and logging-while-drilling measurement services. Multiple horizontal wells are being drilled to develop this field, and due to the thickness and complexity of the target reservoir, the wells are being geosteered with deep-directional resistivity measurements to map the target boundaries. While successfully drilling these wells while remaining in the target, the previous generation of measurements did not enable mapping of the target top over the entire section. In 2023, a new deep- directional propagation resistivity tool was introduced to improve geosteering decision making while drilling horizontal development wells.
Although deep and ultradeep propagation resistivity measurements from various tool configurations have been used for geosteering and reservoir boundary mapping for several years, the resistivity inversion is challenged as reservoir complexity and distance to boundary increase. The new technology introduces deep, calibrated resistivity measurement from a tilted antenna at farther spacing than typical resistivity measurements. This provides the deeper depth of investigation required to map the top of the target in this formation. In addition, deterministic inversions have been applied to the measurements, in contrast to the Monte Carlo-type inversion used in previous generations of deep- directional resistivity measurements. Deterministic-based inversions have shown better resolution when deployed for ultradeep propagation resistivity tools that use a wider spectrum of measurement spacing and frequency but have not previously been used for deep-resistivity tools.
The introduction of this technology improved the depth of investigation for mapping reservoir boundaries in this field and target intervals by 80%, allowing for earlier and more efficient decision making, which resulted in a smoother wellbore with fewer undulations. The target formation drilled with this new technology has several thin, clinoform features, dipping at a high angle relative to the overall formation dip. Using the high-resolution multilayer inversion with these deeper measurements, these clinoform features could be mapped, providing a better overall understanding of the reservoir.
The introduction of enhanced deep resistivity measurements and a high-resolution inversion allowed for improved geosteering and reservoir understanding to develop this offshore field.
