Multidimensional Reservoir Mapping Service to Characterize 3D Fault Model and Guide the Landing Operation with Advanced Ultra-Deep Azimuthal Resistivity Measurements in the Fault-Block Reservoir

Abstract The large energy demand pushes the exploitation targets towards the more and more complex reservoirs in Offshore China. The fault-block reservoir is a typical representative, especially with a complex fluid system. The uncertain fault and reservoir characteristics greatly affect the accuracy of the fault-block reservoir model, the landing and lateral placement of a horizontal well. However, conventional technology usually could not accurately map the detailed characteristics as requested, which will cause a low-resolution reservoir model and the risky well placement, or even a wrong landing position with a high engineering risk. Fortunately, multidimensional reservoir mapping service brings hopes to these challenging operations in this kind of reservoir. Advanced ultra-deep azimuthal resistivity (UDAR) measurements can be processed by two novel deterministic algorithms fitting for any reservoir complexity. The answer products include 1D longitudinal resistivity inversion along the wellbore and 2D transverse resistivity inversion perpendicular to the wellbore, with up to 30m detection range from the wellbore. Moreover, multiple 2D transverse slices can be interpolated into 3D volume to represent 3D formation characteristics. These products can be effectively QCed to characterize a full 3D context around the wellbore for a better reservoir steering and understanding the reservoir structure and fluid distribution up to 3D level. Without having to tradeoff between high resolution and large depth-of-detection, these multidimensional reservoir mapping details can update the 3D fault-block reservoir model to make informed decisions for an accurate landing operation with the less drilling risks. This multidimensional service was deployed in oilfield P to guide a horizontal well to be successfully landed into a fault-block reservoir after passing a normal fault, meanwhile mapping the fluid distribution. Within 60m corridor around the wellbore, 1D and 2D inversions clearly mapped up to 5 resistivity boundaries and 6 layers vertically. 3D reservoir volume could release the formation profile along any direction. The normal fault was characterized by a throw of 40m and a fault plane dip of 50-60deg. Wellbore approached the fault from the right side until passing it from shale1 to similar shale2 layer. The bottom-water reservoir was remotely confirmed and mapped to help quantitatively land the well at 0.5m below the reservoir top. Current oil column is about 10m and there is no lateral water breakthrough in this area, indicating the reservoir production potential. The successful landing and reservoir mapping results validated the effectiveness of this UDAR multidimensional reservoir mapping service to address these geological and engineering risks. With the ability of mapping in all directions, multidimensional reservoir mapping products carry reservoir details up to 3D level to characterize a full reservoir image and pave a promising road for efficiently exploiting more complex reservoirs.