Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Using Advanced Technologies to Solve Complex Reservoir Challenges in Shedgum Field, Saudi Arabia: A Case Study
(1) Data & Consulting Services, Schlumberger, Al-Khobar, Saudi Arabia.
(2) Geoscience & Reservoir Engineering, Saudi Aramco, Dharhan, Saudi Arabia.
In order to meet world energy demand, wells have to be drilled in more challenging frontiers and within very thin reservoir beds. Conventional geosteering and LWD measurements face considerable challenges with chasing thin targets. However, geosteering into such thinner reservoirs has been successfully achieved through the application of next generation LWD measurements. Deep, directional resistivity (DDR) from the PeriScope LWD allows well placement to be optimized in real time by using the tool’s sensitivity to approaching bed boundaries and the ability to accurately map distance to such bed boundaries and formation dip. The PeriScope technology has proven its ability to unlock previously uneconomic targets in both clastic and carbonate reservoirs all over the world by providing for proactive well placement.
In Saudi Arabia, Aramco has made use of applying the PeriScope LWD and well placement services for its more challenging targets. In this paper a case study is outlined where 2 laterals were drilled into a carbonate reservoir, with and without PeriScope LWD. A comparison is made between results achieved drilling lateral 1, using PeriScope LWD and in lateral 2, drilling using a conventional LWD approach. In both cases the objectives of the well was to place the well 1 ft below the top of an anhydrite cap rock and also to keep the well away from possible water encroachment thereby improving total oil recovery.
Conventional geosteering relies on logs from offset wells and real time measurements. An assumption is made that the formation follows a layer-cake model, in which properties are assumed to be laterally continuous. This assumption is often invalid, as smaller scale variations in structure can also significantly impact on geosteering, especially in thinner targets and provides a considerable challenge for conventional geosteering. By using PeriScope these changes can be proactively managed in real time. In this case study lateral 1 was planned and drilled using PeriScope LWD in the BHA while Lateral 2 was later drilled with a conventional LWD BHA. Lateral 1 was placed in a porous stratum from target entry (TE) to total depth (TD) with no reservoir exit. Whereas 16.8 % borehole-to-reservoir exposure with formation greater than 0.15 porosity unit was achieved in the lateral drilled with conventional LWD. The results confirm the added value of proactive well placement through the use of the PeriScope LWD technology.