Improvements in horizontal drilling methods offer higher production rates, increase overall recovery, and postpone the effects of water and gas coning in thin reservoirs.
In the Paleozoic Unayzah sandstones of central Saudi Arabia, the main reservoirs in the Permian are well understood, but the pre-Silurian section is more complex. Geological studies and thorough integration of all data, including wireline logs, electrical borehole imagery, and core, led geologists to some startling conclusions and significant discoveries about the sedimentary sequence. This article outlines the efforts required to decipher the depositional history of the oil-bearing sandstones and discusses the wider implications of this discovery.
The new MDT Modular Formation Dynamics Tester tool offers major innovation. Multiple uncontaminated fluid samples, fast and accurate pressure surveys, determination of permeability anisotropy, and even a mini-drillstem test on wireline are all within reach of the engineer today.