How Can Horizontal Wells Improve Productivity Compared to Fractured Vertical Wells in Tight Gas Fractured Formation for Glacial Depositional Environment? (abstract)

摘要

Block A in the Grand Erg of Algerian Sahara is a tight fractured wet gas formation for a glacial depositional environment which consists of numerous reservoir layers that are dispersed both vertically and laterally in a complex sand dispersal system. A typical well will encounter layers of sandstones,siltstones, and shale which have significant different values of permeability,porosity,and gas saturation. In these complex reservoir systems,the knowledge of how reservoir properties are distributed is very important to develop and produce the field. This paper fully analyses the conjoint effects of current geological understanding,engineering and financial costs,and technologies on block A,where many wells have been drilled including vertical wells,fractured vertical wells,and horizontal wells.The results show that horizontal wells are performing much better than fractured vertical wells and producing at rates greater 10 times than vertical wells. Field examples will be shown and discussed for different type of wells including the conjoint effects of current geological understanding,engineering and financial costs,and technologies on block A.