Stratigraphic and petrophysical characteristics of cored arab-D super-k intervals, Hawiyah area, Ghawar field, Saudi Arabia

Abstract

Super-permeability or super-k (as defined here), refers to confined intervals that have production or injection rates of at least 500 barrels of fluid/day/foot. Eight cored wells - four producers and four injectors - show super-k performance within the northern Hawiyah study area. One injector well had multiple super-k flow intervals. Super-k flow correlates with specific limestone, dolomite, or fractured intervals based on an analysis of core and flowmeter data. A thin, high-permeability unit sandwiched between low-permeability strata characterizes the sequential stratification of stratiform super-k flow units. Oolitic, mixed skeletal pelletoidal, foraminiferal, fragmented Cladocoropsis or Cladocoropsis lithofacies may make up the high-permeability conduits in limestones, and various mud-dominated facies form the tight enclosing layers. Sucrosic or vuggy fabrics characterize the highly permeable layers in dolomite-controlled intervals, and mosaic textures form the tight envelope. Production from stratiform dolomite is typically from one or more thin (generally less than six-inch thick) stringers some of which represent tempestite deposits. Super-k flow from fracture-controlled intervals has no correlation with either facies or dolomite textural boundaries. An unexpected result of this study was the discovery that not all super-k flow comes from high-permeability features such as fractures or zones of dolomitized leached Cladocoropsis. Instead, ordinary rock fabrics with normal permeability ranges (0.1 to 1 darcy) characterize most of the super-k intervals in six of the eight wells examined.