Vertical Permeability: Field Cases

Abstract

This paper compares the vertical permeability of several field cases, as obtained using different techniques. The vertical permeability of a reservoir is often of major importance: –where water or gas coning is likely to be a problem,–when pressure maintenance is carried out in multi-layer reservoirs,–in many reservoir simulation studies,–if horizontal wells are envisaged. The following methods were used to determine the vertical permeability: –well test analysis: partial penetration, multilayer and horizontal well tests in both conventional and fractured reservoirs,–coning analysis,–RFT vertical gradient and build-up analysis. A comparaison of the vertical permeability values obtained, using the various methods listed above, makes it possible to establish the interpretation consistency. A comparison with core measurements makes it possible to evaluate reservoir homogeneity. When vertical permeability is measured from cores it is generally higher in comparison to measurements obtained using dynamic methods. This is because core measurements do not allow for middle scale fluid barriers. Dynamic measurements of vertical permeability combined with statistical methods help determine the magnitude of fluid barriers causing permeability anisotropy in the reservoir. In fractured reservoirs, vertical permeability is often low as a result of discontinuity of the fractures at the bedding planes. Well tests and coning analysis are the best methods for determining vertical permeability and evaluating fracture continuity in the reservoir.

Simulation Study of a Naturally Fractured, Oil-Wet, Water Drive Reservoir

“…Th i s study was reported ina previ ous paper (2). Th i s study was reported ina previ ous paper (2).…”

“…The low vertical fracture permeability was also identified as a key factor in preventing water breakthrough (2). Recent results (8,9) provided evidence that low vertical fracture permeability and partial vertical conrnunicati on may often occur in naturally fractured reservoirs.…”

Vertical Interference Testing Method Using Dual Completions with Downhole Water Sink

“…[1][2][3][4] After the test, the bottom completion should often be cemented to prevent early water breakthrough into the well. However, in spite of the inconvenience and cost vertical interference tests should have better resolution and quality of the obtained results comparing to a single-well test.…”