Multiphase Flow in Unconventional Liquid Rich Shale Oil Reservoir

Multiphase Flow in Unconventional Liquid Rich Shale Oil Reservoir

Richard Cao

Objectives/Scope:

The objective of this paper is to study the complex multiphase flow recovery process in unconventional Liquid Rich Shale oil reservoir with extremely low permeability, especially the unusual high Water Oil
Ratio observed in the unconventional horizontal wells at Permian Basin, where one barrel of oil production usually comes with 2 to 4 barrels of water for the Avalon, Bone Spring, and Wolfcamp formations.

Methods, Procedures, Process:

Numerical modeling, field pilot test, and production trend analysis are integrated to understand the oil, water, and gas recovery process in the unconventional Liquid Rich Shale oil reservoir at Permian.
The numerical model was divided into three zones, matrix, hydraulic fracture, and SRV (Stimulated Rock Volume). Different rock, fluid, and relative permeability properties are implemented in these zones. A vertical pilot well was drilled with isolated production from different stratigraphic layers with different rock fluid properties to test the relationship of water cut with subsurface parameters. The fractional flow from the pilot is compared with the numerical results.

Results, Observations, Conclusions:

Statically History Match is performed to obtain good history matching of oil, gas, and water from the actual production. The unusual behavior of high water oil ratio in the Permian LRS horizontal wells is explained with fractional flow from the matrix and fracture, as shown in attached Figure 1. It is found that the water in the Liquid Rich Shale can flow despite the extremely low nanoDarcy
permeability. The water from the matrix forms the base of the produced water, enhanced by other subsurface geological features such as wet sand layers, high perm non-net
pay zones, and natural fractures. At the same time, the hydraulic fracturing process plays a very important role in determine the oil/water/gas recovery process in the unconventional horizontal wells. The production trend analysis and simulation results also indicate that the water oil ratio is closely related to the gas oil ratio, as shown in the attached Figure 2. For geologically similar area, higher gas oil ratio usually indicates higher water oil ratio.

 Novel/Additive Information:

There are very limited studies about multiphase flow in unconventional Liquid Rich Shale with extremely low permeability. There is no systematical study (i.e., numerical and field test to verify with actual production) about the oil/gas/water multiphase flow at Permian reported.