Tight Oil Drilling Problems and Solutions

Crude oil, also known as petroleum or fossil fuel is found in some rock formation deep below the earth’s surface. Tight oil is a unconventional oil that is found in reservoirs with very low permeability. The oil contained within these reservoir rocks will not flow to the wellbore at economical rates without assistance from technologically advanced drilling and completion process (Canadian Society for Unconventional resources). For tight oil reservoirs, matrix permeability plays a key role in determining drainage area for each well and the optimal well spacing. In this work, steady-state method to measure liquid permeability on intact core plugs from tight oil bearing rock under reservoir stress condition will be presented.

Techniques for quantitative analysis of ultra-low permeability reservoirs completed with hydraulic fracturing and horizontal wells are in their infancy. Complications that have shown the development of these techniques include complex reservoir porosity such as dual porosity effect, multi-layer behavior, multiphase flow and non-static absolute permeability and complex flux behavior associated with the simultaneous flow of multiple hydraulic fracturing into horizontal wells. Drilling problems to access the wellbore and solutions will be discussed.

Investigating the application of enhanced oil recovery method is essential. Carbon dioxide (CO₂) injection as a huff-n-puff process is a preferred approach to improve oil recovery in tight reservoirs. The effect of molecular diffusion will be investigated. A series of sensitive studies to quantify the impacts of reservoirs properties such as permeability and fracture properties (fracture half-length, fracture conductivity, the number of fractures, and operation parameters) will be performed. The operation parameters such as CO₂ injection rate, injection time, soaking time, the number of cycle CO₂ diffusivity on CO₂ huff-n-puff process for enhanced oil recovery in the Bakken Formation will be discussed.