DRILLING & PRODUCTION

The Equalizer system well screen controls sand and resists plugging and erosion with three concentric layers of media — a protective shroud, a single-layer vector filtration membrane, and an inner jacket.

Optimal reservoir drainage is a challenge when producing from extended-reach horizontal and multilateral wellbores, even in formations with uniform permeability. When alternating high- and low-permeability strata are penetrated by a long wellbore, or when high permeability exists at either the heel or toe of a lateral section, the tendency to lose production through various parts of the reservoir increases.

“Optimal production from long, low drawdown, high rate horizontal wells often requires more than sand control, so the Equalizer system also provides production optimization,” explains Baker. “The system balances, or equalizes, longitudinal inflow along the entire length of a wellbore. A uniform production profile ensures reduced influx of water or gas into the wellbore.”

To delay water or gas coning in horizontal wells, the system uses an extended-life well screen and an inflow control device as a restrictive element. The well screen controls sand, and resists plugging and erosion with three concentric layers of media — a protective shroud, a single-layer vector filtration membrane, and an inner jacket. The outermost layer of the screen is a vector shroud for erosion protection under turbulent flow. Within the shroud, the single-layer vector membrane has uniform pore throat openings and an inflow area of about 30%, 10 times that of a typical pre-pack screen. The inner jacket and drainage layer protects the overlying vector membrane layer from high differential pressure. These features combine to extend screen life to eight times that of a standard pre-pack screen, Baker says.

The inflow control device uses a restrictor element to distribute pressure along the entire length of a wellbore. Thus, local production rates at any point along a wellbore can be controlled as a function of both the average drawdown pressure and the average well productivity.

The operator supplies formation data as input for mathematical modeling and to configure individual systems for optimal pressure drop and flow rates. The system applies to a variety of wellbore conditions, including those that require viscous fluid, kill pill cleanup, or multiphase flow. Also, this system has attained individual lateral installation lengths of more than 13,000 ft (4,000 m) since its introduction in 1998.

Optimizing perforating, fracturing strategy

The oilfield technology group of Hexion specialty chemicals has developed a new environmentally improved PropTrac HSM fracture diagnostics technology to determine proppant location. This patent-pending technology allows operators to optimize perforating and fracturing strategy to increase oil and gas production, according to Hexion.

The actual downhole fracture geometry can affect the economic value of a well. Having a better understanding of fracture dimensions allows operators to make more informed decisions and to optimize well completion designs to enable the wells to produce to their full potential. An example is an unconventional reservoir such as tight gas and shale. A major technical challenge in this circumstance, especially multi-zone, is correlation of post frac production performance with both the reservoir’s properties and the completion procedure.

PropTrac H is designed to optimize fracture treatments and improve results. The resin coated proppants contain a proprietary, non-radioactive tagging material in the coating. Once the well is fractured, these proppants are temporarily activated downhole with a special logging tool that identifies their location. Unlike some radioactive tracers, this technology is no longer active by the time the tool is removed from the well. The technology can also be activated repeatedly to log wells months, even years, later to determine what zones were actually fractured with the proppants.

This technology benefits are:

• No radioactive tracer materials
• Does not require the same environmental or safety precautions, permits, or regulatory compliance as radioactive tracers
• Logs can be run as often as desired during the lifetime of the well
• Proppants with a built-in tagging material in the resin coating provide more accurate results.

Some operators are using proppants as “insurance.” They are only logging the well if necessary due to lower than expected post-treatment production.

As an example, this aids engineers in calibration of their frac design model with a “real-world” proppant distribution log. Additionally, logs are provided that show where operators can perforate additional zones to potentially increase well production. It also allows users to observe how proppant distribution in the fracture may be affected by changes in flowing pressure, flow rates, or fluid entry. This technology can provide additional data for analyzing changes in production rates (such as decreases) and help explain these changes, e.g., the proppant pack shifted in the fracture. Operators can also use this information to assist in analyzing refrac options during the well’s lifetime.

In combination with other well information, this technology can provide operators with insight into where not to fracture such as zones producing large amounts of water and even contaminated water from possible radioactive zones. Completions and fracturing designs derived from this information can help to reduce or prevent the production of such unwanted fluids. Knowing fracture heights aids in perforating where hydrocarbons are inclined to accumulate above unwanted water, allowing operators to reach additional deposits. This technology can assist fracture design engineers with improvements in future offset well completions by analyzing changes in perforating density, fracturing treatment rate, and fluid viscosity.

The data received from this technology is compiled into a report for scientists and engineers to evaluate for insights on the best methods to improve well completions.