The choice of gas lift for unconventional shale plays is proving reliable and, in most cases, the lowest lifting cost per barrel when suitably applied. Current horizontal drilling and completion technology have provided many challenges in today’s daily production practices. Starting out as high fluid and gas rates carrying large quantities of frac sand to surface, flush production from shut ins (+- 10,000 ft HZ) and declining reservoir pressures has compelled operators to reevaluate long term lift choices.

Commonly production ranges start between 2000-5000 BLPD with gas rates greater than 2 MMCF day and associated water cuts between 50-100% or what could be called frac fluid recovery while  lifting / producing these rates from 10,000+feet TVD .Applying a design to kick off well initially, allowing to let flow and then operate 1-2 years later when production rates are down to less than 500 BLPD creates  enormous challenges particularly when based off historical industry design procedures. The single biggest deterrent is the unloading practices used by operators.  

What we once knew as “Multi Point” injection was more than likely gas lift intermitting between two or three valves. With today’s gas lift, Multi Point injection is more likely the required injection gas volume being distributed through two valves with no intermitting at all. IPO valve port sizes play a big part and experience has shown some positive results

Understanding valve performance and how it relates to possible multi point injection is vital. A typical temperature swing between static, initial flowing to future flowing temperatures is a gas lift engineers worst nightmare when using N2 charged IPO valves. This temperature range is frequently between 100 F up to 220F for upper valves.

 Smaller ports offer the advantage of less tubing effect / greater casing stability but have a reduced gas passage capacity. Larger ports may pass the required volume but creates the opportunity to reopen a valve above with a large fluid tubing slug. Understanding the IPO valve port sizes and how they play a big part in daily operations has shown some positive results.

Using NODAL programs combined with VPC or other dynamic simulators provides greater simulation of injection gas volume distribution relating to critical velocities.