Operators focused on stripper wells typically fall into one of two camps.
The first is trapped by capital and technology constraints. They are relegated to pump & rod maintenance, hot oil treatments, and resulting low production rates. If they act early enough, they can put in a few water injectors to bump up field economics before the overall field production drops. If they don’t act quickly enough, they have to go into debt to drill injection wells and hope for a payback.
The second group usually has a large enough asset base to move up to tertiary recovery if they are located close enough to a CO2 source. The industry has been largely following these 2 approaches since the 1970’s when field wide CO2 flooding was first used to stimulate production in stripper wells.
Stripper Wells & Micro-Bore Jet Drilling
What most folks don’t realize is that over the last 10 years there have been technology advancements that can economically fit in the gap between secondary and tertiary recovery. This technology can improve recovery factors and rates in stripper wells without spending millions on infrastructure and new wells. These two technologies are Micro-Bore Jet Drilling (MBJT) and Nitrogen based miscible gas injection.
Micro-Bore Jet Drilling uses a high-pressure fluid injection system to literally erode the rock matrix and create a 1-2″ diameter hole. Penetration rates can approach 250ft/hr in high porosity sands. The jetting assembly can transition from vertical-to-horizontal within as small as a 4 1/2″ wellbore. This is a rigless drilling process where you just need a small pulling unit to trip in the BHA on tubing and then run the drilling assembly to bottom.
The drilling assembly works like a giant hypodermic syringe where slacking off at the surface pushes a downhole plunger. The plunger advances the jetting nozzle into the rock face where it removes material. Through control drilling, holes can be created with a surface area equivalent to a conventional 6″ wellbore. A half dozen or more micro-bore laterals can be jetted at a single depth. This creates what’s essentially a TAML Level 1 or open hole multi-lateral system.
Jetting these laterals with formation water allows you to create skin-free, conductivity channels in your reservoir. The extremely short kick-off ability allows you to target thin beds behind pipe that aren’t economic to test with conventional sidetracking methods. Water coning can be avoided by jetting laterals at the top of a zone to make maximum use of a water drive. There are many, many other uses for these cheap, high conductivity reservoir drainage or injection pathways.
While increasing reservoir draining per well is one way to increase production, if there’s no energy or pressure left in the pore space, oil will only flow be at a snail’s pace. You need a way to re-energize the rock matrix without spending millions on pipelines, CO2, and high chrome tubulars.
Stripper Wells & Nitrogen Gas Injection
A highly-economic nitrogen-based, miscible gas injection fits in the gap between secondary and tertiary recovery. Traditionally when we think of Nitrogen injection, we think of cryogenic or membrane separation. These require extremely high injection pressures to achieve miscibility.
What if we took a completely different approach?
What if you were able to use a mobile unit to create a hot, pressurized, gas, with extremely low miscibility pressure? What if you could put plant-based paraffin and ashphaltene treatment chemicals into a vapor state to clean stripper wells without hot oil? What if you could then inject the same hot gas into the rock matrix to reduce the oil viscosity? Moreover, what if you could “touch” a huge volume of oil in the pore space so oil flows longer and faster to the wellbore?
The anchor client for this new technology tripled field production in 6 months while only working over 1/3 of the field’s stripper wells. They’ve now been using the system for over 6 years with no problem maintaining field production rates.
The mobile units require just $50/hr in fuel and stripper wells are usually treated in just 2-3 hours. They are then left to “soak” for 12-24 hours so the pressurized gas including the viscosity modifying chemicals can permeate the rock matrix and have a longer lasting production enhancement effect.
It’s rare that technologies come along that are truly game changers in a market segment. On their own, each technology may not be the game-changing solution that it first appears to be which in turn inhibits its market acceptance.
For instance, I’ve seen shallow vertical stripper wells converted with the MBJT method and experience initial production increases of 600% which then quickly tail off. When a camera was run into the well, the laterals were completely plugged with paraffin. By addressing the reservoir drainage issue without addressing the paraffin inhibition issue or reservoir energy issue, we’ve only solved part of the problem. Without the extra information that the camera provided, we would have walked away and said that drilling laterals don’t have an impact on production.
What really struck me was operators in PA where this field was located, have been doing mini-fracs for 50 years to enhance production in stripper wells.
They didn’t realize once reservoir pressure and temperature dropped close to the oil’s cloud point, paraffin precipitates. This happens as soon as oil jumps from the pore space to the fracture or wellbore. With the mini fracs, what started out as a conductivity enhancement treatments soon turned into hydrocarbon flow barriers. At those shallow depths, they are creating horizontal pancake fracs. Over time each of those discs of sand turn into paraffin filled flow barriers which are very, very hard to remediate.
Stop the Insanity
We’ve all heard that the definition of insanity is doing the same thing over and over again but expecting a different result. It’s time to stop the insanity and give these stripper wells a little love by evaluating new options. We need a scientific approach to their enhancement rather than following the recipes of 50 years ago.