Stimulation Video

As an extension to my last post, here is a video that shows the basics of the hydraulic stimulation of a well.  The video also shows the basics steps to followed to drill a horizontal well which is the majority of the type of wells being drilled today.

What is a Frac Job?

I've had several posts on frac jobs of oil and gas wells.  It is actually a complex process and there is a lot of chemistry that goes into the design of a frac.  Each frac is specific to the well and its properties such as pressure, temperature, pH level, lithology, and others.  Thousands of gallons of water are used for frac jobs and very miniscule amounts of chemicals (.004% per thousand gallons of water) can completely alter the properties of the fluid .  The idea of a fracture job is to create a super highway for hydrocarbons to travel into the producing wellbore.  The shape charge perforations which I explained in earlier posts are the first step to the job.  The frac fluid is pumped into the wellbore and uses a crosslinker to suspend sand proppant and carry it into the perforation.  The crosslinker can vary from fluid to a solid composition such as one that Schlumberger uses.  The crosslinker can be modified to delay the conversion of the fluid into gel so optimization of sand suspension and placement can be achieved.  The type of sand used depends on the pressure encountered at the fracture.  Some sand can be crushed if the pressure is too great and man made ceramics can be used in these cases.  Once the gel has carried the sand into the fractures to create a super hydrocarbon highway, a breaker is added to return the fluid system to a less viscous state.  The fluid is pumped back to surface returning the majority of chemicals and additives in the fluid system to tanks on surface while leaving the proppant to maintain the fracture open.  This method of stimulating a well has become routine for nearly every well drilled in order to enhance production.  This method is the technology driving these tight gas sands and shale research for economic production of new reservoirs being discovered today.  Multiple zone fractures are highly common and a 3D image is seen below to monitor the effectiveness of a hydraulic fracture stimulation job.  Each color represents a different zone.

A frac job also requires a lot of hydraulic horsepower.  This is achieved by connecting several pump trucks ranging from 1000 hp to 3000 hp each to a unit called missel located in between the group of all the trucks.  

Video Blog

Here is my very FIRST video blog post ever.  It's a little hairy, didn't really know what I was doing or what I wanted to talk about exactly, but there's some good background info about the drilling industry.  Enjoy!

Blog Evaluation #2

Frac for more oil.

This post is to add a little more on the last post as well as to give you a good laugh.  Fracturing and stimulating wells, to increase hydrocarbon production, has angered many people in terms of ground water contamination.  Groundwater contamination can be due to many other things rather than just drilling and stimulation, such as land fill waste, factory or plant waste disposal and other things.  The blame seems to be entirely aimed at drilling activity however.  Fracturing occurs in zones which contain hydrocarbons.  These reservoir zones are typically 8,000 feet deep or can be up to 12,000 feet in deeper wells.  This is the depth at which hydraulic fracturing and acidizing takes place.  The groundwater aquifer is near 100 feet deep and not remotely close to the fracturing chemicals being used to stimulate reservoirs.  The chances of these chemicals traveling through several alternating impermeable layers of rock to the groundwater source is very very unlikely.  Just another example of blame being fired at oil companies when other sources of contamination are igonred during the first steps of pointing fingers.  Below is a hilarious video (possibly slightly improper) in my opinion that doesn't have much to do about actual fracturing of wells but none the less will provide a good laugh.  Enjoy!



Drilling.....Safer than walkin' across the street blindfolder.

My last couple of posts have been about drilling's interaction with the environment and regulations which are strictly enforced to protect it.  I will continue with that subject in this post and talk a little more about regulations.  There are basic steel pipes which are called casing and are set in the wellbore in order to provide zonal isolation as well as wellbore stability.  Surface casing is VERY important in order to isolate groundwater (drinking water) from drilling fluids and chemicals used to acid fracture or stimulate reservoirs.  Groundwater is typically around 100' deep and is often isolate by conductor casing which is the very first section of casing set when drilling.  State regulations vary, but a relatively standard regulation is that surface casing must be set minimum of 300' below the bottom of the ground water zone and cemented properly.  Cement bond logs, which are legally required, test the integrity of the cement and make sure complete zonal isolation is achieved.

Many people have accused drilling companies to have contaminated ground water, but the fact is that strict regulations and monitoring of drilling through permits has been in the industry for many years and continue to become more strict as the years progress in order to mitigate these problems.  Members of the Oil and Gas Conservation Commission presented in one of my classes this week and confirmed the increase in regulations of drilling are unavoidable.  These regulations include well spacing also, where wells being drilled have to go through a specific permit in order to ensure adequate acreage spacing between other wells.  They discussed a situation where a farmer's groundwater was suspected to have been contaminated with methane gas from a nearby well.  Immediate action was taken by conducting CBL's as well as sampling gas from the well and the farmer's water.  It was determined that a bad cement job of the casing had allowed gas to travel in between the intermediate and production casing and enter the water zone.  Cement squeeze jobs can be conducted in order to fix cement job problems such as this one, but the OGCC realized the matter was of huge concern and violation of regulations.  The operator of the well was required to plug and abandon the well and lose money from shutting down of production from the well as well as abandoning material costs.  Plugging and abandoning a well also has strict and strongly enforced regulations by states.  As Capt. Carbon Sequester mentioned on my last post, other industries have had failures as well such as the Minneapolis bridge collapsing.  Sure the bridges were subject to more strict inspections, but the civil and mechanical engineering industry did not take such huge hits as big oil companies, or small companies, have taken over many smaller incidents over the years.  Individuals need to become more informed about the regulations drilling operations are required to follow and possibly see the side that extreme caution is being take when trying to suffice the U.S.'s hunger for more oil by drilling oil and gas wells.  What do you think about that?

Can I drill here anyway!?.....NO!!!

I often hear drillers labeled as people who don't respect or protect the environment.  Well that may be true if the environment interaction is compared to that of someone who may like to give a tree a hug from time to time.  The fact of the matter is however, there are very strict regulations which drillers must follow in order to execute drilling a well.  Surface permits are the major step to drilling.  Over field session II during my Junior summer, we learned a little bit about permits in the oil and gas industry.  I could not believe some of the things preventing a drilling operation.  There was a particular species of cacti which was considered endangered.  A team of professionals from the oil and gas company went out to get a better look at the location and a small bud of the cactus, "about the size of a pencil eraser," was ran over by a four wheeler.  These small growing plants were being tracked by some method of gps and the company was in fact issued a fine for the cactus which was barely visible to someone who may know the exact location of it.  Prairie dogs were also another issue as they are vastly spread in rural areas.  They are actually a headache for farmers and ranchers in many areas and extermination of them would not hurt any feelings.  So basically, the worthless rodents have more of a right to the land than individuals.  How does that make you feel?

Aside from surface rights which can also include sacred Indian grounds, national grounds, and others important areas, there is more to it than simply a surface permit.  Well plans such as casing design and wellbore trajectory must also be reviewed.  Proper zonal isolation is a MUST in the industry as well as staying in the required boundaries.  Cement Bond Logs (CBL's) are actually required.  This measures the structural integrity of the cementing jobs which are used to isolate zones such as groundwater zones.  Drilling technology is making the ability to stay in required boundaries easier as it progresses.  These permits can be several inches in thickness of stacks upon stacks of paper and can take several years to be approved.  If a change in the well plan is found to be necessary during the process, changes have to be reported to the legal agency in charge of the permit and has to be cleared for further drilling.  Drillers may not have as particular urges to save a tree or two as others, but none the less, are legally required and in fact take drastic measures in an attempt to be "friendly" to the mother earth.