The Oil Kitchen Rules

[thackney]

The Oil Kitchen Rules

How Geologists Interpret Ancient Environments; Oil is a Part of the Rock

As a kid growing up in NZ, my only contact with ‘O&G’ was watching my Dad filling the family car with (at that time leaded) gasoline, and Jed Clampett watching black gold oozing from his backyard.  Jed and his family had to forgo the possums, grits and cat’s paws for the rarefied atmosphere, with a twist of lemon, of Beverly Hills.  They had made their fortune on Texas Tea like countless others have done since.

Modern societies depend hugely on hydrocarbons (oil and gas), either directly or indirectly; fuels, plastics, construction, medicines, communications, space travel, renewable energy – the list goes on.  It is easy to forget that oil, in its original form is, like water a geological fluid, albeit one that behaves differently to water.  Oil is part of the rock and it is inextricably involved in the formation of sedimentary rocks.

Humble beginnings

All hydrocarbons are organic chemical compounds.  Most (except vegetable extracts) are geological fluids.  Hydrocarbons are derived from two main sources of organic material; microscopic marine plankton, and terrestrial plants and algae.  In marine environments, especially seas that have high nutrients, various forms of plankton and small critters abound.  When they die they sink to the sea floor.  If waters near the sea floor are oxygenated, then much of this detritus will be scavenged by other bottom-dwelling critters, or the organic material will oxidize.  However, if the bottom-waters are anoxic (lack sufficient dissolved oxygen) then the organic detritus has a much greater chance of being preserved. If the sedimentation rate of non-organic muds and silts is also low then organic matter will tend to concentrate in layers (if sediment input is high the organic matter will be diluted).  Layers of organic-rich sediment are commonly referred to as black mudstones, black shales, or oil shale. Black shales, under the right geological conditions are the primary source of hydrocarbons.

Black shales, including oil shales commonly contain from 0.5% to more than 30% organic matter.  Some of these shales represent significant past anoxic events that can be traced over great distances, continent-wide and even globally.  As such they can tells us a great deal about some rather unsavoury environmental conditions in the distant past.  One such event about 94 million years ago (Cretaceous Period) occurred when global climates were very warm (no icecaps), when CO2 levels in the atmosphere were high (Hothouse conditions), and when there was significant volcanism.  The oceans, especially the deeper parts became deficient in oxygen on almost a global scale.  There are very few marine critters that like living in these conditions.  An important consequence of events like these is the extinction of significant marine life.



A kitchen brew

Sediments undergo major changes as they are buried deeper and deeper by other strata.  The increasing weight of overlying sediment leads to compression, that in turn expels fluid, usually modified seawater.  These fluids promote chemical reactions.  Increasing depth in the earth’s crust also means increasing temperature; the global average is about 25oC per kilometer depth (also known as the geothermal gradient), but there is a fair bit of variation depending, for example on the age of the crust (older crust tends to be colder) and proximity to sources of magma.  An important consequence of these changes is that new minerals can form in the open pores; these minerals precipitate from saline water that continually percolates through the buried sediment.  Quartz, calcite and clays are most common and their formation helps to cement the once loose sediment into hard rock.




Organic matter also undergoes significant transformations as it is buried and heated.  The original material, whether cellulose, algae, or plankton, begins to break down almost immediately after it accumulates on the sea or lake floor or in a peat bog; this process accelerates as temperatures increase during burial.  The insoluble products of this breakdown process produce complex organic molecules called kerogens and it is the continued transformation of kerogen that eventually leads to the formation of hydrocarbons. Different kinds of kerogen (e.g. algae or plankton) promote different hydrocarbon products; marine plankton and algae generally result in oils, whereas woody tissues and plant material will promote a mix of oil and gas, or just gas.

The breakdown of organic matter also results in soluble compounds, especially organic acids including acetic acid (aka vinegar).  These organic acids play a significant role in the cementing of rocks or dissolution of minerals such as calcite, especially by regulating or buffering acidity (pH).  Thus, the formation of hydrocarbons is an integral part of the transformation of sediment to rock.

The transformation of kerogen to various hydrocarbon products is greatly accelerated at about 80oC, corresponding to a burial depth of about 3 km.  The window of accelerated oil production extends to about 120o-130oC; it is commonly referred to as the oil generation window.  At higher temperatures there is an increasing tendency for the organic chemical reactions to produce gas.  From a geological perspective, the temperature range 80o to 130oC is also the window in which other rock-forming processes are most reactive, especially those that promote either the precipitation or dissolution of minerals and mineral cements.



Migration

Organic, kerogen-rich shales that have been buried deep enough to enter the oil generation window have entered the hydrocarbon kitchen.  As hydrocarbons are produced, the new fluids move (slowly) through the shale and into more porous sandstones or limestones.  This stage is referred to as migration. The main driving force for migration is buoyancy; hydrocarbons have lower specific gravity than fresh water and brines and will tend to displace water as they move through the more porous rocks.  Migration continues until either the hydrocarbons are trapped by less permeable strata, or they will continue through the strata and if unimpeded will eventually escape at the sea floor or seep at the land surface.  Natural oil and gas seeps are common in many oil-provinces around the world.  An example of trap-like structures is shown in the photo at the top of this post.

The entire process of initial deposition, burial by other sediment, cooking in the kitchen, migration and final trapping takes millions of years.  It all happens very slowly.  Oil and gas trapped in this way is also naturally sequestering carbon.  The hydrocarbons will stay trapped until the trap is disturbed, for example by faults and fractures that oil can leak from, or until someone discovers the deposit and pumps it out – at which point…  .

Here are some sites with animations of oil formation   and migration.  Also some teaching resources

Links at source

[IsailedawayfromFR]

The Oil Kitchen Rules

How Geologists Interpret Ancient Environments; Oil is a Part of the Rock

Links at source

This is one our moderator needs to weigh in on.

[alicewonders]

This is one our moderator needs to weigh in on.

@Lando Lincoln

[Smokin Joe]

This is one our moderator needs to weigh in on.

From reading over the post, it is a good basic summary.

Keep in mind that while a marine (seawater) environment is the most common, that lakes can provide the conditions needed to accumulate oil generating strata.

The Green River Oil Shale found in Wyoming, Utah, and Colorado are lake sediments, not marine ones, for instance, and I have seen oil in Nevada that also came from lacustrine sources.

When a geologist speaks of "thermal maturity", that is the situation where rocks have been subjected to the temperature/pressure combinations which generate oil.  If the sediments are not yet thermally mature, given all else there may be some methane. As that thermal maturity increases, oil develops (with some natural gas), and beyond that, at higher temperatures and pressures, the longer hydrocarbon chains tend to break down into natural gas.

It takes a combination of factors to have a successful reservoir (one which can be economically produced), and even leaving technology and market factors out, what is needed is a source rock full of organics (plankton is far more important than dinosaurs), a porous rock to accumulate the oil in, a seal or cap rock to prevent the oil from escaping, and enough thermal maturity to generate the oil.

Beyond that, we need a mature enough government to let us drill the wells and produce it.

[IsailedawayfromFR]

From reading over the post, it is a good basic summary.

Keep in mind that while a marine (seawater) environment is the most common, that lakes can provide the conditions needed to accumulate oil generating strata.

The Green River Oil Shale found in Wyoming, Utah, and Colorado are lake sediments, not marine ones, for instance, and I have seen oil in Nevada that also came from lacustrine sources.

When a geologist speaks of "thermal maturity", that is the situation where rocks have been subjected to the temperature/pressure combinations which generate oil.  If the sediments are not yet thermally mature, given all else there may be some methane. As that thermal maturity increases, oil develops (with some natural gas), and beyond that, at higher temperatures and pressures, the longer hydrocarbon chains tend to break down into natural gas.

It takes a combination of factors to have a successful reservoir (one which can be economically produced), and even leaving technology and market factors out, what is needed is a source rock full of organics (plankton is far more important than dinosaurs), a porous rock to accumulate the oil in, a seal or cap rock to prevent the oil from escaping, and enough thermal maturity to generate the oil.

Beyond that, we need a mature enough government to let us drill the wells and produce it.

Can I add that in the present technological environment, in certain cases ( i.e -what is most being drilled in this country), one needs a rock sufficiently brittle so as to be effectively fracced?  Ductile rocks like shales just have a very poor chance of responding well to the creation of fracture systems, whether naturally or artificially, which means the oil may be present, but unlikely to make commercial producing wells.  The Bakken shales are notable examples.

[Smokin Joe]

Can I add that in the present technological environment, in certain cases ( i.e -what is most being drilled in this country), one needs a rock sufficiently brittle so as to be effectively fracced?  Ductile rocks like shales just have a very poor chance of responding well to the creation of fracture systems, whether naturally or artificially, which means the oil may be present, but unlikely to make commercial producing wells.  The Bakken shales are notable examples.

Interesting you should mention the Bakken Shales. The Lower Shale is known to be serious trouble for excursions from the upper Three Forks or lower Middle Bakken precisely because it will slough with such rapidity that it will stick the drill string. In areas where infill wells are drilled following wells that have been fracced, the shale cuttings are about like coffee grounds--even the slough. and on the Nesson Anticline just south of Tioga, I recall seeing the shales in core which although natural fractures were healed with calcite, the orientation scribes in the core barrel induced fractures in the shale. Unlike much other shale I have seen, the organic content is so high they tend to be brittle.  Compared to the shale in the lower Three Forks (relatively low organic content, and older) and Shale Formations like the Pierre, Cody, Mowry, and others they are far less ductile, and are considerably different in character. In drilled samples, the cuttings look like coal more than shale.

In the Bakken, the preferred target is the lower half of the upper 20 ft of the Middle Bakken in the deep part of the Basin, which affords room to avoid the shale and proximity to if not direct passage through the better porosity.

Different oil companies have different strategies, and vary from being concerned with staying with the lower gamma ray signatures in the interval where present to just selecting a track that should cut through the general area of the better rock and letting the frac do the rest, while avoiding shale contact.

The Middle Bakken lithology varies, and I have seen everything from pelletal Limestone in northern Dunn County ND (south of the River), to very fine sand/siltstone to (sometimes silicified) microsucrosic to sucrosic dolomite, depending on where you are in the Basin, and sometimes a mix. The Elm Coulee Field wells I worked had the most consistent lithology, and in the deeper basin it varied, depending on where you were.

The Bakken Shales are plenty brittle, but a great deal of the generated oil had already escaped to the Middle Bakken and Upper Three Forks (and Pronghorn, where present). When the wells were drilled in the mid 80s, few reached payout because they drilled in the shale, and and not in the adjacent Middle Bakken and Upper Three Forks reservoirs.

The first Bakken well I worked was in 1980, quite by accident, on the Billings Nose. We drilled into the Middle Bakken and took a kick. It wasn't the well target, but the 4 feet of perfs in the top of the Middle Bakken produced 580MCF of gas and 70 bbls of condensate a day IP. The actual targets for the well were the Fryburg and Duperow.

I found out later that other wells had been made in the Bakken in other parts of the Basin, all vertical, most by serendipity, not design, as the Bakken was not the intended deepest target (often Red River or Interlake).  Those, however, were vertical wells, not horizontal wells. The Bakken was notoriously difficult to Drill Stem Test in open hole (mainly because of the brittleness of the shale), and most operators simply consigned it to something to check out before P&Aing a well that had produced from deeper targets.

It wasn't until interest was revived in horizontal drilling for carbonate targets (my first was in 1990 in MT) and after much of the Bowman area (ND) Red River play had been drilled, that drilling in what would become the Elm Coulee Field began, and I was lucky enough to have been working for a client who had an itch to check that out early on.
We drilled an infield well in Richland County, MT, with a Red River Target, and I saw what I knew the other companies were looking at in the Bakken in samples from that wellbore. While we made a very good well in the Stonewall Fm., and the client didn't want to mess with that, we did come back after a couple of more vertical wells and drill their first Bakken Lateral. That was pretty much the end of my evaluating vertical wellbores, back in 2001, from then on, it was horizontal wells in the Bakken or Three Forks.

[IsailedawayfromFR]

Interesting you should mention the Bakken Shales. The Lower Shale is known to be serious trouble for excursions from the upper Three Forks or lower Middle Bakken precisely because it will slough with such rapidity that it will stick the drill string. In areas where infill wells are drilled following wells that have been fracced, the shale cuttings are about like coffee grounds--even the slough. and on the Nesson Anticline just south of Tioga, I recall seeing the shales in core which although natural fractures were healed with calcite, the orientation scribes in the core barrel induced fractures in the shale. Unlike much other shale I have seen, the organic content is so high they tend to be brittle.  Compared to the shale in the lower Three Forks (relatively low organic content, and older) and Shale Formations like the Pierre, Cody, Mowry, and others they are far less ductile, and are considerably different in character. In drilled samples, the cuttings look like coal more than shale.

In the Bakken, the preferred target is the lower half of the upper 20 ft of the Middle Bakken in the deep part of the Basin, which affords room to avoid the shale and proximity to if not direct passage through the better porosity.

Different oil companies have different strategies, and vary from being concerned with staying with the lower gamma ray signatures in the interval where present to just selecting a track that should cut through the general area of the better rock and letting the frac do the rest, while avoiding shale contact.

The Middle Bakken lithology varies, and I have seen everything from pelletal Limestone in northern Dunn County ND (south of the River), to very fine sand/siltstone to (sometimes silicified) microsucrosic to sucrosic dolomite, depending on where you are in the Basin, and sometimes a mix. The Elm Coulee Field wells I worked had the most consistent lithology, and in the deeper basin it varied, depending on where you were.

The Bakken Shales are plenty brittle, but a great deal of the generated oil had already escaped to the Middle Bakken and Upper Three Forks (and Pronghorn, where present). When the wells were drilled in the mid 80s, few reached payout because they drilled in the shale, and and not in the adjacent Middle Bakken and Upper Three Forks reservoirs.

The first Bakken well I worked was in 1980, quite by accident, on the Billings Nose. We drilled into the Middle Bakken and took a kick. It wasn't the well target, but the 4 feet of perfs in the top of the Middle Bakken produced 580MCF of gas and 70 bbls of condensate a day IP. The actual targets for the well were the Fryburg and Duperow.

I found out later that other wells had been made in the Bakken in other parts of the Basin, all vertical, most by serendipity, not design, as the Bakken was not the intended deepest target (often Red River or Interlake).  Those, however, were vertical wells, not horizontal wells. The Bakken was notoriously difficult to Drill Stem Test in open hole (mainly because of the brittleness of the shale), and most operators simply consigned it to something to check out before P&Aing a well that had produced from deeper targets.

It wasn't until interest was revived in horizontal drilling for carbonate targets (my first was in 1990 in MT) and after much of the Bowman area (ND) Red River play had been drilled, that drilling in what would become the Elm Coulee Field began, and I was lucky enough to have been working for a client who had an itch to check that out early on.
We drilled an infield well in Richland County, MT, with a Red River Target, and I saw what I knew the other companies were looking at in the Bakken in samples from that wellbore. While we made a very good well in the Stonewall Fm., and the client didn't want to mess with that, we did come back after a couple of more vertical wells and drill their first Bakken Lateral. That was pretty much the end of my evaluating vertical wellbores, back in 2001, from then on, it was horizontal wells in the Bakken or Three Forks.

Very informative review of the history of the growth of the present plays.  Sometimes it is a matter of stepping out to see what might happen in order to achieve success, as the story of the Bakken play is told as you so well did. 

I gather that the answer is yes, one needs some brittleness to acquire commercial success. 

I knew Rob Sterling when he worked at Cirque and he had related to me some of what you described, although he did not have the in-depth history that spanned the years you relayed.

In one part of the basin where I worked we could make some wells that could naturally flow +1000 PLOd without fraccing in the MB as the natural fractures systems were so prevalent.  Not the rule, but could be done.

Wells that could flow without fraccing were always PLO, but when we fracced them, we invariably brought in prodigious amounts of water.  Where do you think this water came from?

[EC]

Help an ignoramus out?

How do you drive a horizontal well?

Shafts, I get, and even that you can bend the shaft quite a way off vertical over a long enough run by using an asymmetric drilling head. (I assume one side of the head cuts more aggressively than the other, forcing the shaft in it's direction).

But how on earth do you do a horizontal drilling from the surface?

[IsailedawayfromFR]

Help an ignoramus out?

How do you drive a horizontal well?

Shafts, I get, and even that you can bend the shaft quite a way off vertical over a long enough run by using an asymmetric drilling head. (I assume one side of the head cuts more aggressively than the other, forcing the shaft in it's direction).

But how on earth do you do a horizontal drilling from the surface?

Smokin Joe is the expert.

@Smokin Joe

[thackney]

How do you drive a horizontal well?

Some basics:

A horizontal well is a type of directional well, when the inclination exceeds 80 degrees from vertical, or when the lower part of the well bore parallels the pay zone. Horizontal wells are drilled to increase the length of the well that actually contacts the reservoir, in order to increase the productivity of the well.

How Does Directional Drilling Work?
http://www.rigzone.com/training/insight.asp?insight_id=295

Directional drilling has been an integral part of the oil and gas industry since the 1920s. While the technology has improved over the years, the concept of directional drilling remains the same: drilling wells at multiple angles, not just vertically, to better reach and produce oil and gas reserves. Additionally, directional drilling allows for multiple wells from the same vertical well bore, minimizing the wells' environmental impact.

[Weird Tolkienish Figure]

Not impossible to imagine as car drive-shafts transfer power from the engine to the axle at odd angles. I'd imagine something similar exists for drilling.

Fascinating stuff.

[IsailedawayfromFR]

Not impossible to imagine as car drive-shafts transfer power from the engine to the axle at odd angles. I'd imagine something similar exists for drilling.

Fascinating stuff.

Another application of use of horizontal drilling is for pipelines underneath highways and rivers/lakes.

Same principle.

[thackney]

Not impossible to imagine as car drive-shafts transfer power from the engine to the axle at odd angles. I'd imagine something similar exists for drilling.

Fascinating stuff.

Often it is different than the rotating string of drill pipe, but rather using a mud motor that turns separately from the drilling string.

Pumping the drilling fluid through the motor turns the drill bit and then carries the cuttings back to the surface.





But there are a varieties of tools and technology developed over the decades to accomplish the task with greater efficiencies.

[EC]

I'm just amazed you can get that amount of flex. Neat, thank you for the lesson!

[Weird Tolkienish Figure]

My guess is that the CV joints are where it flexes?

https://en.wikipedia.org/wiki/Constant-velocity_joint

[Smokin Joe]

I'm just amazed you can get that amount of flex. Neat, thank you for the lesson!

It is a matter of progress by degrees. Most of the mud motors we used in the Williston Basin (Bakken) would make a turn with a radius of roughly 400 ft., drilling an 8 3/4 inch diameter wellbore. The severity of the turn is controlled (to some extent) by either orienting the mud motor so the bend is set to maximize the angle build or to some offset from that to reduce efficiency in building angle (or rotating the entire assembly, which just doesn't increase hole angle and can cause that to drop).
An easy way to envision it is to take a bendable straw, bend the end, and hold the long side. Now look down the side of the straw and envision that being able to cut a hole at the end of the straw. As that end drills (holding the straw steady), it will change the angle of the hole. If you want the angle to change quickly, you keep the bend pointed in the same direction, to be less efficient you either let the angle change or rotate the whole thing. The bend in most mud motors is less than 2 degrees, and some can be adjusted to more or less than that, although rotating a high angle mud motor downhole is usually a good way to break something.
The performance  (not just penetration rate, but steering performance) depends as much on the rock formation as the equipment used to drill it. In some rock types, the angle changes will be right at theoretical levels. In others, the change will be less, and the contacts between rock types will affect that as well.

Imagine pushing that bent straw through flour and then encountering a layer of crackers, and you might be able to see how that would work.

The best directional drillers can predict with reasonable accuracy what those changes in performance will be, both from data they have gathered and through the use of data others have gathered while drilling curves, and by working well with a good geologist who can tell them what sort of rock types and characteristics to expect. It is often best done with a good team effort.

While all that is going on, the MWD (Measurement While Drilling) crew takes surveys of hole angle and direction, and collects other information about the rocks obtained from sensors installed in the drill string for that purpose.

While drilling we most commonly used Gama Ray data for navigating what rock layer we were in, comparing information about the natural and varying level of radioactivity in the rock with offset or relatively nearby well information, or with the known characteristics of the rock layers to determine how many vertical feet were left to the pay zone, and confirming that with rock samples as we went.  Because some rock layers drill differently than others, the rate of penetration was also a guide to when we hit the Bakken Shale (or other strata, depending on the well), and often was the first indication of having penetrated the Upper Shale.  Keep in mind that the drill cuttings take time to get to the surface--at that point they have to be pumped through a couple of miles of well bore before they get to the surface, so early indicators which are accurate save time, which translates to about 50 dollars a minute for an onshore drill site.

[Smokin Joe]

My guess is that the CV joints are where it flexes?

https://en.wikipedia.org/wiki/Constant-velocity_joint

The CV joints allow the rotor to drive the bit sub past the angle in the mud motor and turn the bit. While the whole assembly can be rotated together, the mud motor allows the drill string to be kept steady at the surface while turning the drill bit with the bend oriented in the desired direction of hole deviation, whether that be building the initial angle, steering up, down, left, or right. Rotating everything more or less negates the influence the bend in the mud motor has on direction, and gravity has a tendency to take over, causing the angle to drop back toward vertical.

[Smokin Joe]

Very informative review of the history of the growth of the present plays.  Sometimes it is a matter of stepping out to see what might happen in order to achieve success, as the story of the Bakken play is told as you so well did. 

I gather that the answer is yes, one needs some brittleness to acquire commercial success. 

I knew Rob Sterling when he worked at Cirque and he had related to me some of what you described, although he did not have the in-depth history that spanned the years you relayed.

In one part of the basin where I worked we could make some wells that could naturally flow +1000 PLOd without fraccing in the MB as the natural fractures systems were so prevalent.  Not the rule, but could be done.

Wells that could flow without fraccing were always PLO, but when we fracced them, we invariably brought in prodigious amounts of water.  Where do you think this water came from?

Well, if you were getting those sort of flow rates without a frac, you had tied into some natural fracture systems, much like the vertical well I worked on the Billings Nose in 1980, and a couple of other 'surprise' wells I have worked in other areas.

I worked many non Bakken Horizontals in the Williston Basin as well, and one near Fryburg, ND, we got into a porosity that was only a few feet thick in limestone. The gas and oil shows were unreal, the layer just thick enough that the drill string could be rotated without leaving the porous layer (followed the desired path of least resistance) and we drilled a lateral down the structure in one direction, pulled back and drilled another lateral in the opposite direction, in the same zone up the structure, over the top, and down the back side in what was then record time.
 
When the operator went to produce the well, though, despite all indicators, the ocean came in (salt water). They were some savvy folks, though, and set a flow meter and packers in the well bore and identified the sources of the water. The water was coming from deep vertical fractures which tied in with other wet porosity zones and which preferentially flowed because of the incredibly high permeability along the fractures. When they set the packers between the closest fracture set and the vertical wellbore, they got oil.

I would suspect that by fraccing, those wells were tied into a similar water charged fracture system.

[Smokin Joe]

Another application of use of horizontal drilling is for pipelines underneath highways and rivers/lakes.

Same principle.

Yep! pipelines, power cables, all sorts of stuff that can be routed through a tube.

[IsailedawayfromFR]

I would suspect that by fraccing, those wells were tied into a similar water charged fracture system.

is the Bakken production water source above or below?

[IsailedawayfromFR]

I'm just amazed you can get that amount of flex. Neat, thank you for the lesson!

What Smokin Joe has laid out is more amazing when you consider that this is happening 2 miles below the surface of the earth and the horizontal portion is typically 2 miles long as well.

Everything is happening without any direct indicators, just indirect measurements and readings, and they have a lag response time as well.

I worked wells where the geologists were able to keep a well(called horizontal but actually followed the dip in the geologic formation, which makes it even tougher to drill) within a foot or two for 2 miles.

That is real incredible technology and geologic prowess.(smokin Joe - don't get a big head here)

[Smokin Joe]

is the Bakken production water source above or below?

In the Middle Bakken as well. Water saturation varies, depending on where you are, and generally (but not completely) structurally related. As a rule, you can get too low in the Middle Bakken and get water, but there again, fractures may play a significant role by providing permeability fairways.

[Smokin Joe]

What Smokin Joe has laid out is more amazing when you consider that this is happening 2 miles below the surface of the earth and the horizontal portion is typically 2 miles long as well.

Everything is happening without any direct indicators, just indirect measurements and readings, and they have a lag response time as well.

I worked wells where the geologists were able to keep a well(called horizontal but actually followed the dip in the geologic formation, which makes it even tougher to drill) within a foot or two for 2 miles.

That is real incredible technology and geologic prowess.(smokin Joe - don't get a big head here)

Mother Nature has thrown enough spitballs and sliders that I find the more I learn the less I 'know'.  You have to stay on top of it, even if (sometimes especially if) it seems like an 'easy' well.