Larwin:
From the curve, at about 35m, you can see the curve plunging downward with extremely low resistivity. That is typical of a limestone terrain.
The knowledge of geology of the area aided in this interpretation tho.

The geoelectric section explains it further.

So how do you drill in this kind of terrain

We all know what limestone is (some people prefer to call it Calcite), nobody want to be drinking water full with carbonates due to its health effect. So while drilling in this area, it's either the drilling terminate before reaching the limestone layer or you have to drill pass the limestone layer. But in this case, we are drilling pass the limestone layer.

So while drilling, there is need to stabilize the wall of the hole so it won't collapse and also to bring cuttings back to the surface because we don't want limestone contaminating the water. We all know limestone is soluble in water. So in doing this some polymers is added to the drilling mud so as to make it thicker. These polymers serve as stabilizer and prevent the wall of the hole from collapsing down.
After the drilling is completed, these polymers are later remove by pumping water out with great pressure.

This is another reason while you must not patronize quacks or look for cheap borrows. Just consult an organization with great reputation so they can guild you right.

Larwin:
@msogunro, thank you for the compliments. I am so sorry for responding ds late, been busy with projects.

The cost for geophysical investigations varies from place to place and projects, however, our range as a company falls within 20k - 50k. Sometimes we go as far as integrating various geophysical methods in prospecting for our desired interest in the Subsurface. You can inbox me privately for more clarifications or deals.

What is your email address?

What determines the 20k-50k charge? I would like to know the price for this in Ibadan.

msogunro:


What is your email address?

What determines the 20k-50k charge? I would like to know the price for this in Ibadan.

call 08060288869

Hi peeps, permit me to continue with my previous discussion.

We have talked about drilling in a limestone terrain and we have seen a typical curve from the area.

Now let's go to Lagos where we have sand-shale(clay)-sand repeating downward till you meet basement rock.

Here, our target is the sand unit because it's porous and permeable(it doesn't hold water, it allows it to pass freely).

So why do we need geophysical Survey here.... The survey will guide you so as to know the depth you are going and also to pick the best aquifer for your client.

I will post a typical curve from a geophysical survey carried out at Greensrich School, along Ikorodu high school.

here is the result from the depth sounding. You can see the alternation of sand and clay clearly from the curve.
will continue tomorrow to talk more on this. got to rest.

Larwin:
here is the result from the depth sounding. You can see the alternation of sand and clay clearly from the curve.
will continue tomorrow to talk more on this. got to rest.

Cont.



In this area, there has been series of report of collapsing of borehole, so Dextol Global Geophysicals was called in to come and investigate.

From the investigation, we found out that the whole area, has been tapping water from the same aquifer at around 40m(as seen in the curve) thereby imposing so much pressure on the sediments and consequently loosing up and After a short while caving in.

After the investigation, our advice was to go deeper and tap from another aquifer unit which is at 100m or tap from the aquifer at 40m but with good completion.

Nice work here Larwin. I believe people are getting more enlightened.
cc lalastica.

Shegman22:
Nice work here Larwin. I believe people are getting more enlightened.

cc lalastica.

Thanks Shegman22, u mean Lalasticlala

Good job.

cc mynd44

n3xt:
Good job.

cc mynd44

Thanks n3xt

Larwin:


Cont.



In this area, there has been series of report of collapsing of borehole, so Dextol Global Geophysicals was called in to come and investigate.

From the investigation, we found out that the whole area, has been tapping water from the same aquifer at around 40m(as seen in the curve) thereby imposing so much pressure on the sediments and consequently loosing up and After a short while caving in.

After the investigation, our advice was to go deeper and tap from another aquifer unit which is at 100m or tap from the aquifer at 40m but with good completion.

Am so sorry for the slow update. Man is very busy.

Now tapping water at depth of about 100m, I hope you know 150k or 200k might not work here if you really want a good job.

Some ppl will tell you some guys do it for 120k and why is your own high like this.

Some people will even tell you not to bother conducting geophysical Survey.....

Now coming to basement terrain, I will be citing examples from works from Abẹ́òkúta and ibadan.

Will be using Nairalanders' site.... msogunro at Adegbayi area and one other person at Moniya area.

yeah... nice one my guy... tested and trusted

Larwin:
Now coming to basement terrain, I will be citing examples from works from Abẹ́òkúta and ibadan.

Will be using Nairalanders' site.... msogunro at Adegbayi area and one other person at Moniya area.

Looking forward to the discussion.


--

Please do not put up the map with the exact location of my site. Thank you

The curve from the geophysical survey done at Adegbayi area is shown below.

The curve depicts changes in lithology with depth. You can see its very different from the curves obtained from lime stone and sand/shale terrain. This particular one revealed up to five layers. The topmost layer is clay followed by lateritic soil, then we have the weathered basement rock and fractured basement following. An open pit on the site was utilized in getting some of these information.

While drilling this point, we are expected to meet some fractures at 40m and around 80m.

From the images from the pit, we can see some form of sediment layering depicting the geology of the area. Don't let me go in that direction

msogunro:


Looking forward to the discussion.


--

Please do not put up the map with the exact location of my site. Thank you

oh, noted sire!

ollypapi:
yeah... nice one my guy... tested and trusted

thanks boss.

Sorry for being away all ds while, been seriously occupied. If you will like to meet the management staff of Dextol Global Geophysicals, you can connect with us at the on going conference of the Nigerian Association of Petroleum Explorationist at the University of Ìbàdàn.
Thanks.

Larwin:
The curve from the geophysical survey done at Adegbayi area is shown below.

The curve depicts changes in lithology with depth. You can see its very different from the curves obtained from lime stone and sand/shale terrain. This particular one revealed up to five layers. The topmost layer is clay followed by lateritic soil, then we have the weathered basement rock and fractured basement following. An open pit on the site was utilized in getting some of these information.

While drilling this point, we are expected to meet some fractures at 40m and around 80m.

From the images from the pit, we can see some form of sediment layering depicting the geology of the area. Don't let me go in that direction

How much do they charge for this survey? most time people go to site with outdated equipment make fake report, one may be left in cold to deal with the rest.

kopell:
How much do they charge for this survey? most time people go to site with outdated equipment make fake report, one may be left in cold to deal with the rest.

Prices depends on your site location, it normally ranges from 20-50k. In ibadan our corporate charge is BTW 20-25k

There is nothing like outdated equipment sir, we only have improved equipment and the basic principles are always the same. What matters is having the right hand on your project.

About fake reports, thank you for bringing it up, I intentionally ignore it. I am also a victim of it. It's the 3rd party that always cause it. When you work for them, they will collect report and duplicate it so next time they get another project, they simply go to that report and do some editing and give clients without going to field. Even if they to field, they won't pay the Geophysicist because they believe they have a report they can edit for client.

Larwin:


Prices depends on your site location, it normally ranges from 20-50k. In ibadan our corporate charge is BTW 20-25k

There is nothing like outdated equipment sir, we only have improved equipment and the basic principles are always the same. What matters is having the right hand on your project.

About fake reports, thank you for bringing it up, I intentionally ignore it. I am also a victim of it. It's the 3rd party that always cause it. When you work for them, they will collect report and duplicate it so next time they get another project, they simply go to that report and do some editing and give clients without going to field. Even if they to field, they won't pay the Geophysicist because they believe they have a report they can edit for client.

How do you do business without posting your contact information on your page, how do you expect customers to contact you for business?

kopell:
How do you do business without posting your contact information on your page, how do you expect customers to contact you for business?

Smile, thanks for the question... actually this thread was intentionally created to enlighten people after hearing different complains and issues about borehole. many people have already contacted us to help them with there borehole works.

Here is our details...
whatsapp/call 08037010771

We ll be glad to hear from you.

Sorry for nt updating all ds while.... Been seriously busy.

I the above examples on geophysical investigations for water is enough. You should note that the method used is the electrical method. It is very effective and will clearly identify suitable borehole locations for siting the borehole.

As the case may be, other methods Like magnetics, EM may be combine with the electrical method.

You should also know that in prospecting for water, we are not seeing the water... What we see are structures that are likely to house water. That is the interpretation is open to several meaning.

But from experience and knowledge of geology of the area, one can be saved from misinterpretation. This is also part of the reasons why methods are combined.


Picture attached is a typical electrical meter.... Terameter. It goes for not less than 3.5m


Now let me give a short note on drilling.

While drilling, what we aim at is the groundwater which is water found in the pore space of rocks.

As you all know, hydrological cycle also affects this water but to a minimal.

The level below which all the pore spaces in the ground are filled with water is called the water table. The entire region below the water table is called the saturated zone, and water in this saturated zone is called ground water.


An aquifer is an underground formation of permeable rock that can produce useful quantities of water when tapped.

We have consolidated aquifer such as sandstone here the grains/aggregates are connected/cemented to each other.

We also have unconsolidated aquifer such as sand, gravel... Here the grains are loose from each other.

Fractured aquifer... Found in solid rocks. Here water moves through cracks, joints, or fractures.

Unconfined aquifer have no confining rock layers over the top. Water only reaches the level at which the well meets the aquifer.

Confined aquifer... Here the water will rise above the top of the aquifer because of the confining pressure.

This is why the cost of drilling differs. Drilling an unconfined aquifer is quite easier and less expensive. The sediments are mostly unconsolidated and if not done properly can be susceptible to surface contaminants.



To be Cont.

The cost of a borehole depends on these factors... depth and the type of rock we have to drill through

To most people, drilling is getting a machine and putting a hole in the ground which is more than that. It's more
of engineering and science. Once you get the science right, the uncertainties and risk will be greatly reduced. By the way, A driller is only trained at operating rigs and putting hole in the ground and not getting water. Though a team work is required for a successful drilling.

A skilled driller knows how to keep the hole vertical and open till completion is done. His expertise is needed to control the drill pressure and speed as it penetrate different rock types or formations (sand/clay/gravel/granite/quartzite).

In Nigeria, two types of drilling are majorly in use... These are mud(rotary) drilling and air percussion drilling. The difference is in the drilling fluid used which is mud and air.

In Lagos and other sedimentary environment, what we use is the mud fluid while in basement complex we use air. In some situations where the overburden is deep in basement complex air fluid might find it difficult to work.

The functions of the fluid is... To bring cuttings to the surface, to cool and lubricate the drilling bit and also to stabilize the wall of the hole from collapsing. Some additives/polymers are added as the case may be from site to site.

During drilling, logging is done by the scientist to keep track of depth of formation encounter.

After drilling, the hole should be properly cased, grouted and flushed.

The essence of flushing is to bring out any residue cuttings that might block the hole also to make the water clean.

After flushing, installation is done by using an appropriate pump size depending on the yield. If a wrong pump is use, it's going to affect the life span of the hole.

After all this is done, then you can test the water if it is potable and thereafter carry out some treatment.
A properly constructed borehole is normally potable but test like pH, EC, Tds, cation, anion and bacteria should be carried out immediately to confirm if they vary from WHO standards so as to advice on treatment.

Tomorrow, will be showing how water from a hole not properly flushed looks like...

Let me explain how important your money is in getting you the best hole...

1) Site location.... Proximity/distance. Most rigs work with diesel engines, so if your site is farther away from the city Centre then consider paying the company well.

2) Depth to drill...

3) Number of casing to be used

4) The geology of the area... Some people think drilling is much easier in sedimentary terrain than the basement/rocky terrain, the truth is that opposite is the case. Have heard people saying I didn't spent more than 140k for my borehole that was only done out of considerations.... Real drilling in a sedimentary terrain ranges from 1.4m to like 5m. While in the basement you are charged per Metre which ranges from 5k to 6k per Metre.

Now this is where you have to be careful while giving your borehole drilling project out.

First check if the company is competent... We have so many quacks out there and they don't mind the amount you are giving them. A project of 500k, they can ask you to bring 400k or 300k. The after mart of this is poor finishing/completion in a move to save cost... Believe me, you won't want to experience this.

Poor finishing is seen in
1) Casing... Your hole might not be properly cased.... in the case the hole needs to be cased down, it won't be done.

2) Grouting... This should be done properly using granites or gravel. But preferably granites.
This is what leads to surface water contaminating your borehole water. It leads to collapsing of borehole too.

3) Flushing.. After drilling, the hole needs to be flushed to bring out cuttings /dirts which might block the water ways or pump.

4) Most times installations too. Here a substandard pump will be installed for the client.

Here is a properly grouted hole.

If this hole has been flushed properly, the pump won't have to go through the stress of pimping this thick mud water out.... I hope you know it's effect.

The water is getting clearer here