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Naturally Fractured Reservoir is a term that we use to the reservoir that  the fracture have significant contribut ion to the change of the reservoir's permeability.With these fractures, there are others properties which will change too, such as flow rates, anisotropy, recovery, and storage.  It is a kind of confusing material for many people, as until this day, people always prefer the conventional reservoirs which have been been developed and observed for hundred years. People simply don't know the fact that more than 50% of proven reserve in the world are obtained in Naturally fractured reservoir. Even almost all the geothermal reservoirs are naturally fractured reservoirs. Yes they are more complex and heterogeneous, but as the world need energy to develop the modern civilization, the advancement of technology to the more complex and multiple porosity reservoirs is a must. That is why our future will move towards the development of this fractured reservoir. While ot...

What is Drilling Mud? Drilling Mud/ Drilling fluid is very important in drilling a well. If you’ve ever drilled a hole through a wood, you must have known that the wood chips should crash & fly outside the hole, or the bit will be buried with the wood chips (That is why people occasionally blow the hole to crash out the buried wood chip). How do people maintain those “chips” get out the well while drilling in the oil field, in the condition that the bottom hole might be kilometers away from the surface? Yes, this is the purpose of the drilling mud itself. We need to put the mud inside the hole, then circulating the mud while drilling to transport those “chips” (which is called ‘cuttings’ in petroleum engineering terminology) out from the hole. 

Core Core sampling is very important to be done to know the petrophysical property of the formation. It is usually shaped as a cylinder, since it is obtained by using coring bit, the drilling bit which drills the formation with a hole in the center to obtain the sample while drilling, which is called the "core bowling". The cost for coring a well is very expensive, and not all wells will be cored. Also, instead using the conventional whole core, people may also use the sidewall cores, which will take the samples from the wall after the well has been drilled by using wireline. Sidewall cores are cheaper than the conventional core explained above, but the data will not be as complete as conventional core. The advantage is the price and the time which is only spends hours, instead of days. The sidewall cores are retrieved by two ways: Rotary sidewall coring and percussion side wall coring. Rotary sidewall coring will use a special small core bit which will poop o...

Before talking about mud engineering, we should understand first the importance of the mud itself in drilling a well. These functions are remove cuttings from well, suspend and release cuttings, control formation pressures, seal permeable formations, maintain wellbore stability, minimizing formation damage, cool, lubricate, and support the bit and drilling assembly, transmit hydraulic energy to tools and bit, ensure adequate formation evaluation, control corrosion (in acceptable level), facilitate cementing and completion, and minimize impact on environment One of the most significant uses of mud is based on its weight (density). This is mainly related to the function of controlling formation pressure and removing cutting from the well. The mud weight should be adjusted in time and precisely to ensure the mud does its functions. When the mud weight exceeds the fracture pressure (the maximum pressure the formation can accept before it breaks), the formation may fracture and lost c...

Renewable energy is an interesting thing to be considered as working field in near future. This energy source is still undervalued, and it can be analyzed that the performance will be "BULLISH" (as what the stock traders say) in about 10 years. But why renewable energy is that important? First, a consideration of people to convert to renewable energy is about its sustainability and cleanness. Renewable energy will be sustain longer than fossil energy, and also less harm to the environment. As it can be seen, on the long term issue, renewable energy should has been the major source of energy. But back to the basic, all these energy sources are used to get profit, and this was the main disadvantage of renewable energy. Petroleum industry is more profitable than the renewable energy. It seems that the renewable energy still need some years to be considered. Moreover, there are some step before renewable energy to be considered after petroleum industry, named unconventional...

In this article, we will discuss the graph above, whose Y axis displays pressure and X axis displays distance from well.   Rw represents the radius of the well , Re represents the distance of the reservoir limit from our well, while Rs is the distance of the skin zone from the well. The picture explains about the skin zone which is located near the well, created as the result from damages of our interventions to the formation. This skin zone will give vast amount of problems, as in the picture, the pressure will alter to be smaller near the well. But, the skin itself does not always make the pressure become lower. The skin also may be engineered to make the permeability near the wellbore become even higher than the natural permeability, thus increase the pressure higher than what supposed to be naturally. That might be the method to solve the problem which may be seen from the picture, as the higher pressure near the well will be advantageous for us. But first, let’s...

Picture source: Permadi,A.K.2004.Diktat Teknik Reservoir 1.Bandung This picture shows the isopach map , a map which is used in original hydrocarbon in place calculation, namely volumetric estimation . Original hydrocarbon in place is the hydrocarbon which is stored in reservoir prior to production. By this definition, the hydrocarbon in place will not show how much volume of hydrocarbon we may obtain from the formation. Although the original hydrocarbon in place does not show how much we can gain, There is thing called Recovery Factor , a percentage range about how much hydrocarbon we might obtain typically, whose value depend on the drive mechanism of the reservoir and the reservoir fluid type. We will see why isopach map is important here, in volumetric reserve calculation. The volumetric method is a method to count the volume of hydrocarbon from geological, log, or core data . This is a good estimation method before the production data can be achieved. This method i...

Binary cycle of geothermal plant is a very fascinating geothermal engineering which utilize the geothermal energy to the extent of zero withdrawal from underground. It is a kind of method which might be dreamed by people concerning the environmental issues, such as pollution, spill, and perhaps, the answer for renewable energy . Indeed, the geothermal energy itself is a clean energy that should be developed, but one special feature of the binary cycle is that the temperature of water in the reservoir doesn’t need to be as high as usual geothermal energy. Most of the time, the power plant for geothermal energy will need steam with temperature of 200 deg C, but by using this scheme, the reservoir fluid will only need as hot as 100-200 deg C . Among other renewable energy that can be used, perhaps geothermal energy should be considered more since the efficiency and technical knowledge are simply modifications of the system of petroleum production.  Looking at the picture ...

This post is an elaboration of the  "Basic Logging Interpretation" slide  which I share in my previous post  [CLICK HERE ] . This explanation will  fit the best if you want to present the  " Basic Logging Interpretation"  slide  at page 7 It is very important to understand that the resistivity log which has high resistivity measurement doesn't always detect the hydrocarbon containing zone. There are two possibilities: first, the low resistivity zone might contain low resistivity fluid, which is hydrocarbon, and if that is the case, we have found our sweet pay zone. But second, the formation might be very small in porosity that the resistivity measurement becomes low. Most of the rock is nonconductive to the electricity, so when the porosity of the rock is very small, there will only small quantity of fluid in the rock. Even when the fluid is very conductive, since the quantity is small, the log will show low resistivity measurement. That i...

This post is an elaboration of the  "Basic Logging Interpretation" slide  which I share in my previous post  [CLICK HERE ] . This explanation will  fit the best if you want to present the  " Basic Logging Interpretation"  slide  at page 6 Basic: Why the Logging Results Should Show The Permeability? Because the permeability of the rock represent the capacity of the rock to flow the fluid through it, it is very common that a wellbore be checked by logging tools to measure the permeability of some interesting place of the zone. For more detailed technical and scientific information about permeability, see my previous post here . So since a low permeability rock will hardly flow fluid through them and high permeability rock will flow fluid easily, people will check the logging result whether they can find high permeability zone with low resistivity. So, People Will Look For High Permeability Zone Which Contains Hydrocarbon! ...

This post is an elaboration of the  "Basic Logging Interpretation" slide  which I share in my previous post  [CLICK HERE ] . This explanation will  fit the best if you want to present the  " Basic Logging Interpretation"  slide  at page 4   Well logging is an important job in Oil and Gas industry.  It uses sophisticated tools, equipments, devices and software, The interpretation will be done by professional earth scientists with precision as it is very important in formation evaluation. That is why there are many trainings, seminars and handbooks of well logging, which are reasonably high in price, to make sure people contributing in well logging jobs are capable in using the software and basic procedure to get the representative results of the formation. The slide ppt (ppsx) of basic interpretation in well log results has been shown in this blog, but to elaborate it, we should know the tools, procedures, and simple facts in t...

Introduction Logging is one powerful method to measure physical properties of the formation around borehole to make sure whether we are lucky enough to drill through petroleum bearing zone!   Logging is done by lowering a logging tool into the borehole and recording formation properties while the tools are rolled up to the surface. These logging tools can be divided into broad categories based on the physical properties measured. The tools use variety of sensors to measure different properties such as gamma ray, electrical, acoustic, radioactive responses, electromagnetic, pressure and other properties of the formation rock and fluid. Since the tools are rolled up to the surface while recording the data, the record could be seen continuously as a function of depth. These data will represent a lot of formation properties depend on what properties are the tools measure from the borehole. These data then should be interpreted to get its main goal: to know the condition of t...

This post is an elaboration of the  "Mud Invasion Profile" slide  which I share in my previous post  [CLICK HERE ] . This explanation will  fit the best if you want to present the  "Mud Invasion Profile" slide  at page 4 What is Resistivity? Before going further to resistivity, we should know what resistance is first. Resistance can be defined as voltage divided by the current. The concept of resistance is parallel to the concept of  ”friction” in mechanical. It defines how hard electric current can pass. The Ohm's Law states that ideally the ratio of voltage and current are always constant. That’s why it is believed that the resistance depends on material and condition being used to flow the current. Unlike density, which will not change as the material is cut, resistance will change if the material’s geometry or volume changes. That is why more than just the material, the geometrical properties also affect the resistance. After w...