In short, no. The energy imbalance of the earth is estimated at +0.71 ± 0.10 W/m² (positive indicating a net gain).

Meanwhile, the mean heat flow through the crust is approximately 0.092 W/m² , or roughly the uncertainty in the first measurement (and an order of magnitude less than the total imbalance). Even if all of that heat flow through the surface was a result of the removal of an insulating layer within the crust, the result does not come anywhere close to the total imbalance. In addition, oil does not form an insulating layer within the crust. Oil does not form a layer under the surface rock, and is not even present in large underground oceans within the crust. Rather, it fills pores in the rock, sort of like a sponge. This means that there isn't really a "layer" of oil that could be insulating.

Also, the thermal conductivity of oil (~0.12-0.13 W/(m-K)) is much lower than that of the surrounding rock (various rocks from this table, typically ~1+ W/(m-K)) . Thus, most of the heat flow is through the surrounding rock already, and removing the oil would not have much effect. A further consideration is the fraction of the crust which is/was made of oil. An estimate of the total CO₂ produced by humans and industrialization (since 1751) is around 1.5*10¹² tons. Due to the exchange of hydrogen for oxygen/breaking of multiple bonds/approximating as gasoline/etc. to go from the hydrocarbons in oil to CO₂, this corresponds to roughly 3 x the mass of oil taken out of the crust (so: mass of oil ~= 0.5*10¹² tons). Compare that with the estimated mass of the crust of ~3*10¹⁹ tons, and we see that the fraction of the crust that was oil is entirely insignificant.

It has been estimated that humans have used about one trillion barrels of oil since commercial oil drilling began. A barrel of oil is defined as 42 gallons, or 0.16 cubic meters, so the total volume of oil that has been consumed is approximately 160 billion cubic meters, or 160 cubic kilometers (for comparison, the volume of Lake Michigan is approximately 4,900 cubic kilometers). If all the oil taken from the earth were deposited on the earth’s surface, it would make a layer of oil about 0.3 millimeters tall, or about 20 billion times thinner than the radius of the earth. If you were wearing a jacket that was 20 billion times thinner than you are wide, it would be about the thickness of a single atom. So, the influence of the insulation of the oil that we have removed is negligible at changing the temperature distribution within the earth.

No. The Earth's core spreads heat through conduction and convection, and oil does not stop conduction and actually helps convection.

Global warming is more likely due to the fact that carbon dioxide acts as a greenhouse gas in the Earth's atmosphere. Sunlight is mostly blue, green, and yellow, colors of light that can pass through the atmosphere. When this light reaches the Earth's surface and oceans, it is absorbed and becomes heat. The Earth then radiates that heat away in the form of infrared light, a color too red for your eyes to see but is still a color of light. Certain gasses, notably carbon dioxide and water vapor, do not allow infrared to pass through them. Thus, the infrared light gets trapped inside of the atmosphere. As a result, the earth is getting warmed up by the sun but can't get rid of its energy as easily, which means that the temperature goes up.

There are other possibilities for what might be causing global warming, and some of them are natural. It is likely for example that the sun has become slightly brighter in the last hundred and fifty years, and this would warm the Earth up too because it means that there is more light that gets absorbed in the first place. The effect that humans are having that is warming up the planet, however, comes from burning chemicals that contain carbon (oil being one of them), which releases carbon dioxide into the atmosphere.

It is the combustion of oil to produce CO₂ gas that causes global warming. CO₂ is a gas that does not allow Infrared Radiation (IR) from the earth's surface to go back into space. Instead CO₂ molecules absorb the IR photons that are emitted from the earth’s surface… and that warms the atmosphere.

Heat from the INTERIOR of Earth does not warm the atmosphere … the heat flowing from deep in Earth is very, very, very small.

Global warming comes from us burning the oil and other fossil fuels in the earth, and from burning wood. This Wikipedia link gives 4 causes.

Here's an article about how hot the earth's core is: here

It doesn't say anything about global warming. There're lots of rocky layers between earth's hot core and us. Also, if oil removal directly caused global warming, don't you think the surface of the earth would be sinking down from all the oil lost?