What is an appraisal well?
Why drill an appraisal well?
An appraisal well will give us detailed information about the geology and groundwater in the area. The main objective of the well is to confirm the thickness of the sand layer. In addition, we will measure the physical and mechanical properties (the dynamic response) of the formation and collect sample materials from different depths so that we can make a detailed description of the geological conditions in the area. We hope to be able to drill down to 325 meters.
In the drilling process we will use drilling mud. This is water mixed with bentonite and barite. Bentonite is a common clay mineral which we add to the water to make it viscous. Barite (BaSO4) is a mineral with high density which is soluble in water. It is added to the water to make it heavier and enabling the possibility to create over pressure in the well. This drilling mud is pumped into the hole during drilling. The water will penetrate into the sediments while the bentonite will stick to the sand grains and make up an impermeable mud cake between the well and the formation. This mud cake is important to stop the well from collapsing. Before we insert pipes into the well, it will be logged with sensors measuring the dynamic properties of the formation. These properties are sound velocity, electrical conductivity and the ratio between clay and sand, in addition to the diameter and the shape of the hole. As we drill, we will enter the saturated zone. We will take water samples and look at the chemical composition of the water. These results can later be used as a background level if we start to inject CO2. The well might be used as an injection or monitoring well later in the project.