Lost circulation is the loss of borehole mud to the exposed formations in the well and is one of the most common problems of oil well drilling. Mud flowing into the formation implies that there is less mud return at the flow line than is being pumped or that there is no return at all. …
In general, there are two main causes of lost circulation in drilling operations problems which are as follows: As this article is one of five articles to cover the loss of circulation problems, I recommend visiting these links for a better understanding: Causes of lost of circulation In Drilling A) Invasion In many cases, lost …
Pumping a drilling fluid requires overcoming frictional drag forces from fluid layers and solids particles. In this article, we will explain the pressure loss calculation steps in the drill string. The pump pressure (Pp) can be described as the summation of the frictional forces in the circulation system: PP = PDS + PB + PA …
Introduction To Mud Contamination By CO2 Carbon dioxide (CO2) is a common constituent of natural gases and is present in most types of formation fluids. Carbon dioxide dissolves in water, forming carbonic acid that lowers the pH. This lowers the alkalinity of water based muds changing hydroxyl ions (OH–) to bicarbonates (HCO3–) and carbonates (CO3-2) …
About 60% of oil well footage is drilled in clays and shales. These rocks are neither hard nor abrasive and, thus, should be easy to drill. Problems arise, however, because of the soft and sticky nature of the cuttings produced. These cuttings absorb water from the drilling fluid, swell, and stick to the Drilling Bit. Balling …
When weighted muds are used in highly deviated wells, there is the tendency for barite to settle towards the low side of the hole, creating a stratification of lighter mud on top and heavier mud on the bottom. The heavier layer then begins to migrate downwards along the length of the hole due to the …
Barite plug use is usually limited to extreme or emergency conditions where it is imperative that some measures be taken to seal off the bottom section of the wellbore. This type of plug is applicable in several situations, including: Objectives of Setting Barite Plugs A Barite plug is a barite slurry pumped down the drill …
Usually, Mud Engineers design drilling mud to be able to carry out mud basic functions. Thus, As the concentration of Cement contamination increases in a drilling mud system, there will be a detrimental effect on its performance. In general, we can define the contaminant as any material that causes undesirable changes in drilling fluid rheology …
Calcium sulfate occurs in nature as Gypsum (CaSO4 l H2O) or Anhydrite (CaSO4 ). It is found in thick sections, stringers, in make-up water, embedded in silts as in evaporite formations and sometimes in the caprock of a salt dome. Causes of Anhydrite/Gypsum Contamination Calcium sulfate causes aggregation and flocculation of a fresh water mud, …
Flow Regimes are the behavior of the fluid while flowing in a well. The most common regimes are laminar, turbulent, and transitional. Unfortunately, it is impossible to define each type in the well clearly. For example, mudflow may be predominantly laminar, although the flow near the pipe waIls during pipe rotation may be turbulent. Laminar …