"MWD stands for Measurement While Drilling in the oil & gas industry. The simplest way to describe MWD is to relate it to the measurements a pilot takes. A pilot needs to know the direction they are flying (North, South, East, or West), the angle they are flying at (up, down, or horizontal), and what type of skies they will be flying through (rough, choppy, cloudy, rainy, etc.). Like a pilot a directional driller needs to know these items about the ground formations that they are drilling through. MWD provides this information. Previous to MWD measurements were taken at various parts of the drilling process, but MWD has allowed these measurements to be sent to the surface continuously while the hole is being drilled. This allows for faster drilling, more accurate drilling, and safer drilling.
Beyond the basic concept MWD is a system developed to perform drilling related measurements downhole that are transmit to the surface while drilling a well. MWD tools are installed as part of the bottom hole assembly (BHA) near the drill bit. The tools are either contained inside a thick walled, drill collar (drill collars are typically used to add weight for drilling) or they are built directly into the collars at a factory prior to arriving on the drilling location.
MWD systems can take several measurements such as Gamma Ray, compass direction (shown as azimuth), tool face (the direction that your bit is pointing), borehole pressure, temperature, vibration, shock, torque, etc. The MWD also provides the means of communication for operating rotary steering tools (RSTs).
The measured results are stored in MWD tools and some of the results can be transmitted digitally to surface using mud pulser telemetry through the mud or other advanced technology such as electromagnetic(EM) frequency communications or wired drill pipe."
Directional drilling has been an integral part of the oil and gas industry since the 1920s. While the technology has improved over the years, the concept of directional drilling remains the same: drilling wells at multiple angles, not just vertically, to better reach and produce oil and gas reserves. Additionally, directional drilling allows for multiple wells from the same vertical well bore, minimizing the wells' environmental impact.Improvements in drilling sensors and global positioning technology have helped to make vast improvements in directional drilling technology. Today, the angle of a drillbit is controlled with intense accuracy through real-time technologies, providing the industry with multiple solutions to drilling challenges, increasing efficiency and decreasing costs.Tools utilized in achieving directional drills include whipstocks, bottomhole assembly (BHA) configurations, three-dimensional measuring devices, mud motors and specialized drillbits.
Now, from a single location, various wells can be drilled at myriad angles, tapping reserves miles away and more than a mile below the surface. Many times, a non-vertical well is drilled by simply pointing the drill in the direction it needs to drill. A more complex way of directional drilling utilizes a bend near the bit, as well as a downhole steerable mud motor. In this case, the bend directs the bit in a different direction from the wellbore axis when the entire drillstring is not rotating, which is achieved by pumping drilling fluid through the mud motor. Then, once the angle is reached, the complete drillstring is rotated, including the bend, ensuring the drillbit does not drill in a different direction from the wellbore axis.
One type of directional drilling, horizontal drilling, is used to drastically increase production. Here, a horizontal well is drilled across an oil and gas formation, increasing production by as much as 20 times more than that of its vertical counterpart. Horizontal drilling is any wellbore that exceeds 80 degrees, and it can even include more than a 90-degree angle (drilling upward).