The Past and Present Life of MWD in Directional Drilling
Original Title [Dry Goods Super Long Article] The bra tape measure Past and Present Life of MWD in Directional Drilling 1 Basic concepts 1 What is MWD instrument MWD is the abbreviation of Measurement While Drilling MWD instrument is an important member of the whole measuring instrument family 2 What does the measuring instrument measure The data obtained by the measuring instrument are the well deviation azimuth and tool face of the instrument near the current downhole bit What do these parameters mean For example these data can now be measured by ordinary mobile phones A Well deviation (horizontal and vertical angle) is equivalent to measuring the horizontal and vertical state of the mobile phone and the horizontal or vertical screen will be given on the mobile phone B The direction (north south east and west) is equivalent to the compass of the mobile phone C The tool surface of the instrument (how to turn the head up down left and right) is equivalent to some “720-degree panoramic websites” of the mobile phone and the scene picture can be updated with the rotation of the mobile phone Expand the full text Measuring instrument integrates well deviation azimuth tool face and other measurements but at the beginning of the DHD Drill bit invention of this kind of instrument more than 100 years ago it mainly focused on well deviation data so many people in China’s petroleum circle still call it “inclinometer” 3 Why measure Drilling is like walking there must be a turn to reach the end walking with eyes open to observe which intersection turns Drilling also needs to control the drill bit to drill to the target point and the measuring instrument is the so-called eye Tell me where it is and where the target is As an example in the figure below a directional well needs to meander several kilometers underground to reach the target point of the oil layer under the guidance of the survey instrument 4 What is measurement while drilling The meaning of while drilling is relative to the traditional stop drilling It is different from the wireline logging instrument or other instruments to obtain data at the cost of “stopping drilling” and then running in the measuring instrument The method of stopping drilling at intervals is equivalent to walking a few steps with your eyes closed stopping and opening your eyes to see where it is If there is drilling technology we can get real-time downhole data and know the specific location when drilling It’s like walking with your eyes open 5 Why measure while drilling A First of all it will take time and money to stop drilling Once the drilling is stopped for measurement it will take at least 4-6 hours and more than 8-10 hours If it is operated at sea this period of operation may cost hundreds of thousands to millions of dollars per day B Pure blind drilling without the guidance of measurement data may lead to deviation from the target point resulting in borehole collision and other risks C When measuring the drill pipe is still which causes the collapse of the well wall and the sticking of the drill pipe Therefore MWD overcomes the disadvantages of “stop drilling” measurement The downhole data can be obtained in real time when drilling and the specific location can be known In addition to the high price the measurement while drilling is better than the “stop drilling” measurement method in other aspects 6 How to realize “real-time data” while drilling The downhole instrument has no cable to connect with the surface instrument That requires a coded transmitter for downhole instruments a receiver at the surface and a set of decoding programs There are generally two ways to realize the coding transmitter of downhole tools A Drilling fluid pulse It is equivalent to putting the hand in the water flow under the faucet twisting the knob of the faucet and the impact pressure on the hand will change The downhole instrument limits the flow of drilling fluid through an electronic mechanical switch and transmits data in a certain frequency sequence and the ground sensor will sense the pressure change and demodulate the signal And B wireless electromagnetic pulse wherein that downhole instrument transmit a radio signal pulse There is a wireless receiver on the ground to receive the wireless signal MWD a modern measurement while drilling instrument is evolved step by step from the predecessors of “stop drilling measurement” Let’s straighten out MWD and its predecessors 2 The History of the Family of Measuring Instruments At the very beginning the measuring instrument may only be used to measure where the well is finally drilled If there is no instrument that can control the trajectory it can only be known but not controlled and its role is limited Therefore the development of measuring instruments is closely related to the development of trajectory oriented control instruments
