There are many segments that attribute to the Oil and Gas sector to keep things running. Measurement, while the drilling segment is one of that segment which helps in identifying the actual direction of well, bore that in turn helps in hitting the downhole reservoir in the right direction. The duty of MWD (Measurement while drilling engineer) is therefore very critical.
The purpose of this paper is to identify the duties and responsibilities of MWD and how the use of this technology helps in bringing the success of wellbore.
Lead MWD's purpose on the rig site is to lead the team of engineers to execute measurement jobs. Initiating from programming the measurement tools, Making Up the tools on the rig floor, performing designated Shallow tests, preparing surface systems, generating the Logs till delivering the final reports to client covers under MWD responsibility.
The overall project objective was to drill the 8.5’’ section of a horizontal well while taking on the Logs to determine the formation specs as well as formation tops of the section drilled. MWD's main objective was to land the well accurately to the horizontal section keep on generating the Logs to provide the client Real-time scenario of what we are drilling.
A statement of MWD duties:
MWD main duties and tasks were as following:
I with the MWD team arrived on the rig site location. The client company was holding well rights, the operator company was hired for Rig Operation and we were the member of Service Company to execute and supervise the Measurement while drilling as well as Logging operation on rig site. We came a day prior to the start of a job to prepare every required element for job execution. (The names of the companies are withheld due to confidentiality concerns)
The designated part of the job is to drill the 8.5’’ section and land the well to 90 deg at the direction of 170 deg from the North. In this phase, client gave MWD his requirement as per the services they require while drilling. It includes Inclination and Azimuth services as measured by Measurement while Drilling tool and gamma-ray Logs.
After verifying the serial numbers of tools MWD checked their calibration report in order to ensure that the readings they provide should be correct. Here the tool consideration is a positive pulse tool. This tool consists of Accelerometer (to measure Inclination), Magnetometer (to measure Azimuth/Direction) and Gamma-ray sensors which concludes in its Electronics as well as Pulser in order to send encoded data through mud (while drilling) to surface to decode and a small Turbine which converts mechanical energy of mudflow into electrical energy for the Electronics to work within the tool which helps in No Lithium battery use while downhole. The sensor in the tool to identify gamma-ray is Scintillation Detector which consists of a Crystal Scintillator, a photomultiplier tube, and a discriminator circuit.
On the day to initiate the job, MWD runs the positive pulse tool package with complete rig’s Bottom Hole Assembly to 8506 ft. The 9 5/8’’ casing shoe was at 8569ft. When the rig site mud pumps started and approached at 480gpm, signal through sensors came to surface via mud telemetry and further decoded in specific computer software present in the logging unit. MWD started taking the gamma-ray logs while Wipe Down till 8590ft where the last 21ft was the rat hole. From there as per Directional Drilling Engineer instructions we started drilling. MWD keeps on tracking the depth at every connection as well as taking the Survey which gives Inclination and Azimuth at Stand down depth. Gamma-ray logs keep on building finely and MWD keeps on sending the logs online to Client and makes Back Up file always updated. The rate of penetration of drilling remains in between 10-15 ft/hr. Directional Drilling Engineer keeps on penetrating the well in right direction and MWD kept on building Real-time Gamma-ray logs as well as directional data and providing them to a client. They continued on drilling till 13450ft where the client decided to TD (Total depth) the section. Gamma-ray log provided to the client was up to 13410ft having a scale of 0-150 Gapi. The wellbore was smooth and clear, hence started pulling out of a hole to surface.
While on surface MWD Lay down my tool and dump the data recorded in it to verify two things. Firstly, QC the tool to check if the amount of lateral and axial shocks as well as vibration, stick and slip values were within their confined ranges and secondly to compare the recorded mode gamma-ray log with real-time gamma-ray logs. While the QC tool, it was in good specs and both gamma-ray logs overlap each other indicating their correct behavior. MWD handed over the logs to a client, rig down all of my sensors on the rig floor, store them in Logging Unit Workshop and backload all of the tools to service company yard for inspection.
Due to the data provided by MWD, Client Company can be able to steer the well in the right direction which saved them millions of dollars as they hit the reservoir incorrect direction. This allows in the increment of Oil and Gas production rates. The logs helped the client indicating proper downhole formation characteristics which in turn helps in further developing the field.
What I observed in my research is the professional attitude demonstrated by a segment of Service Company which with the help of research and technology helps in saving time, money, resources of Client Company. MWD job carries a lot of responsibility and deliverability charges are quite expensive but it’s nothing when compared to the profitability it provided to the client.
Mian M.A., “Petroleum Engineering Handbook For The Practicing Engineer, Vol.II, PennWell Publishing, Tulas Oklahoma.
Dippl and Prassel, Drilling Engineering, Curtin University of Technolgy, Vol i.
Source: This is a full version of an article by our student Mohammad Hassaan Khan, supervised by our lecturer Prof. Vladimir Biruk.