Problem Detection During Tripping Operations in Horizontal and Directional Wells
- J. Venancio Cordoso Jr. (Petrobras) | Eric E. Maidla (State U. of Campinas) | L.S. Idagawa (State U. of Campinas)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- June 1995
- Document Type
- Journal Paper
- 77 - 83
- 1995. Society of Petroleum Engineers
- 1.12.3 Mud logging / Surface Measurements, 1.1.3 Trajectory design, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 1.6.1 Drilling Operation Management, 1.6 Drilling Operations, 1.12.1 Measurement While Drilling, 1.14.1 Casing Design, 4.3.4 Scale, 1.11 Drilling Fluids and Materials, 1.10 Drilling Equipment, 7.6.6 Artificial Intelligence
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Most directional well drilling problems detected in Brazil, and also verbally reported by service companies abroad, occur during tripping operations. A comprehensive research program was undertaken to study this problem. The work is summarized in this paper, and shows the development of a field analysis procedure that proved to be reliable and thus translates into significant cost savings.
The field data was obtained using an in-house mud logging offshore unit and service companies' drilling sensors. The analysis was performed using the new developed method - Two Stage Type Curve Matching: an alert hoook load expert system, followed by a pseudo friction factor "signature" analysis.
Field results showed this to be useful for early borehole detection.
The first concept to be discussed is the "pseudo" mechanical borehole friction factor, represented by the symbol fbp. The traditional concept of mechanical friction factor is related to the physical interaction between two surfaces subjected to a normal force. The word pseudo is used to indicate that the values calculated in the field, are a function of the measured hook load, which in turn is a function of many parameters that include but are not limited to:
Cuttings bed, ledges, partially close boreholes, bridges, hook load sensor error, measured depth sensor error, operational procedures during tripping, pulley friction (within the traveling and crown block), partially stuck pipe due to any other problem not mentioned, drilling fluid properties and effects (e.g.: hydrodynamic friction, buoyancy - considered as a pressure×area effect, etc.), irregular geometry (e.g., washouts), etc. Note: differential sticking is not listed here as it is a static phenomena (addressed in detail, later).
The borehole friction factor has been studied by many researchers,1-6 and used for several applications in directional and horizontal wells. This includes drag and torque predictions and analysis, casing design, trajectory design, and borehole diagnosis. The last - "Borehole Diagnosis" is seen here as a method by which certain drilling problems can be detected at an early stage before they become critical to the operation or well itself.
Single values of the borehole friction factor have been reported and published. The trend analysis, combined with the type curves has so far been limited to our research.
Previous papers have investigated the borehole friction factor by calculating one constant average value. Further investigations by Maidla 7 described the behavior of the friction factor through the use of a medium scale laboratory equipment. This work combines both ideas and goes further to diagnose directional well problems during tripping operations.
The diagnostic procedure is carried out in two stages. First tripping data is collected at a sampling frequence of 3 to 4 Hz (hook load, depth and time). The hook load data is analyzed, on line, and is used to screen out useful data to be used (later defined in the paper), thus eliminating recording too much useless information. Simultaneously to this filtering process, a first check is made against type curves to try and identify some problems: poor borehole cleaning; sections of borehole closure (e.g., Salt Drilling); ledges; key seats; differential sticking; bridges.
The second stage uses the screened data and normalizes it by producing a pseudo friction factor log - the absolute value of fbp is necessary but does not provide any information regarding the type of problem, and most of the times, this value alone is unable to assure problem existence. The total apparent borehole friction factor "signature" is analyzed through another set of different type curves, and tries to identify some of the problems mentioned above.
The objective of this work is to provide a field diagnosis method (supported by fundamental research and appropriate mathematical modeling), that allows the early detection of some problems, known to the drilling industry, while drilling directional and horizontal wells (parts of the analysis is applicable for vertical wells too).
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