APPLICATION OF MINIMUM CURVATURE METHOD TO WELLPATH CALCULATIONS
A major drawback of directional and horizontal well drilling is the numerous complex computations required to be done while planning a well. These computations are very stressful and time consuming especially when done manually. One of the objectives of this study was to develop a user friendly Excel Spreadsheet program that would make the computations of these well trajectory parameters easier, faster and accurate. An Excel Spreadsheet program was developed employing the Minimum Curvature method (and for other five methods) for wellpath design and planning. This would help increase the usage of these trajectory methods especially the Minimum Curvature method. The program is able to provide pictorial views both in the vertical and horizontal plane of the trajectory of the drilling bit’s position in the wellbore. This would therefore help to minimize risk and uncertainty surrounding hitting predetermined target. This is possible because deviations can easily be detected and the necessary directional corrections or adjustment be initiated to re-orient the drilling bit to the right course before (planning process) and during the drilling operations.
FORMULATION OF THE PROBLEM
Directional drilling is the science and art of deviating a wellbore along a planned course to a subsurface target whose location is a given lateral distance and direction from the vertical (Bourgoyne et al, 1991). Directional drilling and horizontal wells represent an efficient way to achieve or hitting special targets that may or are very difficult to reach using vertical wells (Tarek, 2000). Directional drilling is relatively done to increase production rates, control water and gas conning, control sand production and increase recovery rate (Bourgoyne et al, 1991). There are many reservoirs which can not be tapped by vertical wells or would be uneconomical to exploit with vertical wells (Bourgoyne et al, 1991). Other reservoirs are also characterized by vertical permeability or the pay zones may be very thin and producing with vertical wells would require quiet a number of them which would make vertical wells to be very uneconomical in such situations. The application of vertical wells in such formations could also result in lower ultimate recovery (Tarek, 2000). In such low permeability formations, the only way out is to use directional and horizontal well technology which has over the years proved to enhance ultimate recovery (Bourgoyne et al, 1991). Due to the more economical nature of directional and horizontal wells over vertical wells in most cases, they are mostly the preferred technology in offshore drilling technology (Bourgoyne et al, 1991).
1.2 Problem Definition
A major drawback of directional and horizontal well drilling is the numerous complex computations required to be done ahead of time before drilling resumes and also during drilling operations (Sawaryn, 2005). These computations become very stressful and more complex when done manually. The programs available in the market used for these computations are usually very expensive to acquire, but the development of a user-friendly Excel Spreadsheet program which employs the Minimum Curvature method for wellpath planning would help minimize the stress and time in executing these complex computations. More importantly, an Excel Spreadsheet program is very flexible and can easily be modified or updated at any point in time to meet the needs of the industry. This study seeks to use the Minimum Curvature Method to design well path using Excel Spreadsheet to determine the optimum well path parameters. This would help reduce risks and uncertainty or prevent deviation from target, minimise non-productive time and reduce drilling cost. This would therefore enhance planning process and maximizing return on investment.
1.3 Objectives of Study
The objectives of this study are:
1. To develop a user friendly Excel Spreadsheet program that will make the computations of well trajectory parameters easier, faster and accurate.
2. Use the Excel Spreadsheet program to evaluate and compare some of the survey calculation method available for the industry.