A Multidisciplined Approach to Designing Targets for Horizontal Wells
- S.T. Solomon (Conoco Inc.) | K.C. Ross (Conoco Inc.) | R.C. Burton (Conoco Inc.) | J.E. Wellborn (Conoco Inc.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- February 1994
- Document Type
- Journal Paper
- 143 - 149
- 1994. Society of Petroleum Engineers
- 1.10 Drilling Equipment, 5.5 Reservoir Simulation, 1.12.1 Measurement While Drilling, 2.4.3 Sand/Solids Control, 4.1.5 Processing Equipment, 5.5.5 Evaluation of uncertainties, 5.1.7 Seismic Processing and Interpretation, 1.6.6 Directional Drilling, 5.1.2 Faults and Fracture Characterisation, 4.1.2 Separation and Treating, 1.6.1 Drilling Operation Management, 1.6 Drilling Operations, 1.1 Well Planning, 4.3.4 Scale
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A multidisciplined approach to developing 3D target diagrams and their associated tolerances provides a cost-effective method for designing horizontal wells. The key to this approach is that the diagram quantifies and communicates the uncertainty of the target boundary conditions to others involved in designing and drilling a well. Field examples show how a multidisciplined team creates a 3D target diagram. The preliminary 3D diagram is used to examine the combined uncertainty in the position of the features constraining the target. To maximize the target size, the team must decide on the relative importance of each constraining feature and assign target tolerance limits. The final target diagram minimizes both risk and cost to produce the optimum well design.
With horizontal drilling equipment and technology improvements, efforts are now being directed toward optimizing the horizontal drilling process by lowering costs. Planning is widely acknowledged as the key to success in any horizontal drilling project; however, the importance of target design in well planning is not always as well recognized.
Targets for horizontal wells are by necessity 3D. Initially, this concept was a challenge to an industry more familiar with using 2D geometric figures to design vertical or conventional directional well targets. For the first horizontal wells, the simple 2D geometric target shape became a 3D "box." Drilling engineers discovered that these simplistic well targets were inadequate and caused severe problems during drilling be cause they fail to address geological and reservoir uncertainties. Targets were often missed entirely when the formation top of a thin zone "came in" too high or too low. Drilling personnel discovered very quickly how inefficient and expensive it was to "chase" a horizontal target that dipped away. Experiences like these prompted interdisciplinary discussion. Drilling engineers sought to become more informed on the geological aspects of the horizontal prospect. In response, geoscientists found that they needed more information on the horizontal drilling process. It was soon (re)discovered that a well's success was directly related to the amount and quality of information shared among the different people responsible for the drilling project. It was also found that this information and its reliability could be communicated best through pictures by a 3D well target diagram.
This paper discusses the multidisciplined process of designing 3D horizontal well diagrams and provides field examples of their use. The importance of communicating the uncertainty of each target constraint between disciplines is emphasized as the key to cost-effective target design.
|File Size||2 MB||Number of Pages||7|