Pipe Sticking Prediction and Avoidance Using Adaptive Fuzzy Logic Modeling

Abstract

Abstract Differential pipe sticking has a major effect on drilling efficiency and well costs. This problem is affected by many parameters, such as drilling fluid properties and the characteristics of the mud cake that is formed while drilling. Comparatively little research has assessed the prediction of stuck pipe. Traditionally, stuck pipe problems are solved by using some standard methods and techniques after they occur, but the real key to savings and success is in the avoidance of the risks associated with the stuck pipe. If these risks are identified in advance, better solutions can be provided to reduce the associated costs. To account for all of the aspects of differential pipe sticking and anticipated nonlinear behavior of the variables involved, fuzzy logic and neural network modeling can be used as primary predictive tools. These methods are widely used in other industries and in the petroleum field, especially in reservoir and core analyses. This paper presents a study of the application of the concepts of fuzzy logic to the problem of differentially stuck pipe. These methods make it possible to estimate the risk of stuck pipe occurrence in the well planning procedure and during drilling in real time. The nonconvolutional analysis of the model is based on the constraints of different drilling variables. Discriminant function analysis and fuzzy logic were used to classify drilling and mud variables. Extensive simulations were performed. This paper presents a case study in which the fuzzy logic and neural network modelling are successfully used to estimate and predict pipe sticking. Introduction Stuck pipe mechanisms are grouped as either mechanical or differential. Differential pipe sticking occurs when a part of the drill string casing or logging tool becomes embedded in a mud solid filter cake and is held there by a significant amount of differential pressure, as shown in Fig. 1. Mechanical pipe sticking occurs while drilling and is identified when the bottomhole assembly (BHA) cannot be rotated or moved because of junk in the hole. The proportion of incidents classified in each category varies with the type of well and the geographical area. Stuck pipe incidents have been one of the major technical challenges of the drilling industry and events typically result in a significant amount of downtime and remedial costs. The recent increase in drilling activity, shortage of experienced personnel and equipment, and drilling in higher-risks areas have increased the risk of stuck pipe events in all drilling operations (Yarim et al. 2007). Fundamental Parameters Affecting Differential Sticking There are many parameters that affect differential sticking. In this study, the general properties of the drilling fluids and mud cake will be reviewed to provide an understanding of how they affect the potential of pipe sticking occurrence and the necessary force to pull the pipe free after it is stuck. Mud Type. A comparison of generic mud types has shown oil-based muds to have the lowest stickance values and gel-waterbased mud has the highest. Polymer-water-based muds fall between these two extremes. It was found that the sticking potential also varies greatly within a mud type, depending on the precise formulation tested (Reid, Meeten, and Way 2000). Lubricant. The addition of certain lubricants for water- and oil-based muds will reduce the effect of differential sticking. If sticking still occurs, then reduce the force needed to free the stuck pipe or tool.