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Results
Well Control Procedures in Deep Water
Lage, A.C.V. Martins (Petrobras S.A.) | Nakagawa, E.Y. (Petrobras S.A.) | Cordovil, A.G.D.P. (Petrobras S.A.)
Abstract Well control procedures are revised aiming at the minimization of problems related to kicks and blowouts in deep water operations. The analysis and definition of the most suitable early kick detection methods, well shut-in technique and kick killing procedure are performed to lead us to safer operations. Kick scenarios are defined and studied with the help of a kick simulator to investigate the influence of some parameters and operational practices in the whole well control procedure. The consequences of flow check, hard or soft shut- in, and the driller's or engineer's methods of kick control are discussed to serve as the basis for the definition of the most appropriate techniques to be adopted in deep water drilling operations. Introduction Particularly in the last decade, the oil industry has applied considerable amount of resources in the exploration of new frontiers, such as high pressure and high temperature wells, deep reservoirs, horizontal drilling, slim holes and deep water drilling. The technological effort required in these activities was poorly headed into the development of new devices for early influx detection or more adequate well control procedures, despite of the increased risks of kicks and blowouts in these new environments. Some old well control rules developed in accordance to a different engineering paradigm are still applied. Poor progresses are noticed related to gas influx control procedures despite all the technological advances assimilated by the oil industry. In special, the recent computer breakthrough has spread the application of complex mathematical models as engineering tools, where kick simulators are good examples. In order to revise and modify gas influx control procedures for deep water applications, the influence of some parameters and effects of operational practices are quantified. This approach involves a brief review in kick detection, the definition of kick scenarios and its study with the help of a scientific kick simulator. The additional amount of gas induced by flow check and its consequences are evaluated. The choice between soft and hard shut-in is defined in accordance to a theoretical analysis. A comparison between driller's and engineer's methods is developed to establish the most applicable for controlling a kick.
Experimental Tests for Gas Kick Migration Analysis
Lage, A.C.V. Martins (Petrobras S.A.) | Nakagawa, E.Y. (Petrobras S.A.) | Cordovil, A.G.D.P. (Petrobras S.A.)
Abstract Gas kick migration experiments were performed in a training well for the purpose of analyzing kick behavior under two conditions: open and closed well. The objective was to estimate the migration velocities in each of these situations with no circulation in the well. At present, just the results with air and water mixtures are available. Air and water-base drilling fluids will be used in future experiments. During the tests in closed well conditions, the casing pressure build-up was monitored at surface. Simplified analysis, which do not take into account the system's compressibility, assume that the gas keeps its pressure as it migrates through the well. However, it was observed that the pressure variation was not so severe. A simple method to estimate it was developed considering mud and gas compressibilities and filtrate losses. Practical applications of these results include:availability of more precise values of kick migration velocities and pressure build-up estimation to be adopted by field personnel; support for enhancing kick simulators. Introduction The first part of an experimental investigation on bubble migration velocities during gas kicks was performed in a training well in Taquipe, Brazil. Air and water were used in these initial tests to simulate gas kicks for evaluation of gas migration rates under two distinct conditions: open and closed well. In the near future, other tests will be run using different kinds of water-base drilling fluids. The aim of this project is to obtain gas migration rates and dispersion during static periods of well control procedures. It is expected that this study will contribute to:improve the knowledge of static and dynamic volumetric kill operations; give a better understanding of bubble behavior during shut-off periods in the driller's and engineer's methods; support the development of more accurate gas kick computer simulators. Well Description Well 9-PE-2-TQ-BA (Fig. 1), located in Bahi state, Brazil, was drilled for the purpose of training personnel on well control operations. In spite of not being designed for research activities, its characteristics permit it to be used in such applications. This well is composed of a 13 3/8" casing set at 1310 m and cemented up to the surface. Inside this casing, a 7"×6.366" casing, not cemented, is placed at 1280 m to simulate the wellbore. At the bottom of the 7" casing, a 1.9" (1.5" ID) tubing is used to allow for air or gas injection (line A in Fig. 1). There is still another 1.9" (1.5" ID) line used to simulate circulation losses conditions (line B) at 800 m. For the present tests, a 3.5" tubing string was run into the well with pressure sensors located at the positions shown in Fig. 2. Other well geometry characteristics are summarized in Table 1.
- Well Drilling > Pressure Management > Well control (1.00)
- Well Drilling > Drilling Fluids and Materials (1.00)