Abstract
ABSTRACT The solubility of methane in an invert emulsion drilling fluid has been measured up to 15000 psi [103.42 MPa] and 350F [177 C]. Resulting data describing the effects of temperature and pressure on mixture density and phase behaviour havebeen incorporated into a computer model to determine wellbore responses at surface and downhole. The model contains algorithms to model the transport of dissolved gas by dispersionand free gas by bubble rise in addition to models for fluid flow. The model is capable of simulating both controlled anduncontrolled kicks in invert emulsion drilling fluids. Gas behaviour in water based drilling fluids can also be evaluated. Surface responses including pit gain, annular flowrate and choke pressures have been simulated. It has previously been suggested that gas kicks in deep high pressure wells and oil based drilling fluids are more hazardous than in water-based fluids because of the solubilityof hydrocarbon gas in the oil phase of the mud; the gas in solution producing only a fraction of the expected pit gain at surface. However, results from the current model indicate that when a kick is taken in a deep high pressure well the observations of pit gain at surface can be similar for both oil- and water-based muds.
Published Version
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