A relationship to estimate the optimal drilling mud pressure in oil wells in carbonate formations of southern Iran oil fields

Document Type : Research Article


Imam Khomeini international university


The analysis and prediction of well wall stability is considered as one of the most important and critical points in drilling operations. The instability of the well wall is one of the most serious problems in the oil and gas well drilling industry because it can lead to loss of part of the well or its entirety, which ultimately results in delays in operations, increased costs Drilling and delay will occur at the time of operation. One of the most important ways to cope with this problem is to determine the optimal drilling mud pressure. The pressure of the mud should be so high that it is in proportion to the amount of tension in the pores and pockets, and to the extent that the well after the large tensile fractures caused by the high pressure of the mud, as well as the shear fractures due to low pressure It will be safe. The aim of this study was to obtain a relationship to estimate the optimal drilling mud pressure in wells in the oil-rich regions of southern Iran. To achieve this goal, information of a number of oil wells was collected in the oil fields of southern Iran and then, using FLAC2D software, a limited-scale numerical program limited to oil wells, oil wells were analyzed in two Equilibriums and equilibriums modes have been investigated. Ultimately, for determination of the stability of the optimum drilling mud in the elastoplastic method, the method of determining the normalized level of NYZA has been used. In each step, optimal drilling mud pressure is calculated and finally, a correlation is presented using SPSS software through multivariate linear regression. This relationship is a linear relationship in which the optimal drilling mud pressure is estimated by parameters of minimum and maximum horizontal tensions, pore pressure, internal friction angle and cohesion.


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