Abstract: The present invention relates to a method and to a fluid for drilling or workover in a well running through a porous permeable formation, wherein a water-based well fluid circulates in said well. In the method, at most 3% by weight of a composition obtained from fat, or an oil, and an alcohol, is added to the fluid in addition to the conventional constituents for such a fluid, the chain lengths of the acid and alcohol parts being chosen such that the ester thus obtained has sufficient dispersion in water, compatibility with said constituents, does not form an emulsion with the reservoir oil and adsorbs sufficiently on the porous formation.

Abstract: A method and device evaluate simultaneously, with the same equipment, physical parameters such as the absolute permeability and the porosity of fragments taken from a fragmented natural or artificial porous medium. The porosity of the fragments is measured by means of helium pressure tests according to a protocol known in the art. The chamber (1) containing the fragments is communicated with a tank (11) whose volume is also known and containing helium at a known pressure. At pressure balance, the value of the solid volume can be deduced. The rock envelope volume and the fragments mass are also measured. Combining these measurements allows to determine the porosity of the samples and the density of the rock. Their permeability is then measured by immersing them in a viscous fluid and by communicating the chamber with viscous fluid at a determined pressure contained in a vessel (9) so as to compress the gas trapped in the pores of the rock, according to two different protocols.

Abstract: The method essentially comprises acquiring initial data obtained by laboratory measurements of the values, according to the initial permeability of the formations surrounding the well, of the thickness of the cakes and of the damaged permeability and restored permeability values of this zone, as a function of the distance to the wall of the well. Then the damaged zone is discretized by a 3D cylindrical grid pattern forming blocks of small radial thickness in relation to the diameter of the well, and the diffusivity equation, modelling the flow of the fluids through the cakes, is solved in this grid pattern by taking account of the measured initial data. Finally, the evolution of the permeability is modelled as a function of the flow rates of fluids flowing through the cakes, so as to deduce therefrom the optimum conditions to be applied for producing the well.

Abstract: A method of evaluating the capillary pressure curve of rocks of an underground reservoir from measurements on rock debris or fragments such as cuttings from the reservoir, over the total saturation range of these rocks, within a short period and at a low cost, from these measurements is disclosed. The method comprises measuring the permeability k of the debris, measuring the capillary pressure curve Pc as a function of the saturation of these fragments initially saturated with a fluid (brine for example) by subjecting them to centrifugation, and parametrizing a capillary pressure curve Pc satisfying empirical relations depending on adjustable parameters, constrained to adjust to an asymptotic part of the capillary curve measured by centrifugation, and to the value of permeability k measured on the cuttings, so as to obtain the whole of the capillary pressure curve. Applications include hydrocarbon reservoir evaluation.

Abstract: A method of evaluating the capillary pressure curve of rocks of an underground reservoir from measurements on rock debris or fragments such as cuttings from the reservoir, over the total saturation range of these rocks, within a short period and at a low cost, from these measurements is disclosed. The method comprises measuring the permeability k of the debris, measuring the capillary pressure curve Pc as a function of the saturation of these fragments initially saturated with a fluid (brine for example) by subjecting them to centrifugation, and parametrizing a capillary pressure curve Pc satisfying empirical relations depending on adjustable parameters, constrained to adjust to an asymptotic part of the capillary curve measured by centrifugation, and to the value of permeability k measured on the cuttings, so as to obtain the whole of the capillary pressure curve. Applications include hydrocarbon reservoir evaluation.

Abstract: Method and device for evaluating simultaneously, with the same equipment, physical parameters such as the absolute permeability and the porosity of fragments taken from a fragmented natural or artificial porous medium The porosity of the fragments is measured by means of helium pressure tests according to a protocol known in the art. The chamber (1) containing the fragments is communicated with a tank (11) whose volume is also known and containing helium at a known pressure. At pressure balance, the value of the solid volume can be deduced. The rock envelope volume and the fragments mass are also measured. Combining these measurements allows to determine the porosity of the samples and the density of the rock. Their permeability is then measured by immersing them in a viscous fluid and by communicating the chamber with viscous fluid at a determined pressure contained in a vessel (9) so as to compress the gas trapped in the pores of the rock, according to two different protocols.

Abstract: The present invention relates to a method and a fluid for drilling or intervening in a well passing through a porous, permeable formation, wherein a water-based well fluid is circulating in said well. In this method, there is added to the fluid not only the conventional ingredients for such a fluid but also a maximum of 10 wt. % of a composition obtained from a grease or oil and an alcohol, with the chain lengths of the acid and alcohol parts being chosen such that the ester thus obtained has sufficient dispersion in water, compatibility with said ingredients, does not form an emulsion with the reservoir oil, and adsorbs sufficiently on the porous formation.

Abstract: The present invention relates to a method and to a fluid for drilling or workover in a well running through a porous permeable formation, wherein a water-based well fluid circulates in said well. In the method, at most 3% by weight of a composition obtained from fat, or an oil, and an alcohol, is added to the fluid in addition to the conventional constituents for such a fluid, the chain lengths of the acid and alcohol parts being chosen such that the ester thus obtained has sufficient dispersion in water, compatibility with said constituents, does not form an emulsion with the reservoir oil and adsorbs sufficiently on the porous formation.

Abstract: Method of determining by numerical simulation the optimum conditions to be applied in a horizontal (or complex) well drilled through an underground reservoir so as to progressively eliminate (restore), by the fluids from the reservoir, deposits or cakes formed in at least a peripheral zone of the well as a result of drilling and completion operations.

Abstract: The invention relates to a method for characterizing a hydrocarbon reservoir comprising a gas cap (1) and an oil zone (2) with respectively Scwg and Scwo as the water saturation in each zone. The zone is invaded by gas either by gas injection, gas cap expansion or because of evolution of dissolved gases. In the method, the decrease in the initial water saturation Scwo in oil zone (6) during the displacement thereof by the gas is taken into account, the decrease being gradual down to Scwg which is distinctly below Scwo.

Abstract: The device includes a cell for a sample, delimited lengthwise by two end pieces (7, 8) and laterally by a deformable sheath (17). The end pieces are traversed by channels (14) which place their grooved inside faces in communication respectively with two sources (14, 15) at an adjustable pressure delivering respectively a first and a second fluid. Between the inside faces of the end pieces and the sample, two semipermeable membranes (12, 13) are disposed, which are permeable respectively to the first and to the second fluid. Electrodes (18, 19) are placed inside sheath (17) in contact with the sample and connected to a system (24) for measuring the electrical conductivity of the sample. The cell is placed in a body (1) associated with pressure means (28) for applying a confinement pressure to sheath (17) and membranes (12, 13). The device is designed to operate at relatively high temperatures.