Simulating the control of solids in drilling fluids, and application to determining the size of cuttings

A method of modeling the loop circuit traveled by a drilling mud during drilling, including both the well and the surface equipment, in particular solid separation devices, in which for each time sequence, the loop circuit traveled by the mud is modeled by a network of logic units, each performing an elementary action:

• dividing or adding flows, separating-out solids, and adding a flow to a volume that is being emptied, with solids being separated-out in application of a partition function G in order to calculate the mass concentration of each liquid and solid species present in the mud, the total flow rate, and the grain size distribution of each solid species downstream from each item of equipment, and, wherein the parameters defining the logic units may be modified for each time sequence, and wherein the particle size distribution is defined by a normalized frequency function F of the type M a , b = ∫ a b ⁢ F ⁡ ( x ) ⁢ ⁢ ⅆ x
• where Ma,b is the mass percentage of particles of diameter lying in the range a to b and wherein F is normal function described by a median particle size value (d50) and a standard deviation coefficient σ, wherein σ=d50/d16.

A method of modeling the loop circuit traveled by a drilling mud during drilling, including both the well and the surface equipment, in particular solid separation devices, in which for each time sequence, the loop circuit traveled by the mud is modeled by a network of logic units, each performing an elementary action:

• dividing or adding flows, separating-out solids, and adding a flow to a volume that is being emptied, with solids being separated-out in application of a partition function G in order to calculate the mass concentration of each liquid and solid species present in the mud, the total flow rate, and the grain size distribution of each solid species downstream from each item of equipment, wherein the partition function is defined as the primitive of a normal distribution, Gi(x)dx being defined as the mass percentage in the “solid” effluent of particles of species i of size lying in the range x to x+dx, and characterized by a median value d50 and by a standard deviation coefficient.

A method of modeling the loop circuit traveled by a drilling mud during drilling, including both the well and the surface equipment, in particular solid separation devices, in which for each time sequence, the loop circuit traveled by the mud is modeled by a network of logic units, each performing an elementary action:

• dividing or adding flows, separating-out solids, and adding a flow to a volume that is being emptied, with solids being separated-out in application of a partition function G in order to calculate the mass concentration of each liquid and solid species present in the mud, the total flow rate, and the grain size distribution of each solid species downstream from each item of equipment, wherein the model includes predicting the efficiency coefficient of at least two solid control devices.

A method of modeling the loop circuit traveled by a drilling mud during drilling, including both the well and the surface equipment, in particular solid separation devices, in which for each time sequence, the loop circuit traveled by the mud is modeled by a network of logic units, each performing an elementary action:

• dividing or adding flows, separating-out solids, and adding a flow to a volume that is being emptied, with solids being separated-out in application of a partition function G in order to calculate the mass concentration of each liquid and solid species present in the mud, the total flow rate, and the grain size distribution of each solid species downstream from each item of equipment, and wherein for each solid separation device, a curve is generated for predicting the efficiency of separation as a function of the grain size of the cuttings.

A method of modeling the loop circuit traveled by a drilling mud during drilling, including both the well and the surface equipment, in particular solid separation devices, in which for each time sequence, the loop circuit traveled by the mud is modeled by a network of logic units, each performing an elementary action:

• dividing or adding flows, separating-out solids, and adding a flow to a volume that is being emptied, with solids being separated-out in application of a partition function G in order to calculate the mass concentration of each liquid and solid species present in the mud, the total flow rate, and the grain size distribution of each solid species downstream from each item of equipment, wherein the method includes the step of determining cuttings generation, modeled as an adder, said cuttings having a mass flow rate given by:
• q=π/4Φbit2(1+W)ROPρcuttings