Use of Scale Soft Pitzer to Calculate Deposition, or Precipitation, in a Reservoir or Core Material During Long Term Flow
Use of ScaleSoftPitzer to calculate deposition, or precipitation, in a reservoir or core material during long term flow.
Approach will be presented in four steps:
1. Determine whether equilibrium, kinetics, or mass transport is controlling, 2. Relate precipitation to the physical variables in the field or laboratory core, 3. Relate the physical variables that affect scale formation or dissolution to space and time in the reservoir or core material, and 4. Combine the two into a single description explicitly and implicitly.
Two physical geometries will be examined algebraically, 1st(left). linear flow as might occur in a laboratory column, and 2nd(right). radial flow as might ideally represent flow into or out from a well in a reservoir. Pictorially, these can be represented as follows:
height(m) re,Pe,equilibium rw,Pw(well) r,P(pressure) radius, r(m) flow, Q(m3/s) height(m) re,Pe,equilibium rw,Pw(well) r,P(pressure) radius, r(m) flow, Q(m3/s)
Two flow regimes will be considered for each geometry: A. no gas phase present, as is common with laboratory cores or in deep reservoirs at pressure, and B. with a gas phase is present. The difference is important to CaCO3, FeCO3, FeS, etc., but will no direct effect upon BaSO4, CaSO4’s, NaCl, etc.
Objective: Express the fractional change in porosity, n/n, in terms of flow conditions, brine composition, and time. Specifically, the calculation of n/n can be considered to be composed of four parts, illustrated here for calcite deposition or dissolution:
Summary of approach: the precipitation of, e.g., calcite, d(Ca2+,M), will be expressed as a function of pressure change, dP(psi), which will be expressed in terms of flow rate, Q(m3/s, or B/d) and reservoir properties, such as permeability, k(m2, or md) and porosity.
1. Relate kinetics and mass transport. First, estimate the average distance, or time, that brine will flow for half of the amount that can precipitate to precipitate, i.e.,
Approach will be presented in four steps:
1. Determine whether equilibrium, kinetics, or mass transport is controlling, 2. Relate precipitation to the physical variables in the field or laboratory core, 3. Relate the physical variables that affect scale formation or dissolution to space and time in the reservoir or core material, and 4. Combine the two into a single description explicitly and implicitly.
Two physical geometries will be examined algebraically, 1st(left). linear flow as might occur in a laboratory column, and 2nd(right). radial flow as might ideally represent flow into or out from a well in a reservoir. Pictorially, these can be represented as follows:
height(m) re,Pe,equilibium rw,Pw(well) r,P(pressure) radius, r(m) flow, Q(m3/s) height(m) re,Pe,equilibium rw,Pw(well) r,P(pressure) radius, r(m) flow, Q(m3/s)
Two flow regimes will be considered for each geometry: A. no gas phase present, as is common with laboratory cores or in deep reservoirs at pressure, and B. with a gas phase is present. The difference is important to CaCO3, FeCO3, FeS, etc., but will no direct effect upon BaSO4, CaSO4’s, NaCl, etc.
Objective: Express the fractional change in porosity, n/n, in terms of flow conditions, brine composition, and time. Specifically, the calculation of n/n can be considered to be composed of four parts, illustrated here for calcite deposition or dissolution:
Summary of approach: the precipitation of, e.g., calcite, d(Ca2+,M), will be expressed as a function of pressure change, dP(psi), which will be expressed in terms of flow rate, Q(m3/s, or B/d) and reservoir properties, such as permeability, k(m2, or md) and porosity.
1. Relate kinetics and mass transport. First, estimate the average distance, or time, that brine will flow for half of the amount that can precipitate to precipitate, i.e.,