diff --git a/SimPEG/Examples/EM_Schenkel_Morrison_Casing.py b/SimPEG/Examples/EM_Schenkel_Morrison_Casing.py new file mode 100644 index 00000000..ef51b25c --- /dev/null +++ b/SimPEG/Examples/EM_Schenkel_Morrison_Casing.py @@ -0,0 +1,269 @@ +from SimPEG import * +from SimPEG.EM import FDEM, Analytics, mu_0 +import time + +try: + from pymatsolver import MumpsSolver + solver = MumpsSolver +except Exception: + solver = SolverLU + pass + +def run(plotIt=True): + """ + EM: Schenkel and Morrison Casing Model + ====================================== + + Here we will create and run a FDEM forward simulation based on the + Schenkel and Morrison Casing Model + + - `Schenkel, C.J., and H.F. Morrison, 1990`_, Effects of well casing on potential field measurements using downhole current sources: Geophysical prospecting, 38, 663-686. + + .. _Schenkel, C. J., and H. F. Morrison, 1990: http://onlinelibrary.wiley.com/store/10.1111/j.1365-2478.1990.tb01868.x/asset/j.1365-2478.1990.tb01868.x.pdf?v=1&t=imdt3o85&s=38248af166c2887ed587d94c8ccafad30b480529 + + The model consists of: + - Air: Conductivity 1e-8 S/m, above z = 0 + - Background: conductivity 1e-2 S/m, below z = 0 + - Casing: conductivity 1e6 S/m + - 300m long + - radius of 0.1m + - thickness of 6e-3m + + Inside the casing, we take the same conductivity as the background. + + We are using an EM code to simulate DC, so we use frequency low enough + that the skin depth inside the casing is longer than the casing length (f + = 1e-6 Hz). The plot produced is of the current inside the casing. + + These results are shown in the SEG abstract by Yang et al., 2016: 3D DC + resistivity modeling of steel casing for reservoir monitoring using + equivalent resistor network. The solver used to produce these results and + achieve the CPU time of ~30s is Mumps, which was installed using pymatsolver_ + + .. _pymatsolver: https://github.com/rowanc1/pymatsolver + + """ + + if plotIt: + import matplotlib.pylab as plt + + # ------------------ MODEL ------------------ + sigmaair = 1e-8 # air + sigmaback = 1e-2 # background + sigmacasing = 1e6 # casing + sigmainside = sigmaback # inside the casing + + + casing_t = 0.006 # 1cm thickness + casing_l = 300 # length of the casing + + casing_r = 0.1 + casing_a = casing_r - casing_t/2. # inner radius + casing_b = casing_r + casing_t/2. # outer radius + casing_z = np.r_[-casing_l,0.] + + + # ------------------ SURVEY PARAMETERS ------------------ + freqs = np.r_[1e-6] #[1e-1, 1, 5] # frequencies + dsz = -300 # down-hole z source location + src_loc = np.r_[0.,0.,dsz] + inf_loc = np.r_[0.,0.,1e4] + + print 'Skin Depth: ', [(500./np.sqrt(sigmaback*_)) for _ in freqs] + + + # ------------------ MESH ------------------ + # fine cells near well bore + csx1, csx2 = 2e-3, 60. + pfx1, pfx2 = 1.3, 1.3 + ncx1 = np.ceil(casing_b/csx1+2) + + # pad nicely to second cell size + npadx1 = np.floor(np.log(csx2/csx1) / np.log(pfx1)) + hx1a,hx1b = Utils.meshTensor([(csx1,ncx1)]),Utils.meshTensor([(csx1,npadx1,pfx1)]) + dx1 = sum(hx1a)+sum(hx1b) + dx1 = np.floor(dx1/csx2) + hx1b *= (dx1*csx2 - sum(hx1a))/sum(hx1b) + + # second chunk of mesh + dx2 = 300. # uniform mesh out to here + ncx2 = np.ceil((dx2 - dx1)/csx2) + npadx2 = 45 + hx2a, hx2b = Utils.meshTensor([(csx2,ncx2)]), Utils.meshTensor([(csx2,npadx2,pfx2)]) + hx = np.hstack([hx1a,hx1b,hx2a,hx2b]) + + # z-direction + csz = 0.05 + nza = 10 + ncz, npadzu, npadzd = np.int(np.ceil(np.diff(casing_z)[0]/csz))+10, 68, 68 # cell size, number of core cells, number of padding cells in the x- direction + hz = Utils.meshTensor([(csz,npadzd,-1.3), (csz,ncz), (csz,npadzu,1.3)]) # vector of cell widths in the z-direction + + # Mesh + mesh = Mesh.CylMesh([hx,1.,hz], [0.,0.,-np.sum(hz[:npadzu+ncz-nza])]) + + print 'Mesh Extent xmax: %f,: zmin: %f, zmax: %f'%(mesh.vectorCCx.max(), mesh.vectorCCz.min(), mesh.vectorCCz.max()) + print 'Number of cells', mesh.nC + + if plotIt is True: + fig, ax = plt.subplots(1, 1, figsize=(6, 4)) + ax.set_title('Simulation Mesh') + mesh.plotGrid(ax=ax) + plt.show() + + # Put the model on the mesh + sigWholespace = sigmaback*np.ones((mesh.nC)) + + sigBack = sigWholespace.copy() + sigBack[mesh.gridCC[:,2] > 0.] = sigmaair + + sigCasing = sigBack.copy() + iCasingZ = (mesh.gridCC[:,2] <= casing_z[1]) & (mesh.gridCC[:,2] >= casing_z[0]) + iCasingX = (mesh.gridCC[:,0] >= casing_a) & (mesh.gridCC[:,0] <= casing_b) + iCasing = iCasingX & iCasingZ + sigCasing[iCasing] = sigmacasing + + + if plotIt is True: + + # plotting parameters + xlim = np.r_[0., 0.2] + zlim = np.r_[-350., 10.] + clim_sig = np.r_[-8,6] + + # plot models + fig, ax = plt.subplots(1,1,figsize=(4,4)) + + f = plt.colorbar(mesh.plotImage(np.log10(sigCasing),ax=ax)[0], ax=ax) + ax.grid(which='both') + ax.set_title('Log_10 (Sigma)') + ax.set_xlim(xlim) + ax.set_ylim(zlim) + f.set_clim(clim_sig) + + plt.show() + + + # -------------- Sources -------------------- + # Define Custom Current Sources + + # surface source + sg_x = np.zeros(mesh.vnF[0],dtype=complex) + sg_y = np.zeros(mesh.vnF[1],dtype=complex) + sg_z = np.zeros(mesh.vnF[2],dtype=complex) + + nza = 2 # put the wire two cells above the surface + ncin = 2 + + # vertically directed wire + sgv_indx = (mesh.gridFz[:,0] > casing_a) & (mesh.gridFz[:,0] < casing_a + csx1) # hook it up to casing at the surface + sgv_indz = (mesh.gridFz[:,2] <= +csz*nza) & (mesh.gridFz[:,2] >= -csz*2) + sgv_ind = sgv_indx & sgv_indz + sg_z[sgv_ind] = -1. + + # horizontally directed wire + sgh_indx = (mesh.gridFx[:,0] > casing_a) & (mesh.gridFx[:,0] <= inf_loc[2]) + sgh_indz = (mesh.gridFx[:,2] > csz*(nza-0.5)) & (mesh.gridFx[:,2] < csz*(nza+0.5)) + sgh_ind = sgh_indx & sgh_indz + sg_x[sgh_ind] = -1. + + sgv2_indx = (mesh.gridFz[:,0] >= mesh.gridFx[sgh_ind,0].max()) & (mesh.gridFz[:,0] <= inf_loc[2]*1.2) # hook it up to casing at the surface + sgv2_indz = (mesh.gridFz[:,2] <= +csz*nza) & (mesh.gridFz[:,2] >= -csz*2) + sgv2_ind = sgv2_indx & sgv2_indz + sg_z[sgv2_ind] = 1. + + # assemble the source + sg = np.hstack([sg_x,sg_y,sg_z]) + sg_p = [FDEM.Src.RawVec_e([],_,sg/mesh.area) for _ in freqs] + + # downhole source + dg_x = np.zeros(mesh.vnF[0],dtype=complex) + dg_y = np.zeros(mesh.vnF[1],dtype=complex) + dg_z = np.zeros(mesh.vnF[2],dtype=complex) + + # vertically directed wire + dgv_indx = (mesh.gridFz[:,0] < csx1) # go through the center of the well + dgv_indz = (mesh.gridFz[:,2] <= +csz*nza) & (mesh.gridFz[:,2] > dsz + csz/2.) + dgv_ind = dgv_indx & dgv_indz + dg_z[dgv_ind] = -1. + + # couple to the casing downhole + dgh_indx = mesh.gridFx[:,0] < casing_a + csx1 + dgh_indz = (mesh.gridFx[:,2] < dsz + csz) & (mesh.gridFx[:,2] >= dsz) + dgh_ind = dgh_indx & dgh_indz + dg_x[dgh_ind] = 1. + + # horizontal part at surface + dgh2_indx = mesh.gridFx[:,0] <= inf_loc[2]*1.2 + dgh2_indz = sgh_indz.copy() + dgh2_ind = dgh2_indx & dgh2_indz + dg_x[dgh2_ind] = -1. + + # vertical part at surface + dgv2_ind = sgv2_ind.copy() + dg_z[dgv2_ind] = 1. + + # assemble the source + dg = np.hstack([dg_x,dg_y,dg_z]) + dg_p = [FDEM.Src.RawVec_e([],_,dg/mesh.area) for _ in freqs] + + # ------------ Problem and Survey --------------- + survey = FDEM.Survey(sg_p + dg_p) + mapping = [('sigma', Maps.IdentityMap(mesh))] + problem = FDEM.Problem_h(mesh, mapping=mapping) + problem.pair(survey) + + # ------------- Solve --------------------------- + t0 = time.time() + fieldsCasing = problem.fields(sigCasing) + print 'Time to solve 2 sources', time.time() - t0 + + # Plot current + + # current density + jn0 = fieldsCasing[dg_p,'j'] + jn1 = fieldsCasing[sg_p,'j'] + + # current + in0 = [mesh.area*fieldsCasing[dg_p,'j'][:,i] for i in range(len(freqs))] + in1 = [mesh.area*fieldsCasing[sg_p,'j'][:,i] for i in range(len(freqs))] + + in0 = np.vstack(in0).T + in1 = np.vstack(in1).T + + # integrate to get z-current inside casing + inds_inx = (mesh.gridFz[:,0] >= casing_a) & (mesh.gridFz[:,0] <= casing_b) + inds_inz = (mesh.gridFz[:,2] >= dsz ) & (mesh.gridFz[:,2] <= 0) + inds_fz = inds_inx & inds_inz + + indsx = [False]*mesh.nFx + inds = list(indsx) + list(inds_fz) + + in0_in = in0[np.r_[inds]] + in1_in = in1[np.r_[inds]] + z_in = mesh.gridFz[inds_fz,2] + + in0_in = in0_in.reshape([in0_in.shape[0]/3,3]) + in1_in = in1_in.reshape([in1_in.shape[0]/3,3]) + z_in = z_in.reshape([z_in.shape[0]/3,3]) + + I0 = in0_in.sum(1).real + I1 = in1_in.sum(1).real + z_in = z_in[:,0] + + if plotIt is True: + fig, ax = plt.subplots(1,2,figsize=(12,4)) + + ax[0].plot(z_in,np.absolute(I0), z_in,np.absolute(I1)) + ax[0].legend(['top casing', 'bottom casing'],loc='best') + ax[0].set_title('Magnitude of Current') + + ax[1].semilogy(z_in,np.absolute(I0), z_in,np.absolute(I1)) + ax[1].legend(['top casing', 'bottom casing'],loc='best') + ax[1].set_title('Magnitude of Current') + ax[1].set_ylim([1e-2, 1.]) + + plt.show() + +if __name__ == '__main__': + run() + diff --git a/SimPEG/Examples/__init__.py b/SimPEG/Examples/__init__.py index cce22296..4647ad90 100644 --- a/SimPEG/Examples/__init__.py +++ b/SimPEG/Examples/__init__.py @@ -5,6 +5,7 @@ import DC_Analytic_Dipole import DC_Forward_PseudoSection import EM_FDEM_1D_Inversion import EM_FDEM_Analytic_MagDipoleWholespace +import EM_Schenkel_Morrison_Casing import EM_TDEM_1D_Inversion import FLOW_Richards_1D_Celia1990 import Forward_BasicDirectCurrent @@ -19,7 +20,7 @@ import Mesh_Tensor_Creation import MT_1D_ForwardAndInversion import MT_3D_Foward -__examples__ = ["DC_Analytic_Dipole", "DC_Forward_PseudoSection", "EM_FDEM_1D_Inversion", "EM_FDEM_Analytic_MagDipoleWholespace", "EM_TDEM_1D_Inversion", "FLOW_Richards_1D_Celia1990", "Forward_BasicDirectCurrent", "Inversion_Linear", "Mesh_Basic_PlotImage", "Mesh_Basic_Types", "Mesh_Operators_CahnHilliard", "Mesh_QuadTree_Creation", "Mesh_QuadTree_FaceDiv", "Mesh_QuadTree_HangingNodes", "Mesh_Tensor_Creation", "MT_1D_ForwardAndInversion", "MT_3D_Foward"] +__examples__ = ["DC_Analytic_Dipole", "DC_Forward_PseudoSection", "EM_FDEM_1D_Inversion", "EM_FDEM_Analytic_MagDipoleWholespace", "EM_Schenkel_Morrison_Casing", "EM_TDEM_1D_Inversion", "FLOW_Richards_1D_Celia1990", "Forward_BasicDirectCurrent", "Inversion_Linear", "Mesh_Basic_PlotImage", "Mesh_Basic_Types", "Mesh_Operators_CahnHilliard", "Mesh_QuadTree_Creation", "Mesh_QuadTree_FaceDiv", "Mesh_QuadTree_HangingNodes", "Mesh_Tensor_Creation", "MT_1D_ForwardAndInversion", "MT_3D_Foward"] ##### AUTOIMPORTS ##### diff --git a/docs/examples/EM_Schenkel_Morrison_Casing.rst b/docs/examples/EM_Schenkel_Morrison_Casing.rst new file mode 100644 index 00000000..54e74dba --- /dev/null +++ b/docs/examples/EM_Schenkel_Morrison_Casing.rst @@ -0,0 +1,52 @@ +.. _examples_EM_Schenkel_Morrison_Casing: + +.. --------------------------------- .. +.. .. +.. THIS FILE IS AUTO GENEREATED .. +.. .. +.. SimPEG/Examples/__init__.py .. +.. .. +.. --------------------------------- .. + + +Schenkel and Morrison Casing Model +================================== + + we will create and run a FDEM forward simulation based on the +nkel and Morrison Casing Model + +chenkel, C.J., and H.F. Morrison, 1990`_, Effects of well casing on potential field measurements using downhole current sources: Geophysical prospecting, 38, 663-686. + +Schenkel, C. J., and H. F. Morrison, 1990: http://onlinelibrary.wiley.com/store/10.1111/j.1365-2478.1990.tb01868.x/asset/j.1365-2478.1990.tb01868.x.pdf?v=1&t=imdt3o85&s=38248af166c2887ed587d94c8ccafad30b480529 + +model consists of: +r: Conductivity 1e-8 S/m, above z = 0 +ckground: conductivity 1e-2 S/m, below z = 0 +sing: conductivity 1e6 S/m +- 300m long +- radius of 0.1m +- thickness of 6e-3m + +de the casing, we take the same conductivity as the background. + +re using an EM code to simulate DC, so we use frequency low enough + the skin depth inside the casing is longer than the casing length (f +-6 Hz). The plot produced is of the current inside the casing. + +e results are shown in the SEG abstract by Yang et al., 2016: 3D DC +stivity modeling of steel casing for reservoir monitoring using +valent resistor network. The solver used to produce these results and +eve the CPU time of ~30s is Mumps, which was installed using pymatsolver_ + +pymatsolver: https://github.com/rowanc1/pymatsolver + + + +.. plot:: + + from SimPEG import Examples + Examples.EM_Schenkel_Morrison_Casing.run() + +.. literalinclude:: ../../SimPEG/Examples/EM_Schenkel_Morrison_Casing.py + :language: python + :linenos: