def truncate_log(log, top, bottom): """ Remove unreliable values in the top and bottom section of well log Parameters ---------- log : Log object top, bottom : scalar depth value Returns ------- trunc_log : Log object """ depth = np.array(log.depth) data = np.array(log.data) if top != 0: mask = depth < top data[mask] = np.nan if bottom != 0: mask = depth > bottom data[mask] = np.nan trunc_log = Log() trunc_log.name = log.name + '_trunc' trunc_log.units = log.units trunc_log.descr = log.descr trunc_log.depth = depth trunc_log.data = data return trunc_log
def smooth_log(log, window=1500): """ Parameters ---------- log : Log object log to smooth window : scalar window size of the median filter Returns ------- smoothed log : Log object smoothed log """ data = np.array(log.data) depth = np.array(log.depth) mask = np.isfinite(data) func = interp1d(depth[mask], data[mask]) interp_data = func(depth[log.start_idx: log.stop_idx]) new_data = np.array(data) new_data[log.start_idx: log.stop_idx] = interp_data smoothed = smooth(new_data[log.start_idx: log.stop_idx], window_len=window//2, window='flat') # using half the window length in order to be consistent with opendtect smooth_data = np.array(data) smooth_data[log.start_idx: log.stop_idx] = smoothed log_smooth = Log() log_smooth.name = log.name + "_sm" log_smooth.units = log.units log_smooth.descr = log.descr log_smooth.depth = log.depth log_smooth.data = smooth_data return log_smooth
def obp_well(den_log, kb=41, wd=82, rho_w=1.01): """ Compute Overburden Pressure for a Log Parameters ---------- den_log : Log density log (extrapolated) kb : scalar kelly bushing elevation in meter wd : scalar from sea level to sea bottom (a.k.a mudline) in meter rho_w : scalar density of sea water - depending on the salinity of sea water (1.01-1.05g/cm3) Returns ------- out : Log Log containing overburden pressure in mPa """ depth = np.array(den_log.depth) rho = np.array(den_log.data) obp = overburden_pressure( depth, rho, kelly_bushing=kb, depth_w=wd, rho_w=rho_w) obp_log = Log() obp_log.depth = depth obp_log.data = obp obp_log.name = "log_obp" obp_log.descr = "Overburden_Pressure" obp_log.units = "MPa" return obp_log
def interpolate_log(log): """ Log curve interpolation """ depth = np.array(log.depth) data = np.array(log.data) mask = np.isfinite(data) func = interp1d(depth[mask], data[mask]) interp_data = func(depth[log.start_idx: log.stop_idx]) data[log.start_idx: log.stop_idx] = interp_data interp_log = Log() interp_log.name = log.name + '_interp' interp_log.units = log.units interp_log.descr = log.descr interp_log.depth = depth interp_log.data = data return interp_log
def hydrostatic_well(depth, kb=0, wd=0, rho_f=1., rho_w=1.): """ Returns ------- Log Hydrostatic pressure as a Log """ hydrostatic = hydrostatic_pressure( depth, kelly_bushing=kb, depth_w=wd, rho_f=rho_f, rho_w=rho_w) hydro_log = Log() hydro_log.depth = np.array(depth) hydro_log.data = hydrostatic hydro_log.name = 'log_hydro' hydro_log.descr = "Hydrostatic_Pressure" hydro_log.units = "MPa" return hydro_log
def normal_log(vel_log, a, b): """ Returns ------- Log normal velocity log """ normal_vel = normal(np.array(vel_log.depth), a, b) mask = np.isnan(np.array(vel_log.data)) normal_vel[mask] = np.nan log = Log() log.depth = np.array(vel_log.depth) log.data = normal_vel log.name = 'normal_vel_log' log.descr = "Velocity_normal" log.units = "m/s" return log
def extrapolate_log_traugott(den_log, a, b, kb=0, wd=0): """ Extrapolate density log using Traugott equation """ density_trend = traugott_trend(np.array(den_log.depth), a, b, kb=kb, wd=wd) extra_log = Log() extra_log.name = den_log.name + "_ex" extra_log.units = den_log.units extra_log.descr = "Density_extra" extra_log.depth = np.array(den_log.depth) new_data = np.full_like(density_trend, np.nan) new_data[:den_log.start_idx] = density_trend[:den_log.start_idx] old_data = np.array(den_log.data) new_data[den_log.start_idx:] = old_data[den_log.start_idx:] extra_log.data = new_data return extra_log
def hydrostatic_well(depth, kb=0, wd=0, rho_f=1., rho_w=1.): """ Returns ------- Log Hydrostatic pressure as a Log """ hydrostatic = hydrostatic_pressure(depth, kelly_bushing=kb, depth_w=wd, rho_f=rho_f, rho_w=rho_w) hydro_log = Log() hydro_log.depth = np.array(depth) hydro_log.data = hydrostatic hydro_log.name = 'log_hydro' hydro_log.descr = "Hydrostatic_Pressure" hydro_log.units = "MPa" return hydro_log
def upscale_log(log, freq=20): """ downscale a well log with a lowpass butterworth filter """ depth = np.array(log.depth) data = np.array(log.data) mask = np.isfinite(data) func = interp1d(depth[mask], data[mask]) interp_data = func(depth[log.start_idx: log.stop_idx]) nyq = 10000 / 2 dw = freq / nyq b, a = butter(4, dw, btype='low', analog=False) filtered = filtfilt(b, a, interp_data, method='gust') downscale_data = np.array(data) downscale_data[log.start_idx: log.stop_idx] = filtered log_downscale = Log() log_downscale.name = log.name + "_downscale_" + str(freq) log_downscale.units = log.units log_downscale.descr = log.descr log_downscale.depth = log.depth log_downscale.data = downscale_data return log_downscale
def obp_well(den_log, kb=41, wd=82, rho_w=1.01): """ Compute Overburden Pressure for a Log Parameters ---------- den_log : Log density log (extrapolated) kb : scalar kelly bushing elevation in meter wd : scalar from sea level to sea bottom (a.k.a mudline) in meter rho_w : scalar density of sea water - depending on the salinity of sea water (1.01-1.05g/cm3) Returns ------- out : Log Log containing overburden pressure in mPa """ depth = np.array(den_log.depth) rho = np.array(den_log.data) obp = overburden_pressure(depth, rho, kelly_bushing=kb, depth_w=wd, rho_w=rho_w) obp_log = Log() obp_log.depth = depth obp_log.data = obp obp_log.name = "log_obp" obp_log.descr = "Overburden_Pressure" obp_log.units = "MPa" return obp_log
def shale(log, vsh_log, thresh=0.35): """ Discern shale intervals log : Log log to discern vsh_log : Log shale volume log thresh : scalar percentage threshold, 0 < thresh < 1 """ shale_mask = np.isfinite(vsh_log.depth) shale_mask[vsh_log.start_idx: vsh_log.stop_idx] = True mask_thresh = np.array(vsh_log.data) < thresh mask = shale_mask * mask_thresh data = np.array(log.data) data[mask] = np.nan log_sh = Log() log_sh.name = log.name + "_sh" log_sh.units = log.units log_sh.descr = log.descr log_sh.depth = log.depth log_sh.data = data return log_sh