Methods, systems, and computer-readable media for assessing porosity and water saturation cutoff values for hydrocarbon volume estimation are described. The techniques can include determining a plurality of water saturation and porosity value pairs for locations regularly-spaced along at least one borehole. The techniques can further include plotting the plurality of water saturation and porosity value pairs on a graph and representing a plurality of percentiles of the estimated maximal hydrocarbon volume on the graph. The techniques can also include causing the graph to be displayed to a user, such that the user can visually observe a combined sensitivity to porosity and water saturation cutoffs values. The user can take various actions based on the display.

Provided are embodiments that include determining cellular volumes having a saturation value for a given time that is above a threshold saturation value and having a location within a threshold distance of a perforation location of a production well, determining a nearest cell distance defined by a minimum distance between the perforation location and locations of the determined cellular volumes, determining an operating bottom-hole pressure (BHP) and a surface well pressure (SWP) for the well for the given time, determining a minimum operating BHP for the well for the given time according to a specified relationship of the operating BHP, the SWP, the threshold saturation value, the threshold distance, and the nearest cell distance, and operating the well at a production rate to maintain a BHP of the well at or above the minimum operating BHP for a time period associated with the given time.

Provided are embodiments that include determining cellular volumes having a saturation value for a given time that is above a threshold saturation value and having a location within a threshold distance of a perforation location of a production well, determining a nearest cell distance defined by a minimum distance between the perforation location and locations of the determined cellular volumes, determining an operating bottom-hole pressure (BHP) and a surface well pressure (SWP) for the well for the given time, determining a minimum operating BHP for the well for the given time according to a specified relationship of the operating BHP, the SWP, the threshold saturation value, the threshold distance, and the nearest cell distance, and operating the well at a production rate to maintain a BHP of the well at or above the minimum operating BHP for a time period associated with the given time.

A method for monitoring waterfront movement in a subsurface formation involves performing forward modeling of at least one deep electromagnetic survey of the waterfront movement, and determining locations for installing an electrically insulating spacer between well liners to form an on-demand electromagnetic source electrode. Based on the forward modeling, repeat survey time intervals are predicted. The method involves, during well completion, installing the electrically insulating spacer between the well liners in a reservoir to form at least one on-demand electromagnetic source electrode, and installing the electrically insulating spacer between the plurality of well liners in a reservoir to form an on-demand electromagnetic receiver electrode. A waterfront survey is performed by conveying a production logging tool into a well that temporarily converts the well liners into an on-demand electromagnetic source electrode and an on-demand receiver electrode, and inverse modeling of the waterfront survey is performed to produce a water saturation image.

The present invention discloses an adjustable karst water and soil loss simulation apparatus, comprising a surface runoff region, a vegetation buffer layer, a rainfall simulation apparatus, a bare rock-soil layer, a ponor, a slope adjuster, permeable layers, an underground river emergence point, a water receiving port, a glass perspective plate, a movable chassis and a waterproof base layer. The apparatus in the present invention can simulate special surface and underground dual environments in a karst environment, thereby aiding interpretation, providing simulation of a real environment under various environmental condition differences and bringing accurate water and soil loss data under similar conditions. Moreover, the apparatus has characteristics of transparent simulation, accurate numerical value, wide simulation application scope, simple structure, portability, convenient use, durability and the like.

The present invention discloses an adjustable karst water and soil loss simulation apparatus, comprising a surface runoff region, a vegetation buffer layer, a rainfall simulation apparatus, a bare rock-soil layer, a ponor, a slope adjuster, permeable layers, an underground river emergence point, a water receiving port, a glass perspective plate, a movable chassis and a waterproof base layer. The apparatus in the present invention can simulate special surface and underground dual environments in a karst environment, thereby aiding interpretation, providing simulation of a real environment under various environmental condition differences and bringing accurate water and soil loss data under similar conditions. Moreover, the apparatus has characteristics of transparent simulation, accurate numerical value, wide simulation application scope, simple structure, portability, convenient use, durability and the like.

A method and system for determining hydrologic conditions with respect to a surface point including generating one-dimensional columns representing hydrologic properties associated with the surface point to assist in determining the hydrologic conditions. The hydrologic conditions may be associated with historical conditions or a simulation of future conditions of the surface point.

Onshore electromagnetic (EM) reservoir monitoring systems and methods, including a system with a light source producing a light beam and an EM sensor array positioned above ground or buried underground over one or more regions of interest within a subterranean formation, the array coupled to the light source with an optical fiber. An EM sensor modulates the interrogation light beam in response to an EM signal induced into the subterranean formation by an EM source. The system further includes a processor controlling the light source, processing modulated light received from the array, and collecting data with the array to produce EM surveys, each EM survey based on data sets collected at different times. The EM sensor is physically isolated from a surrounding environment. The surveys are combined to produce a time lapse earth model of the regions of interest.

Onshore electromagnetic (EM) reservoir monitoring systems and methods, including a system with a light source producing a light beam and an EM sensor array positioned above ground or buried underground over one or more regions of interest within a subterranean formation, the array coupled to the light source with an optical fiber. An EM sensor modulates the interrogation light beam in response to an EM signal induced into the subterranean formation by an EM source. The system further includes a processor controlling the light source, processing modulated light received from the array, and collecting data with the array to produce EM surveys, each EM survey based on data sets collected at different times. The EM sensor is physically isolated from a surrounding environment. The surveys are combined to produce a time lapse earth model of the regions of interest.

Methods and systems for determining a liquid level above a horizontal segment of a wellbore in a formation are disclosed. Local temperatures and pressures are determined for each of a plurality of zones along the wellbore segment. For each zone, a local inflow rate is determined for fluids entering the wellbore from the formation. Based on the local inflow rate, local temperature, and local pressure, a local reservoir pressure is determined, and a local liquid level is determined based on the local reservoir pressure and a pressure associated with an injector wellbore positioned above the horizontal segment.