System and method for determining bottomhole conditions during flowback operations of a shale reservoir

A method of determining fracture properties in a hydraulically fractured reservoir, the method comprising:

• measuring fluid properties, via one or more sensors, of fluids produced at a surface-location of a well that traverses the hydraulically fractured reservoir, wherein the measured fluid properties include flow rates of different fluid phases that are part of the fluids, and wherein the different fluid phases are selected from the group including an oil phase, a gas phase, a water phase, and a solid phase;
• using a transient fluid flow simulator to determine at least one fracture property at at least one bottomhole location of the well over time based on the measured fluid properties, wherein the at least one fracture property characterizes fracture conductivity of a fracture in a near-wellbore region adjacent the well;
• and
• controlling a flowback operation in the well based at least in part on the at least one fracture property;
• wherein controlling the flowback operation in the well further comprises:
• calculating a drawdown pressure in the well at a particular time, wherein the drawdown pressure in the well is a function of a rate of a bottomhole pressure change and a bottomhole fluid rate;
• determining when the calculated drawdown pressure is outside a particular safe zone defined by upper and lower limits on drawdown pressure as a function of time;
• and
• adjusting a surface-located choke in response to determining the calculated drawdown pressure is outside the particular safe zone.

A method of determining at least one bottomhole condition in a well, the method comprising:

• measuring fluid properties, via one or more sensors, of fluids produced at a surface-location of the well, wherein the well traverses a hydraulically fractured reservoir, wherein the measured fluid properties include flow rates of different fluid phases that are part of the fluids, and wherein the different fluid phases are selected from the group including an oil phase, a gas phase, a water phase, and a solid phase;
• using a transient fluid flow simulator to determine composition and properties of the fluids in the well between a surface-location of the well and at least one bottomhole-location of the well based on the measured fluid properties and based on calculations involving data derived during drilling the well;
• calculating at least one bottomhole condition in the well based on the determined composition and properties of the fluids in the well between the surface-location and the at least one bottomhole-location of the well;
• and
• controlling a flowback operation in the well based at least in part on the at least one bottomhole condition;
• wherein controlling the flowback operation in the well further comprises:
• calculating a drawdown pressure in the well at a particular time, wherein the drawdown pressure in the well is a function of a rate of a bottomhole pressure change and a bottomhole fluid rate;
• determining when the calculated drawdown pressure is outside a particular safe zone defined by upper and lower limits on drawdown pressure as a function of time;
• and
• adjusting a surface-located choke in response to determining the calculated drawdown pressure is outside the particular safe zone.

A method of determining at least one bottomhole condition in a well, the method comprising:

• measuring fluid properties, via one or more sensors, of fluids produced at a surface-location of the well, wherein the well traverses a hydraulically fractured reservoir, wherein the measured fluid properties include flow rates of different fluid phases that are part of the fluids, and wherein the different fluid phases are selected from the group including an oil phase, a gas phase, a water phase, and a solid phase;
• using a transient fluid flow simulator to determine composition and properties of the fluids in the well between a surface-location of the well and at least one bottomhole-location of the well based on the measured fluid properties;
• calculating at least one bottomhole condition in the well based on the determined composition and properties of the fluids in the well between the surface-location and the at least one bottomhole-location of the well, wherein calculating the at least one bottomhole condition in the well includes calculating multiple estimates of bottomhole pressure and a statistical distribution of the bottomhole pressure;
• and
• controlling a flowback operation in the well based at least in part on the at least one bottomhole condition;
• wherein controlling the flowback operation in the well further comprises:
• calculating a drawdown pressure in the well at a particular time, wherein the drawdown pressure in the well is a function of a rate of a bottomhole pressure change and a bottomhole fluid rate;
• determining when the calculated drawdown pressure is outside a particular safe zone defined by upper and lower limits on drawdown pressure as a function of time;
• and
• adjusting a surface-located choke in response to determining the calculated drawdown pressure is outside the particular safe zone.