Long horizontal wells are commonly drilled in the oil and gas industry to ensure maximum contact with a hydrocarbon bearing reservoir. Some of these wells are fitted with artificial lift systems to facilitate fluid production. However, long horizontal wells are susceptible to slugging flows, which in turn is detrimental to performance of the artificial lift system and subsequently affects the economic bottom line for the operator. Effective control of these slugging flows is therefore essential and beneficial for efficient production operations.
One of the current commercial systems used to control slugging flows downhole, separate fluids and solids downhole, and produce fluids to the surface is the Horizontal Enhanced Artificial Lift (HEAL) system, which is described, for example, in U.S. Patent Application No. 2018/0100384 (Saponja et al.). In the HEAL system, solids, liquid, and gas flow from a horizontal section of the well into a sized regulating tubing, which conditions the flow to ensure there is no slugging flow. At the end of the regulating tubing, a vortex separator separates the solids, liquid, and gas. The gas flows up an annulus between a pump and a casing to the surface, whereas the liquid and solids flow downwards by gravity. The liquid reverses direction around a corner and flows upwards towards the pump, while the solids continue their downward flow, where they accumulate at the HEAL seal within a solids sump.
The solids sump of the HEAL system is part of the casing in the well. Over time, solids accumulate in the sump, and the level of the solids rises to the turning corner where the liquid is separated from the solids. When this occurs, liquid supply is cut off from the pump. In other words, the pump can run dry or is starved of liquids. In addition, solids can be sucked into the inlet of the pump. Either or a combination of these events will result in a premature failure of the artificial lift system. In a more advanced case, even if the pump is shut in to prevent liquid starvation and solids ingestion, solids can also accumulate up to the discharge of the vortex separator. When this occurs, gas production stops, and the entire system is no longer operative.
In one aspect of the disclosure, a system for handling solids downhole includes a receptacle disposed in a wellbore. The receptacle has a top end, a closed bottom end, and a chamber between the top end and the closed bottom end. The receptacle is positioned to form a first annulus between the receptacle and the wellbore. The system includes a first tubing disposed in the wellbore and positioned to form a second annulus between the first tubing and the receptacle. The second annulus is fluidly connected to the chamber. The system includes a second tubing disposed in the wellbore and positioned to form a third annulus between the second tubing and the wellbore. The third annulus is fluidly connected to the first annulus, and the second tubing is fluidly connected to the first tubing. The system includes a first separation region formed at an end of the first annulus to separate a fluid stream carrying solids into a first separated stream that is reversed in direction into the second annulus and a second separated stream that continues to move in an uphole direction into the third annulus. The system includes a second separation region formed at an end of the first tubing to separate the first separated stream into a third separated stream that is reversed in direction into the first tubing and a fourth separated stream that continues to move in a downhole direction into the chamber.
The first separated stream may include a liquid component of the fluid stream and the solids, and the second separated stream may include a gas component of the fluid stream. The first tubing may extend into the chamber. The first separation region may be located proximate the top end of the receptacle. The second separation region may be located proximate a bottom end of the first tubing inside the chamber. The receptacle may be physically coupled to the first tubing, which may be physically coupled to the second tubing. The second tubing may be a production tubing. The system may include an artificial lift system disposed along the second tubing and operable to lift the third separated stream received in the first tubing up the second tubing.
The receptacle may include at least one port that is fluidly connected to the second annulus. The system may include an inlet check valve positioned in the at least one inlet port to control flow into the second annulus. The inlet check valve may be responsive to a pressure of the fluid stream. The receptacle may include at least one outlet port that is fluidly connected to the chamber. The system may include an outlet check valve positioned to control flow out of the at least one outlet port. The outlet check valve may be responsive to a fluid pressure inside the chamber. The system may include an artificial system disposed along the second tubing. The artificial lift system may be operable in a first mode to lift the third separated stream received in the first tubing up the second tubing and in a second mode to increase the fluid pressure within the chamber to at least a threshold pressure at which the outlet check valve opens.
In another aspect of the disclosure, an apparatus for handling solids includes a receptacle having a top end, a closed bottom end, and a chamber. The top end has at least one inlet port and a central bore. A first tubing is inserted into the chamber through the central bore. A second tubing is physically and fluidly connected to the first tubing. An artificial lift system is disposed along the second tubing.
The receptacle may include at least one outlet port that is fluidly connected to the chamber. The apparatus may include an inlet check valve positioned to control flow through the at least one inlet port and an outlet check valve positioned to control flow through the at least one outlet port. The artificial lift system may be operable to pump fluid in a first direction in one mode and in a second direction that is opposed to the first direction in a second mode.
In yet another aspect of the disclosure, a method for handling solids downhole includes disposing a tubing in a wellbore. The method includes disposing a receptacle in the wellbore and proximate a bottom end of the tubing. The method includes receiving a reservoir fluid stream carrying solids in a first annulus formed between the receptacle and the wellbore from a producing zone of the wellbore. The method includes separating the reservoir fluid stream into a first separated stream and a second separated stream at a first separation region formed at an end of the first annulus. The first separated stream is reversed in direction into a second annulus formed between the tubing and receptacle. The second separated stream is directed in an uphole direction into a third annulus formed between the tubing and the wellbore. The first separated stream is separated into a third separated stream and a fourth separated stream at a second separation region formed at an end of the second annulus. The third separated stream is reversed in direction into the tubing. The fourth separated stream is directed in a downhole direction into a chamber of the receptacle.
The method may include lifting the third separated stream received in the tubing to a surface location. The method may include retrieving the tubing and receptacle to a surface location and emptying the chamber. The method may include conditioning the reservoir fluid stream to prevent slugging prior to separating the reservoir fluid stream.
The act of reversing the first separated stream in direction into the second annulus formed between the tubing and the receptacle may include directing the first separated stream into the second annulus through at least one inlet check valve positioned at an inlet of the second annulus. The method may include flushing out the chamber through one or more outlet ports formed in the receptacle by increasing a fluid pressure within the chamber to open at least one check valve positioned to control flow out of the one or more outlet ports. The act of increasing the fluid pressure within the chamber may include operating an artificial lift system disposed along the tubing to pump fluid into the chamber.
The act of separating the reservoir fluid stream into the first separated stream and the second separated stream at the first separation region may include separating out a liquid component of the reservoir fluid stream and the solids as the first separated stream and separating out a gas component of the reservoir fluid stream as the second separated stream. The act of separating the first separated stream into the third separated stream and the fourth separated stream at the second separation region may include separating out the liquid component carried by the first separated stream as the third separated stream and separating out the solids carried by the first separated stream as the fourth separated stream.
The foregoing general description and the following detailed description are exemplary of the invention and are intended to provide an overview or framework for understanding the nature of the invention as it is claimed. The accompanying drawings are included to provide further understanding of the invention and are incorporated in and constitute a part of the specification. The drawings illustrate various embodiments of the invention and together with the description serve to explain the principles and operation of the invention.
The following is a description of the figures in the accompanying drawings. In the drawings, identical reference numbers identify similar elements or acts. The sizes and relative positions of elements in the drawings are not necessarily drawn to scale. For example, the shapes of various elements and angles are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve drawing legibility. Further, the particular shapes of the elements as drawn are not necessarily intended to convey any information regarding the actual shape of the particular elements and have been solely selected for ease of recognition in the drawing.
In the following detailed description, certain specific details are set forth in order to provide a thorough understanding of various disclosed implementations and embodiments. However, one skilled in the relevant art will recognize that implementations and embodiments may be practiced without one or more of these specific details, or with other methods, components, materials, and so forth. In other instances, related well known features or processes have not been shown or described in detail to avoid unnecessarily obscuring the implementations and embodiments. For the sake of continuity, and in the interest of conciseness, same or similar reference characters may be used for same or similar objects or features in multiple figures.
System, method, and apparatus for handling solids after separating the solids from gas and liquid are described herein. The system, method, and apparatus effectively remove an accumulated amount of solids from the well. The system, method, and apparatus may provide a benefit of elongating production operation and improving the bottom line for the operator, especially in long horizontal wells with high sand concentrations.
Top wall 116 includes a central bore 136. A tubing 140 is disposed in central bore 136 and extends into chamber 120. An annulus 144 is defined between an inner surface of receptacle 104 and an outer surface of a portion of tubing 140 disposed inside chamber 120. Annulus 144 may be referred to as a collector-tubing annulus. Collector-tubing annulus 144 is located in an upper part of chamber 120 and is fluidly connected to inlet ports 124. An imaginary line 146 is shown demarcating collector-tubing annulus 144 from chamber portion 120a below tubing 140. In reality, collector-tubing annulus 144 and chamber portion 120a are fluidly connected. An outer surface of tubing 140 may include a threaded section 148. An inner surface of top wall 116 defining central bore 136 may include threaded section 152 that is complementary to the threaded section 148. Threaded sections 148, 152 may engage each other to form a threaded connection between tubing 140 and receptacle 104 and thereby secure tubing 140 to receptacle 104. Alternatively, a flanged connection may be used to secure tubing 140 to receptacle 104. As shown in
In the illustrated example, solids collector 100 is located within liner 220. Although not shown, solids collector 100 may also extend into an open hole section of the wellbore. In the illustrated example, solids collector 100 is in a bent section of wellbore 204, with a portion of solids collector 100 in a vertical section of wellbore 204 and another portion of solids collector 100 in a horizontal section of wellbore 204. An annulus 236 is formed between receptacle 104 of solids collector 100 and a portion of wellbore 204 including liner 220. Annulus 236 may be referred to as collector-casing annulus. Collector-casing annulus 236 extends from the bottom end of receptacle 104 (i.e., the end proximate bottom wall 108) to the top end of receptacle 104 (i.e., the end proximate top wall 116). An annulus 240 is formed between wellbore tubular 200 and a portion of wellbore 204 including casing 216. Annulus 240 may be referred to as tubing-casing annulus. Annulus 240 is fluidly connected to annulus 236. In some cases, as shown in
Returning to
The solids-liquid stream received in inlet ports 124 travels down collector-tubing annulus 144. At the bottom of tubing 140 is a second separation region where the solids-liquid stream separates into a third stream that reverses in direction and enters tubing 140, as shown by arrows 256, and a fourth stream that continues to move downward into chamber portion 120a, as shown by arrows 260. The third stream that reverses in direction and enters tubing 140 includes substantially a liquid component of the solids-liquid stream. The fourth stream that continues to move downward into chamber portion 120a includes substantially the solid component of the solids-liquid stream. The separation of the solids-liquid stream at the bottom of tubing 140 is aided by both gravity and suction created by the artificial lift system 232 at the bottom of tubing 140. Artificial lift system 232 is operated to pump the liquid stream entering tubing 140 up wellbore tubular 200 to the surface. At the surface, the liquid stream may enter a pumping tee 264 mounted on surface wellhead 228 and flow into a flowline 268 through a side outlet of pumping tee 264.
While the liquid stream is pumped to the surface, the solids settle within chamber 120. For illustration purposes, solids 276 are shown accumulating inside chamber 120. At scheduled intervals or when the amount of solids in chamber 120 rises to a given level, production is stopped and wellbore tubular 200 and solids collector 100 are retrieved to the surface. As an example, solids concentration in the well can be monitored at the surface. Based on the density of solids, and liquid production rate, the volume of solids can be estimated. The time for a certain volume of solids to equal the volume of the solids collector below the end of tubing 140 can be used as a guide to schedule retrieval of the solids collector to the surface. At the surface, solids collector 100 is emptied and serviced. To empty solids collector 100, tubing 140 is separated from wellbore tubular 200. After separating tubing 140 from wellbore tubular 200, tubing 140 may be separated from receptacle 104, which will leave the central bore 136 (in
Check valves 184 may be arranged in inlet ports 124 formed in top wall 116″ of receptacle 104″ to control flow into collector-tubing annulus 144. In one example, check valves 184 may be flapper valves or swing-type valves. In one example, a valve element 184a, e.g., a flapper, of the check valve 184 is spring-loaded and normally rests against a valve seat 188 formed in top wall 116″. Valve elements 184a can be pushed down to allow an incoming fluid stream to enter collector-tubing annulus 144 from inlet ports 124. Valve elements 184a return to the valve seat 188 when there is no incoming fluid stream or when the pressure of the incoming fluid stream is insufficient to push valve elements 184a away from valve seats 188. In this closed position of check valves 184, chamber 120 can be pressurized, e.g., for the purpose of flushing out chamber 120. When chamber 120 is pressurized, fluids and solids within chamber 120 can push on valve elements 184a from below. However, since valve elements 184a rest firmly against valve seats 188, check valves 184 will remain closed.
Solids collector 100″ has been illustrated with tubing 140 attached to top wall 116″ by a threaded connection. In an alternative implementation, tubing 140 may be attached to top wall 116″ by a flanged connection, as previously described with respect to
While the liquid stream is pumped to the surface, the solids settle within chamber 120. When the amount of solids reaches a given level within chamber 120 or at a prescheduled time, production is stopped to allow chamber 120 to be flushed out. When production is stopped, the pressure at inlet ports 124 is reduced such that inlet valves 184 close. To flush the contents of chamber 120 out, artificial lift system 232″ is operated in reverse to pump fluid into chamber 120. When the pressure in chamber 120 exceeds the cracking pressure of valve 172, valve 172 opens to allow the contents of chamber 120 to be flushed out through outlet ports 168.
The detailed description along with the summary and abstract are not intended to be exhaustive or to limit the embodiments to the precise forms described. Although specific embodiments, implementations, and examples are described herein for illustrative purposes, various equivalent modifications can be made without departing from the spirit and scope of the disclosure, as will be recognized by those skilled in the relevant art.