Subsurface injection of reject stream

Recovering oil from a subterranean formation is disclosed, comprising processing a source water to produce a processed water stream and a reject water stream; injecting a first fluid into an injection well toward a first downhole exhaust, wherein the first fluid comprises the processed water stream; and injecting a second fluid into the injection well toward a second downhole exhaust, wherein the second fluid comprises the reject water stream or a produced water stream, wherein the first fluid is separated from the second fluid within the injection well; and producing oil via a production well.

FIELD OF THE INVENTION

The present invention is directed to methods for producing hydrocarbon-containing compositions from a subterranean formation and, more particularly, to recovering hydrocarbons using an aqueous recovery formulation.

BACKGROUND OF THE INVENTION

In the recovery of oil from a subterranean formation, primary recovery methods utilizing the natural formation pressure to produce the oil typically allow recovery of only a portion of the oil contained within the formation. Additional oil and hydrocarbon compounds from the formation may be produced by improved oil recovery (e.g. water injection) or enhanced oil recovery (EOR) methods.

Typically, water used in improved oil recovery and/or enhanced oil recovery production operations must be processed. Processing the source water generally includes filtering the water to remove solid particles and removing dissolved solids. Nanofiltration, Ultrafiltration, and/or Reverse Osmosis membranes can be used in this filtration process. The membrane filtration process usually generates a filtered water stream containing a reduced amount of dissolved solids, and often generates a rejection stream with a more concentrated amount of dissolved solids than the pre-filtered water.

The resulting rejection stream must be directed somewhere. In the case of oil production operations in the ocean, the rejection stream can usually be safely outlet back into the ocean. However, there are some seawater environments in which the rejection stream cannot be sent back to the source water environment, either for environmental, regulatory, or some other reason. In addition, injection operations occurring on land or where a natural sink for the rejection stream is not present, the rejection stream must typically be directed to a reject water storage, be further processed, and/or be hauled offsite from the production operation. It is desirable to find a way to use or dispose of the rejection water produced by water processing more efficiently.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to methods for producing hydrocarbon-containing compositions from a subterranean formation and, more particularly, to recovering hydrocarbons using an aqueous recovery formulation.

To facilitate a better understanding of the present disclosure, the following examples of certain embodiments are given. In no way should the following examples be read to limit, or define, the scope of the invention.

Referring now toFIG. 1, a system100for producing hydrocarbons from at least one subterranean formation4,6,8is illustrated. The system100may comprise a production well12traversing at least one formation4and comprising openings in formation6through which fluids may flow between the formation6and the production well12. The system100may comprise an injection well32traversing at least one formation4and comprising openings in formation6, through which fluids may flow between the formation6and the injection well32. In certain embodiments, the production well12and/or the injection well may traverse a body of water2. The formation6may comprise fractures and/or perforations14,34proximate to the production well12and/or the injection well32. The production well12may be connected to a production facility10located at the surface and structured and arranged to direct production fluids from the production well12toward the production facility10. The production facility10may comprise a production fluid storage16and/or a gas storage18.

In certain embodiments, the production facility10may comprise a water production facility30. In certain embodiments, aqueous components of the production fluid received by the production facility10may be separated and sent to the water production facility30. In certain embodiments, the production facility10may be able to process water, for example from the body of water2and/or the production well12to produce a processed water, which may be stored in the water production facility30. The processed water may be pumped into an injection well32as an EOR flood toward formation6, to aid in the flow of production fluids from the formation6into the production well12. In certain embodiments, the EOR flood may be the processed water alone or a component of a chemical injection flood. In certain embodiments, water from the EOR flood flowing into the production well12may be recycled at the production facility10, for example by returning water to water production facility30, where it may be processed, then re-injected into the injection well32.

In certain embodiments, the system100may comprise a plurality of injection wells32. For example, in certain embodiments, the system100may comprise 2 to 100 injection wells. In certain embodiments, the system100may comprise a plurality of production wells12. For example, in certain embodiments, the system100may comprise 2 to 100 production wells12.

Referring now toFIG. 2A, an example injection well201is shown extending into a first formation206and a second formation208and comprising a first opening216within the first formation206and a second opening218within the second formation208. The injection well201may comprise an injection well inner wall212and a cavity214disposed within the injection well201and defined by the injection well inner wall212. In certain embodiments, the injection well201may extend from a surface205into at least a first formation206and a second formation208.

The injection well201may comprise a first spacer222disposed within the injection well cavity214and engaging the injection well inner wall212. The injection well201may comprise a second spacer224disposed within the injection well cavity214and engaging the injection well inner wall212. In certain embodiments, the second spacer224may be downhole from the first spacer222.

A first injection zone230may be defined between the first spacer222and the second spacer224, within the injection well cavity214. In certain embodiments, a second injection zone231may be defined downhole of the second spacer224within the injection well cavity214. In certain embodiments, the second spacer224may substantially prevent fluid flow between the first and second injection zones230,231. In certain embodiments, the second injection zone231may extend to a downhole end240of the injection well201. In certain embodiments, the second injection zone231may extend to a third spacer located within the injection well cavity214.

In certain embodiments, a formation permeability barrier207may be disposed between the first formation206and the second formation208. The formation permeability barrier207may have a lower permeability to oil and/or water than the first formation206and the second formation208. As a result, flow of oil and/or water between the first formation206and the second formation208may be restricted. In certain embodiments, the formation permeability barrier207may define the lower bounds of the first formation206and the upper bounds of the second formation208. In certain embodiments, the first spacer222and/or the second spacer224may be located adjacent to a formation permeability barrier207.

The injection well201may comprise a first opening216within the first injection zone230and a second opening218within the second injection zone231. The first opening216may fluidly connect the first injection zone230with the first formation206, allowing fluid flow between the first injection zone230and the first formation206. The second opening218may fluidly connect the second injection zone231with the second formation208, allowing fluid flow between the second injection zone231and the second formation208.

In certain embodiments, the injection well201may comprise a first conduit202disposed within the cavity214and a second conduit204disposed within the cavity214. The first conduit202and the second conduit204may extend from the surface205into the injection well201.

In certain embodiments, the first conduit202may extend through the first spacer222and fluidly connect the surface205to the first injection zone230. The first conduit202may comprise a first downhole exhaust232within the first injection zone230.

In certain embodiments, the second conduit204may extend within the cavity through the first spacer222and the second spacer224and comprise a second downhole exhaust234within the second injection zone231.

In certain embodiments, a first fluid pumped into the first conduit202may be directed into the first injection zone230and into the first formation206. A second fluid pumped into the second conduit204may be directed into the second injection zone231and into the second formation208. The first fluid and the second fluid may be substantially separated within the injection well201by the first and second conduits202,204and/or the first and second spacers222,224.

The first fluid may be one of an oil recovery fluid, an enhanced oil recovery fluid, a processed water, a reject water, a produced water, or a combination sink water. The second fluid may be one of an oil recovery fluid, an enhanced oil recovery fluid, a processed water, a reject water, a produced water, or a combination sink water. Processing a source water may generate a processed water stream and a reject water stream. Produced water may be obtained from the production well along with other formation fluids such as oil and/or gas. Oil recovery fluid and enhanced oil recovery fluid may comprise processed water.

The first fluid and the second fluid may be any combination of these fluids. For example, in certain embodiments, the first fluid may be an oil recovery fluid and the second fluid may be the reject water. For example, the first fluid may be the reject water and the second fluid may be the produced water. For example, the first fluid may be an enhanced oil recovery fluid and the second fluid may be the produced water. Although several examples of these combinations are provided, the present disclosure does not intend to be limited to these combinations and contemplates injecting any combination of fluids into the first conduit and the second conduit.

FIG. 2Bshows an example injection well201as described inFIG. 2A, extending into a unified formation250and comprising a first opening216and second opening218within the unified formation250, where the first opening216is uphole from the second opening218. The first conduit202may direct fluid into the first injection zone230and into an upper area of the unified formation250through the first opening216. The second conduit204may direct fluid into the second injection zone231and into a lower area of the unified formation250, through the second opening218. The second fluid injected into the lower area of the unified formation250may aid oil recovery from the unified formation250. For example, where the first fluid is an enhanced oil recovery fluid and the second fluid is a reject fluid, the reject fluid may drive oil and/or gas within the unified formation250upward, toward the enhanced oil recovery fluid in the upper area of the unified formation250.

Referring now toFIG. 2C, an injection well260is shown comprising a third conduit265. The injection well201may comprise an injection well inner wall272and a cavity274disposed within the injection well260and defined by the injection well outer wall272.

In certain embodiments, the injection well260may comprise a first spacer282disposed within the injection well cavity274and engaging the injection well inner wall272, a second spacer284disposed within the injection well cavity274and engaging the injection well inner wall272, and a third spacer286disposed within the injection well cavity274and engaging the injection well inner wall272. In certain embodiments, the second spacer284may be downhole from the first spacer282and the third spacer286may be downhole from the first spacer282and the second spacer284.

A first injection zone290may be defined between the first spacer282and the second spacer284, within the injection well cavity274. In certain embodiments, a second injection zone291may be defined downhole of the second spacer284within the injection well cavity274. In certain embodiments, a third injection zone292may be defined downhole of the third spacer286within the injection well cavity274. In certain embodiments, the second spacer284may substantially prevent fluid flow between the first and second injection zones290,291. In certain embodiments, the third spacer286may substantially prevent fluid flow between the second and third injection zones291,292.

The injection well260may comprise a first opening276within a first injection zone290, a second opening278within a second injection zone291, and a third opening279within a third injection zone292. The first opening276may fluidly connect the first injection zone290with a first formation. The second opening278may fluidly connect the second injection zone291with a second formation. The third opening279may fluidly connect the third injection zone292with a third formation.

In certain embodiments, the injection well260may comprise a first conduit262disposed within the cavity274, a second conduit264disposed within the cavity274, and a third conduit265disposed within the cavity274. The first conduit262, the second conduit264, and the third conduit265may extend from the surface205into the injection well260. In certain embodiments, the first conduit262may extend through the first spacer282and fluidly connect the surface205to the first injection zone290. The first conduit262may comprise a first downhole exhaust293within the first injection zone290. In certain embodiments, the second conduit264may extend through the first spacer282and the second spacer284and fluidly connect the surface205to the second injection zone291. The second conduit264may comprise a second downhole exhaust294within the second injection zone291. In certain embodiments, the third conduit265may extend through the first spacer282, the second spacer284, and the third spacer286and fluidly connect the surface205to the third injection zone292. The third conduit265may comprise a third downhole exhaust295within the second injection zone292.

In certain embodiments, a first fluid pumped into the first conduit262may be directed into the first injection zone290and through the first opening276. A second fluid pumped into the second conduit264may be directed into the second injection zone291and through the second opening278. A third fluid pumped into the third conduit265may be directed into the third injection zone292and through the third opening279. The first fluid, the second fluid, and the third fluid may be substantially separated within the injection well260.

Referring now toFIGS. 3A and 3B,FIG. 3Ashows an example injection well301extending into a first formation306and a second formation308, andFIG. 3Bis a top-view of the injection well301, according to certain embodiments. The injection well301may comprise a first conduit302and a second conduit304within the first conduit302and concentric to the first conduit302. The injection well301may comprise an injection well inner wall312and a cavity314disposed within the injection well301and defined in the annulus between the second conduit302and the injection well outer wall312. In certain embodiments, the injection well301may extend from a surface305into at least a first formation306and a second formation308.

The injection well301may comprise a first spacer322disposed in an annulus between the first conduit302and the second conduit304. The injection well301may comprise a second spacer324disposed within the injection well cavity314and between the injection well inner wall312and the second conduit304. In certain embodiments, the second spacer324may be downhole from the first spacer322.

A first injection zone330may be defined within the injection well cavity314above the second spacer324, for example, between the first spacer322and the second spacer324. In certain embodiments, a second injection zone331may be defined downhole of the second spacer324within the injection well cavity314. In certain embodiments, the second spacer324may substantially prevent fluid flow between the first and second injection zones330,331. In certain embodiments, the second injection zone331may extend to a downhole end340of the injection well301.

In certain embodiments, a formation permeability barrier307may be disposed between the first formation306and the second formation308. The formation permeability barrier307may have a lower permeability to oil and/or water than the first formation206and the second formation308. As a result, flow of oil and/or water between the first formation306and the second formation308may be restricted. In certain embodiments, the formation permeability barrier307may define the lower bounds of the first formation306and the upper bounds of the second formation308. In certain embodiments, the first spacer322and/or the second spacer324may be located adjacent to a formation permeability barrier307.

The injection well301may comprise a first opening316within the first injection zone330and a second opening318within the second injection zone231. The first opening316may fluidly connect the first injection zone330with the first formation306, allowing fluid flow between the first injection zone330and the first formation306. The second opening318may fluidly connect the second injection zone331with the second formation308, allowing fluid flow between the second injection zone331and the second formation308.

In certain embodiments, the first conduit302may extend through the first spacer322and fluidly connect the surface305to the first injection zone330. The first conduit302may comprise a first downhole exhaust332within the first injection zone330.

In certain embodiments, the second conduit304may extend within the cavity through the second spacer324and comprise a second downhole exhaust334within the second injection zone331.

The first conduit302may direct a first fluid into the first injection zone330, where the first fluid may flow into the first formation306through the first openings316. The second conduit304may direct a second fluid into the second injection zone331, where the second fluid may flow into the second formation308through second openings318. The first fluid and the second fluid may be substantially separated within the injection well301by the first and second conduits302,304and/or the first and second spacers322,324.

In certain embodiments, the first fluid may be an EOR fluid and the second fluid may be a reject water. For example, the reject water may be produced from processing the water using a reverse osmosis device, as will be discussed herein. In certain embodiments, the first fluid may be the reject water and the second fluid may be the EOR fluid.

Referring now toFIG. 4, an injection system400is shown comprising a water processing system401. The water processing system401processes a source water402and generates a processed water420and a reject water422. In certain embodiments, the processed water420may be injected into an injection well405via a first conduit430. In certain embodiments, an alkaline component, a polymer, a surfactant, and/or other chemical component may optionally be added to the processed water at425to generate an enhanced oil recovery (EOR) fluid.

In certain embodiments, the reject water422may be injected into the injection well405via a second conduit422. In certain embodiments, the reject water422may be combined with a produced water415before injection into the injection well405. In certain embodiments, the produced water415may be injected alone into the injection well405via the second conduit422. Although not shown inFIG. 4, in certain embodiments, the produced water may be injected into the injection well via the first conduit430.

Referring now toFIG. 5, a water processing system501is illustrated, according to aspects of the present disclosure. The water processing system501may comprise obtaining a source water502. The source water may comprise seawater, fresh water, brine, well water, produced water, connate water, or water from any other water supply. The source water502may be pre-filtered at step504, which may include removing large particles and/or suspended material from the source water. For example, a large particle strainer may be used at step504to pre-filter the source water.

At step506, in certain embodiments, some dissolved solids may be removed from the source water. For example, in certain embodiments, a nanofiltration device and/or an ultrafiltration device may remove some dissolved solids from the source water. In certain embodiments, step506may comprise removing some divalent cations from the source water. For example, in certain embodiments, at step506, 60% to 99% of the divalent cations present in the source water may be removed.

At step508, the source water may be deaerated to remove some air from the source water. In certain embodiments, deaeration may come before removing dissolved solids from the source water. In certain embodiments, deaeration of the source water may occur at any point prior to pumping the water downhole.

At step512, the source water may be filtered using a filtration device to produce a processed water stream520and a reject water stream522. For example, in certain embodiments, the filtration device may comprise a nano-filtration (NR) device and/or a reverse osmosis (RO) device. In certain embodiments, the filtration device may produce the processed water stream520and the reject water stream522in substantially equal volumes. For example, filtering a source water comprising seawater using an RO device may produce a processed water stream520and a reject water stream522in a ratio of substantially 1:1 (i.e., with substantially equal volumes). In certain embodiments, the filtration device may produce the processed water stream520and the reject water stream522in different volumes. For example, filtering a source water comprising sea water using an NF device may produce a processed water stream520and a reject water stream522in a respective ratio of 3:1 (i.e., about 0.75 L of processed water may be produced for every 0.25 L of reject water). In certain embodiments, the ratio of processed water to reject water produced by the filtration device may depend on the total dissolved solid (TDS) concentration of the source water, for example lower TDS concentration may lower the volume of reject water produced for each volume of source water filtered. The reject water stream522may have a higher TDS concentration than the processed water stream520. In certain embodiments, the reject water stream522may have a higher TDS concentration than the source water input into the filtration device at step512.

Optionally, the processed water stream520may be combined with at least one chemical component to produce a chemical flood. The processed water stream520and/or the chemical flood comprising the processed water stream may be directed into an EOR flood conduit530. The EOR flood may be pumped into a target formation from which hydrocarbons are produced. In certain embodiments, the EOR flood conduit530may comprise the first conduit and/or the second conduit as discussed in connection toFIGS. 2A-2C. In certain embodiments, the EOR flood conduit530may comprise the first conduit and/or the second conduit as discussed in connection toFIGS. 3A and 3B. As such, the processed water stream520may be pumped through an injection well via the first conduit or the second conduit and into a first formation or a second formation.

The reject water stream522may be directed into a reject water conduit532. In certain embodiments, the reject water conduit532may comprise the first conduit and/or the second conduit as discussed in connection toFIGS. 2A-2C. In certain embodiments, the reject water conduit532may comprise the first conduit and/or the second conduit as discussed in connection toFIGS. 3A and 3B. As such, the reject water stream522may be pumped through an injection well via the first conduit or the second conduit and into a first formation or a second formation.

In certain embodiments, the reject water stream522may be pumped into the second formation below the target formation for production. Injection of reject water into the second formation may aid in recovery of oil from the first formation through creation of a density gradient (i.e., between water in the lower formation layer and less dense oil in the upper formation layer). The reject water stream522may also aid in production of oil from the second formation by pushing and/or mobilizing hydrocarbons toward the production well.

The present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. While systems, methods, and compositions are described in terms of “comprising,” “containing,” or “including” various components or steps, the systems, methods, and compositions can also “consist essentially of” or “consist of” the various components and steps. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from a to b,” or, equivalently, “from a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Whenever a numerical range having a specific lower limit only, a specific upper limit only, or a specific upper limit and a specific lower limit is disclosed, the range also includes any numerical value “about” the specified lower limit and/or the specified upper limit. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces.