Process method and system for separating solid phase in well completion fluid and application
By employing ultrasonic destabilization, flocculation-gravity settling, and flotation processes, combined with specific flocculants and inhibitors, the problem of removing impurities from flowback solid-free completion fluids has been solved, achieving efficient liquid-solid separation and recycling of completion fluids.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-09
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies struggle to efficiently remove organic and inorganic impurities from flowback solid-free completion fluids, leading to difficulties in liquid-solid separation and impacting the recyclability of the completion fluid.
The process employs ultrasonic destabilization, flocculation-gravity sedimentation and flotation, combined with a composite flocculant of cationic polyacrylamide and polyaluminum ferric chloride, as well as hydrophilic inhibitors and foam modifiers, to achieve liquid-solid separation and impurity removal.
It effectively reduces the content of insoluble solids in completion fluid to less than 1%, with a reuse rate of over 85%, meeting the requirements for recycling, reducing treatment costs, and minimizing environmental pollution.
Smart Images
Figure CN121827718A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of oil and gas well completion fluid flowback, and particularly relates to a solid phase separation process method and system for completion fluid and application. BACKGROUND
[0002] In the completion process of oil and gas field exploitation, completion fluid is needed. In order to maximize the protection of oil and gas layers, reduce the pollution of solid particles to the oil and gas layers, and effectively improve the oil and gas production, the solid-free composite brine completion fluid is more and more widely used in completion operations due to its excellent oil and gas layer protection performance. The completion fluid will be polluted by residual components such as water-based drilling fluid and oil-based drilling fluid during the operation process, so that the content of insoluble organic impurities and inorganic impurities carried in the liquid phase of the completion fluid flowback from the wellhead exceeds 5%, and in some cases, even exceeds 10%. The high solid content of the completion fluid seriously affects its recycling performance. On the one hand, the particle size of part of the insoluble solid phase in the completion fluid is small, and the active sites such as Mg, Al and Fe in the inorganic solid phase are easy to adsorb the organic components in the completion fluid, so that the solid phase is uniformly suspended in the system; on the other hand, the existence of vacancy / steric stabilization effect further increases the difficulty of liquid-solid separation. In view of this situation, the current treatment technologies mainly include "flocculation + centrifugation + membrane separation", "flocculation + pressure filtration", "natural sedimentation + static separation" and the like. SUMMARY
[0003] In order to realize the efficient recycling of the flowback solid-free completion fluid, and enrich the process route and increase the selection space by taking out the organic and inorganic moderate impurities in the flowback solid-free completion fluid in industrial application, the present application provides a solid phase separation process method and system for completion fluid and application.
[0004] In the first aspect, the present application provides a solid phase separation process method for completion fluid, which can include:
[0005] The completion fluid to be separated and treated is placed in an ultrasonic system for ultrasonic destabilization treatment at an ultrasonic power of 400-1200W and an ultrasonic time of 4-8min;
[0006] The completion fluid after ultrasonic destabilization treatment is transferred to a flocculation-high gravity sedimentation system, and after adding a composite flocculating agent into the flocculation-high gravity sedimentation system for 2-5min, liquid-solid pre-separation is performed on the stable flocculation; wherein the composite flocculating agent is a mixture of cationic polyacrylamide and polyaluminum ferric chloride;
[0007] The completion fluid after pre-separation is placed in a flotation system, a hydrophilic depressant is added into the flotation system for 3min, and then a foam adjusting agent is added into the flotation system for 15min.
[0008] In one embodiment, the cationic polyacrylamide is added in a range of 0.2-0.8 mg / L, the polymeric ferric aluminum chloride is added in a range of 25-45 mg / L; the centrifugal force of the flocculation-ultra high gravity sedimentation system is in a range of 3500-4500 g.
[0009] In another embodiment, the cationic polyacrylamide is added in a range of 0.4-0.8 mg / L, the polymeric ferric aluminum chloride is added in a range of 30-45 mg / L, and the medicament acting time is 4-5 min.
[0010] The centrifugal force of the flocculation-ultra high gravity sedimentation system is in a range of 4000-4500 g.
[0011] In another embodiment, the cationic polyacrylamide is added in a range of 0.4-0.6 mg / L, the polymeric ferric aluminum chloride is added in a range of 30-35 mg / L.
[0012] In another embodiment, the hydrophilic inhibitor is a salted water glass, an acidified water glass or a soluble starch; the hydrophilic inhibitor is added in a range of 0.2-10 mg / L.
[0013] The foam regulator is kerosene or silicon oil; the foam regulator is added in a range of 0.1-1 mg / L.
[0014] In another embodiment, the hydrophilic inhibitor is added in a range of 3-10 mg / L; the foam regulator is added in a range of 0.3-1 mg / L.
[0015] In another embodiment, the hydrophilic inhibitor is added in a range of 3-5 mg / L; the foam regulator is added in a range of 0.3-0.6 mg / L.
[0016] In another embodiment, the ultrasonic power of the ultrasonic system is 600-1200 W, and the ultrasonic time is 6-8 min.
[0017] In another embodiment, the ultrasonic power of the ultrasonic system is 600-800 W.
[0018] In a second aspect, an embodiment of the present application provides a solid phase separation system in a completion fluid, which can include: an ultrasonic system, a flocculation-ultra high gravity sedimentation system, a flotation system.
[0019] The ultrasonic system is used for ultrasonic destabilization treatment of the well completion fluid to be separated at an ultrasonic power of 400-1200 W and an ultrasonic time of 4-8 min; the flocculation-high gravity sedimentation system is used for liquid-solid pre-separation of the stable flocculation after the composite flocculant acts for 2-5 min; and the flotation system is used for adding the hydrophilic inhibitor to the pre-separated well completion fluid for 3 min and then adding the foam regulator for 15 min of flotation operation.
[0020] In a third aspect, the application provides an application of the well completion fluid separated by the well completion fluid solid phase separation process in the well completion engineering.
[0021] The beneficial effects of the above technical solutions provided by the embodiments of the application at least include:
[0022] The well completion fluid solid phase separation process, system and application provided by the embodiments of the application can realize efficient recycling of the flowback solid-free well completion fluid, remove organic and inorganic moderate impurities from the flowback solid-free well completion fluid in industrial application, and thus enrich the process route and increase the selection space.
[0023] Further, the method takes the flowback solid-free well completion fluid as a treatment object, and after the destabilization, flocculation + high gravity sedimentation and flotation treatment, the insoluble solid content of the well completion fluid can be reduced to within 1%, preferably meeting the recycling requirement, and the recycling rate is higher than 85%, which promotes the well completion operation to a green, environmentally friendly and low-carbon new stage.
[0024] The entire treatment process mainly uses physical means, the addition amount of the flotation reagent and the flocculation reagent is ppm level, and the composition mainly comprises inorganic salts, which preferably guarantees the recycling performance of the well completion fluid, and the treatment process is simple and the treatment cost per ton is low (less than 30 yuan).
[0025] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims.
[0026] The technical solutions of the application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS
[0027] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, and are used together with the embodiments of the application to explain the application, and do not constitute a limitation on the application. In the drawings:
[0028] Figure 1 It is one of the flowcharts of the well completion fluid solid phase separation process provided in the embodiments of the application.
[0029] Figure 2 Figure 2 is a flow chart of a process for separating solid phase in the well completion fluid according to an embodiment of the present application;
[0030] Figure 3 Figure 3 is a diagram of mineral composition analysis of inorganic impurities in the well completion fluid according to an embodiment of the present application;
[0031] Figure 4 Figure 4 is an effect diagram of drying impurities in the well completion fluid according to an embodiment of the present application. DETAILED DESCRIPTION
[0032] Exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.
[0033] The inventors found in practical work applications that the "flocculation + centrifugation + membrane separation" technology has high processing cost and high membrane replacement frequency, and on the other hand, part of the useful components (formate, inorganic salt, etc.) in the well completion fluid are seriously lost during the processing; the "flocculation + pressure filtration" technology has little effect on the removal of ultra-fine particle (≤8um) impurities, and has great limitations in the range of use; the "natural sedimentation + static separation" processing method has low efficiency (10-15d of sedimentation is required), and on the other hand, 30-45% of the liquid phase is wasted (i.e., due to the sedimentation result being divided into three layers of upper, middle and lower, only the middle layer can be reused). In summary, it is necessary to design and develop a method that has industrial application prospects and can efficiently remove organic and inorganic mixed impurities in the returned solid-free well completion fluid to solve the above problems. In view of the above problems, the present application is proposed in order to provide a solid phase separation process method, system and application in well completion fluid which overcomes the above problems or at least partially solves the above problems.
[0034] A solid phase separation process method in well completion fluid is provided in an embodiment of the present application, referring to Figure 1 and Figure 2 the specific operation can include the following steps:
[0035] Step S11, the well completion fluid to be separated and treated (containing solid content exceeding 5%) is placed in an ultrasonic system for ultrasonic destabilization treatment; the space stability state of the well completion fluid system is broken through this step, and under the influence of cavitation effect, the separation of inorganic solid phase and organic phase is realized.
[0036] Step S12: Transfer the ultrasonically destabilized completion fluid to the flocculation-gravity settling system, and add a composite flocculant to the flocculation-gravity settling system to perform liquid-solid pre-separation of the stable flocs; wherein the composite flocculant is a mixture of cationic polyacrylamide and polyaluminum ferric chloride.
[0037] After pre-separation in step S12, the liquid phase after liquid-solid pre-separation enters the flotation system, and further removes ultrafine insoluble particles in step S13.
[0038] Step S13: Place the pre-separated completion fluid into the flotation system, add a hydrophilic inhibitor to the flotation system, and then add a foam modifier to the flotation system for flotation operation.
[0039] The solid-phase separation process in the completion fluid provided in this embodiment of the invention first places the flowback completion fluid with a solid content of more than 5% in an ultrasonic system for destabilization, thereby achieving the separation of the organic phase and the inorganic solid phase. The destabilized completion fluid then enters a flocculation + ultragravity sedimentation system to achieve liquid-solid pre-separation. The liquid phase after liquid-solid pre-separation then enters a flotation system to further remove insoluble ultrafine particles, so that the solid content of the liquid phase is reduced to below 1%, meeting the requirements for recycling the completion fluid.
[0040] The flowback completion fluid used in this embodiment of the invention was taken from an oilfield mud station. The elemental analysis, mineral composition, particle size distribution of inorganic impurities, and four-component composition analysis of organic impurities in the completion fluid are as follows:
[0041] Table 1. XRF elemental analysis results of inorganic impurities in the well completion fluid to be separated.
[0042]
[0043] Table 2. Results of Inorganic Impurity Mineral Composition in the Well Completion Fluid to be Separated
[0044]
[0045] Table 3. Particle size distribution of inorganic impurities in the well completion fluid to be separated and treated.
[0046]
[0047]
[0048] Table 4. Analysis results of the four components of organic impurities in the completion fluid to be separated and treated.
[0049]
[0050] Referring to Tables 1 to 4 above, and Figure 3As shown, the inorganic impurity minerals in the well completion fluid to be treated in the embodiment of the application mainly include quartz and feldspar, and contain a certain amount of bentonite and mica.
[0051] The commercial sources of the raw materials used in the embodiment of the application are shown in Table 5 as follows:
[0052] Table 5 Commercial sources of the raw materials used in the embodiment of the application and the comparative examples
[0053]
[0054] Example 1:
[0055] A certain amount of the flowback well completion fluid with 11.28% insoluble solid phase was placed in an ultrasonic system, and set at an ultrasonic power of 400 W and an ultrasonic time of 4 min for destabilization treatment; a composite flocculant was added to the destabilized well completion fluid, wherein the addition amount of CPAM was 0.2 mg / L, the addition amount of PFAC was 25 mg / L, the action time of the reagent was 2 min, and then supergravity sedimentation was carried out under a centrifugal force of 3500 g; the liquid phase obtained by the supergravity sedimentation was introduced into a flotation system, 0.2 mg / L of salted water glass was added to the liquid phase, fully stirred for 3 min, and then 0.1 mg / L of a foam regulator kerosene (anhydrous kerosene) was added, and the flotation time was 15 min, and the well completion fluid after solid phase separation was obtained by the treatment. The solid content of the well completion fluid obtained in Example 1 was analyzed, and the solid content was reduced to 0.98%.
[0056] Examples 2-12
[0057] The process operation procedures and methods of ultrasonic destabilization, flocculation + supergravity sedimentation and flotation treatment in Examples 2-12 of the application are the same as those in Example 1, and the difference lies in the changes of the ultrasonic power, ultrasonic time, addition amount of the composite flocculant, type and amount of the inhibitor, type and amount of the foam regulator and other process parameters, and the specific implementation conditions and impurity removal effects are shown in Table 6.
[0058] Table 6 Process parameters and test results in Examples 1-12
[0059]
[0060]
[0061] In the embodiment of the application, the destabilized well completion fluid enters the flocculation + supergravity sedimentation system to realize liquid-solid pre-separation; the liquid phase after the liquid-solid pre-separation enters the flotation system to further remove insoluble ultrafine particles, and the liquid phase after the liquid-solid pre-separation is shown in Figure 4 Figure 4 As shown in the left side of the figure, the impurities separated by the supergravity sedimentation mainly include shale impurities with large particles, Figure 4 The impurities removed by the middle right side flotation system are mainly superfine particles (≤8 μm) impurities.
[0062] Referring to the process parameters and test results in the above-mentioned Examples 1-12, when the process parameters are as follows: ultrasonic power 400-1200 W, ultrasonic time 4-8 min; the cationic polyacrylamide is added in a range of 0.2-0.8 mg / L, the polymeric ferric aluminum chloride is added in a range of 25-45 mg / L, the medicament action time is 2-5 min; the centrifugal force of the flocculation-ultra-gravity sedimentation system is in a range of 3500-4500 g; and the hydrophilic inhibitor is added in a range of 0.2-10 mg / L, and the foam regulator is added in a range of 0.1-1 mg / L, it is known that the liquid phase solid content in the above-mentioned Examples is all lower than 1%, thus meeting the requirements for recycling of the completion fluid. The above-mentioned method can realize efficient removal of insoluble inorganic / organic impurities in the completion fluid, effectively guarantee that the solid content of the completion fluid is lower than 1%, the liquid phase recycling rate is higher than 85%, the impurity removal process is refined, the application range is wide, the pollution to the environment caused by drilling waste is reduced, and resource waste is avoided.
[0063] In combination with the liquid phase solid content test results in the above-mentioned Examples 1-12, after the process parameters are gradually increased, the test results in Examples 2-4 are better than those in Example 1, similarly, the test results in Examples 6-8 are better than those in Example 5, and the test results in Examples 10-12 are better than those in Example 10; therefore, the ultrasonic power of the ultrasonic system is 600-1200 W, the ultrasonic time is 6-8 min; the cationic polyacrylamide is added in a range of 0.4-0.8 mg / L, the polymeric ferric aluminum chloride is added in a range of 30-45 mg / L, the medicament action time is 4-5 min; the centrifugal force of the flocculation-ultra-gravity sedimentation system is in a range of 4000-4500 g; the hydrophilic inhibitor is added in a range of 3-10 mg / L; and the foam regulator is added in a range of 0.3-1 mg / L.
[0064] More preferably, in combination with the test results in the above-mentioned Examples, after the process parameters are further increased, although the raw materials and resources (for example, the power is increased and the power consumption is increased) are increased, the liquid phase solid content is reduced instead of increased, therefore, Examples 2 and 3, and Examples 6, 7, 10 and 11 are more preferred, the ultrasonic power of the ultrasonic system is 600-800 W; the cationic polyacrylamide is added in a range of 0.4-0.6 mg / L, the polymeric ferric aluminum chloride is added in a range of 30-35 mg / L; the hydrophilic inhibitor is added in a range of 3-5 mg / L; and the foam regulator is added in a range of 0.3-0.6 mg / L.
[0065] The same, the present application to the proportion 1~the proportion 6 in the process operation process and method related to ultrasonic destabilization, flocculation+ultrahigh gravity sedimentation, flotation treatment in the example 1 are same, the difference lies in the change of ultrasonic power, ultrasonic time, composite flocculating agent dosage, inhibitor type and dosage, foam regulator type and dosage, etc.Process parameters, and the specific implementation conditions and impurity removal effect are shown in Table 7.
[0066] Table 7 Process parameters and test results in the proportion 1~the proportion 6
[0067]
[0068]
[0069] Proportion 1:
[0070] The specific implementation steps of the above proportion 1 are the same as the above example 1, and the main operation difference is that the ultrasonic power (350w) and ultrasonic time (3min) of the ultrasonic destabilization unit are lower, the composite flocculating agent is added to the destabilized completion fluid, the dosage of CPAM is 0.2mg / L, the dosage of PFAC is 25mg / L, the agent action time is 2min, and then the ultrahigh gravity sedimentation is carried out under the centrifugal force of 3500g; the liquid phase obtained by ultrahigh gravity sedimentation enters the flotation system, 0.2mg / L of salted water glass is added to the liquid phase, fully stirred for 3min, then 0.1mg / L of kerosene is added as a foam regulator, and the flotation time is 15min, the solid content of the treated completion fluid is 1.76%, which does not meet the reuse requirement because the solid content is greater than 1%.
[0071] Proportion 2:
[0072] The specific implementation steps are the same as example 1, and the main operation difference is that the flocculation+ultrahigh gravity sedimentation unit has lower flocculating agent dosage (0.15mg·L -1 CPAM+20mg·L -1 PFAC), agent action time (1min) and centrifugal strength (3000g). The solid content of the treated completion fluid is 2.36%, which does not meet the reuse requirement because the solid content is greater than 1%.
[0073] Proportion 3:
[0074] The specific implementation steps are the same as example 2, and the main operation difference is that the inhibitor dosage of the flotation unit is 0.1mg·L -1 . The solid content of the treated completion fluid is 1.98%, which does not meet the reuse requirement because the solid content is greater than 1%.
[0075] Proportion 4:
[0076] The specific implementation steps are the same as those of Example 2, and the main operation difference is that the amount of the foam regulator of the flotation unit is 0.05 mg·L -1 After treatment, the solid content of the obtained completion fluid is 2.05%, which is greater than 1% and does not meet the recycling requirements.
[0077] Comparative Example 5:
[0078] The specific implementation steps are the same as those of Example 5, and the main operation difference is that the amount of the foam regulator of the flotation unit is higher, i.e., 2 mg·L -1 After treatment, the solid content of the obtained completion fluid is 3.61%, which is greater than 1% and does not meet the recycling requirements.
[0079] Comparative Example 6:
[0080] The specific implementation steps are the same as those of Example 8, and the main operation difference is that the amount of the foam regulator of the flotation unit is higher, i.e., 1.5 mg·L -1 CPAM+60 mg·L -1 PFAC. After treatment, the solid content of the obtained completion fluid is 3.27%, which is greater than 1% and does not meet the recycling requirements.
[0081] With reference to the above Comparative Examples 1-6, with the process adjustment, although the solid content of the treated completion fluid is reduced, and the liquid phase recovery rate is also higher, it is obvious that the solid content of the treated completion fluid is still higher than 1% in the prior art “flocculation + centrifugation + membrane separation” technology, flocculation + pressure filtration” technology, and “natural sedimentation + static separation” technology, which cannot meet the recycling requirements.
[0082] Based on the same inventive concept, the embodiment of the present application also provides a solid phase separation system for a completion fluid, which can include an ultrasonic system, a flocculation-ultra-gravity sedimentation system, and a flotation system. The ultrasonic system is used to perform ultrasonic destabilization treatment on the completion fluid to be separated and treated at an ultrasonic power of 400-1200 W and an ultrasonic time of 4-8 min. The flocculation-ultra-gravity sedimentation system is used to perform liquid-solid pre-separation on stable flocculation after the action of a composite flocculant for 2-5 min. The flotation system is used to add a hydrophilic depressant to the pre-separated completion fluid for 3 min and then perform flotation operation for 15 min by adding a foam regulator.
[0083] Based on the same inventive concept, the embodiment of the present application also provides an application of the completion fluid separated and treated by the above-mentioned solid phase separation process for a completion fluid in a well completion engineering. The completion fluid separated and treated by the above-mentioned solid phase separation process for a completion fluid in the embodiment of the present application can realize efficient recycling of the completion fluid, thereby saving a large amount of resources and completion costs.
[0084] The system and the principle of solving the problem of the application embodiment are similar to the foregoing method, and therefore the implementation can be referred to the implementation of the foregoing method, and the repeated parts will not be described herein.
[0085] Obviously, various modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the claims and their equivalents, the application can be practiced otherwise than as specifically described.
Claims
1. A process for the separation of solids from a completion fluid, characterized in that, The application relates to a well completion fluid solid phase separation process method. The well completion fluid to be separated is placed in an ultrasonic system to perform ultrasonic destabilization treatment at an ultrasonic power of 400-1200 W and an ultrasonic time of 4-8 min; The well completion fluid after the ultrasonic destabilization treatment is transferred to a flocculation-ultra-gravity sedimentation system, and a composite flocculating agent is added to the flocculation-ultra-gravity sedimentation system to act on the stable flocculation for 2-5 min, and then liquid-solid pre-separation is performed on the stable flocculation; wherein the composite flocculating agent is a mixture of cationic polyacrylamide and polyaluminum ferric chloride. The well completion fluid after the pre-separation is placed in a flotation system, a hydrophilic depressant is added to the flotation system to act for 3 min, and then a foam regulator is added to the flotation system to perform flotation operation for 15 min.
2. The method of claim 1, wherein, The adding range of the cationic polyacrylamide is 0.2-0.8 mg / L, and the adding range of the polyaluminum ferric chloride is 25-45 mg / L. The centrifugal force range of the flocculation-ultra-gravity sedimentation system is 3500-4500 g.
3. The method of claim 2, wherein, The adding range of the cationic polyacrylamide is 0.4-0.8 mg / L, the adding range of the polyaluminum ferric chloride is 30-45 mg / L, and the medicament acting time is 4-5 min. The centrifugal force range of the flocculation-ultra-gravity sedimentation system is 4000-4500 g.
4. The method of claim 3, wherein, The adding range of the cationic polyacrylamide is 0.4-0.6 mg / L, and the adding range of the polyaluminum ferric chloride is 30-35 mg / L.
5. The method of claim 1, wherein, The hydrophilic depressant is salted water glass, acidified water glass or soluble starch; and the adding range of the hydrophilic depressant is 0.2-10 mg / L. The foam regulator is kerosene or silicon oil; and the adding range of the foam regulator is 0.1-1 mg / L.
6. The method of claim 5, wherein, The adding range of the hydrophilic depressant is 3-10 mg / L; and the adding range of the foam regulator is 0.3-1 mg / L.
7. The method of claim 6, wherein, The adding range of the hydrophilic depressant is 3-5 mg / L; and the adding range of the foam regulator is 0.3-0.6 mg / L.
8. The method according to any one of claims 1 to 7, characterized in that, The ultrasonic power of the ultrasonic system is 600-1200 W, and the ultrasonic time is 6-8 min.
9. The method of claim 8, wherein, The ultrasonic power of the ultrasonic system is 600-800 W.
10. A solids separation system in a completion fluid, characterized by, The application relates to a well completion fluid solid phase separation process method. The ultrasonic system is used for performing ultrasonic destabilization treatment on the well completion fluid to be separated at an ultrasonic power of 400-1200 W and an ultrasonic time of 4-8 min; the flocculation-ultra-gravity sedimentation system is used for performing liquid-solid pre-separation on the stable flocculation after the composite flocculating agent acts for 2-5 min; and the flotation system is used for adding the hydrophilic depressant to the pre-separated well completion fluid to act for 3 min, and then adding the foam regulator to perform flotation operation for 15 min.
11. Application of the well completion fluid separated by the well completion fluid solid phase separation process method according to any one of claims 1-9 to well completion engineering.